IMPACT 4.02.11
31/01/17
5618/Description, Design and function//APM, component description
FH (4)
137108017
21/05/16
APM, component description description APM Overview PBRAKE-E (parking brake electrical) PBRAKE-P (parking brake pneumatic) Description The air drier phases Charging phase Relief phase Regeneration phase Functions Related information
APM (Air Production Modulator) Modulator) Overview
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
1 / 23
IMPACT 4.02.11
31/01/17
Note There are two versions of the APM.
PBRAKE-E (parking brake electrical)
Air connections connections
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
2 / 23
IMPACT 4.02.11
31/01/17
APM symbols description Symbol
Description
C1, C2, ......, C6
Circuit 1, Circuit 2, ......., Circuit 6
CP
Central plug
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
3 / 23
IMPACT 4.02.11
31/01/17
CTR
Desiccant cartridge
CV1, CV2
Check valve 1, Check valve 2
CVS
Check valves serial
EAC
Electronic air control
ECU
Electronic control unit
EX, ESS
Exhaust, Energy saving system
HT
Heating element
MV
Magnetic valve (solenoid)
PB
Parking brake
PBRV
Parking brake relay valve
PCD
Pressure compensation device
PCV
Pneumatic control valve
PL
Pressure limiter
PR
Pressure regulator
PS
Pressure sensor
PV
Protection valve (circuit)
REG
Regeneration
SHV, SLV
Select high valve, Select low valve
SC
Spring chambers
SV
Safety valve
TH
Throttle
PBRAKE-P (parking brake pneumatic)
Air connections Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
4 / 23
IMPACT 4.02.11
31/01/17
APM symbols description Symbol
Description
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
5 / 23
IMPACT 4.02.11
31/01/17
C1, C2, ......, C6
Circuit 1, Circuit 2, ......., Circuit 6
CP
Central plug
CTR
Desiccant cartridge
CV1, CV2
Check valve 1, Check valve 2
CVS
Check valves serial
EAC
Electronic air control
ECU
Electronic control unit
EX, ESS
Exhaust, Energy saving system
HT
Heating element
MV
Magnetic valve (solenoid)
PB
Parking brake
PBRV
Parking brake relay valve
PCD
Pressure compensation device
PCV
Pneumatic control valve
PL
Pressure limiter
PR
Pressure regulator
PS
Pressure sensor
PV
Protection valve (circuit)
REG
Regeneration
SHV, SLV
Select high valve, Select low valve
SC
Spring chambers
SV
Safety valve
TH
Throttle
Description Variants Pneumatic distribution center location Variant symbol
Variant description
PDC-IF
Pneumatic distribution centre location, inside frame.
PDC-IFR
Pneumatic distribution centre location, inside frame, rear.
PDC-OFF
Pneumatic distribution centre location, outside frame, front.
PDC-OFM
Pneumatic distribution centre location, outside frame, middle. Pneumatic distribution centre location, outside
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
6 / 23
IMPACT 4.02.11
31/01/17
PDC-OFR
frame, rear.
Brake system variants Variant symbol
Variant description
BSYS-CON
Brake system, conventional
BSYS-EBS
Brake system, electronic
Parking brake system variants Variant symbol
Variant description
PBRAKE-E
Electric parking brake
PBRAKE-P
Pneumatic parking brake
Clutchable air compressor Variant symbol
Variant description
CLU-AIRC
Clutchable air compressor (Enables the compressor to operate only when needed, which reduces the fuel consumption).
UCLUAIRC
Without clutchable air compressor.
The incoming air from the compressor can contain some water, oil and pollutants. When compressed air expands and cools down, the water in it condenses. The vehicle's pneumatic system must be protected against internal corrosion and its piping against freezing, so the air must first be filtered and dried. This is done using an air drier that removes excess water and oil residue. APM The purpose of the APM is to: ●
Manage production of compressed air
●
Ensure that the air is dry
●
Distribute the dried air to all the pneumatic systems in the vehicle
●
Protect circuits against leakage (by using the safety valves)
●
Apply the parking brake.
The APM is a compact component, containing: ●
Air drier components (including desiccant cartridge)
●
Control unit, connected to the chassis subnet data link and to parking brake handle with LIN (Local Interconnect Network) 12
●
4-circuit valve
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
7 / 23
IMPACT 4.02.11
●
Two protection valves
●
Parking brake relay valve with exhaust silencer
●
Pressure limiter
●
Solenoid actuator
●
Compressor regulator
●
Pressure sensors
●
Heater resistor.
31/01/17
By allowing the control unit to manage the regeneration phase, air drying can be optimised, which leads to a longer life for the desiccant cartridge (a molecular filter, which collects the water under high pressure). This closed system cannot be overhauled, but since the number of valves, pneumatic and electrical connectors is reduced, the risk of leakage and electrical failure is minimised and results in a more stable and reliable system. The APM is completely integrated into the vehicle data link system and can thereby communicate with other control units in the electrical system. Air drier In the air drier the air first passes through an oil filter which collects water droplets, oil and pollution particles; that are drained through the exhaust valve at the bottom of the air drier during the regeneration phase. The air then flows through the desiccant cartridge, where any remaining water is separated by means of absorption, which means that a very porous granulated desiccant (molecular filter) collects the water under high pressure. The dry air is then distributed to the vehicle’s air system. Note The presence of water in the housing below the filter cartridge is completely normal. All the water from the compressed air collects at the bottom of the housing and is blown out through the outlet port.
Desiccant cartridge The desiccant cartridge contains a porous granulate which absorbs and retains water, and an oil filter that takes care of the oil residue from the compressor. To prevent the desiccant cartridge from becoming saturated, regeneration takes place during the relief phase, which means that air from the compressed air tanks flows in the opposite direction through the air drier and expands to atmospheric pressure. The reduction in pressure releases water from the desiccant, which is picked up by the air, carried out of the desiccant cartridge and drained. This process is also called desorption. Additionally, a pop-up message and a yellow warning lamp alert the driver to stop due to possible damage in the braking circuit when the desiccant cartridge needs replacing. Note The desiccant cartridge must be replaced according to the service program.
The four-circuit valve The four-circuit valve is completely integrated into the closed system and distributes the compressed air to the various pneumatic systems in the vehicle. The distribution is controlled by an order of Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
8 / 23
IMPACT 4.02.11
31/01/17
priority which ensures that the compressed air is distributed in such a way that the vehicle always has braking power. The service brake system has the highest priority, and the parking brake system the lowest priority. Additionally, compressed air is used by ●
the air pump used for injecting diesel exhaust fluid (AdBlue) into the exhausts to reduce emissions (Euro6 vehicles).
●
the AFI (Aftertreatment Fuel Injector) for injecting fuel into the exhaust for regeneration of the diesel particular filter.
●
the air suspension.
●
the gear change system.
Control unit The APM is completely integrated into the vehicle data link system and can thereby share information with other control units in the electrical system. ●
This integration means that the APM can control air drying and optimise its production. Also, the production and distribution of compressed air can be optimised in accordance with the vehicle's conditions.
●
Connection via the data link also makes it possible to check the air pressure and send fault codes to the driver. The APM can then use the codes to report everything from possible leakage to reduced braking power or a saturated desiccant cartridge.
●
The control unit manages the different phases of the air drier and can thereby optimise the desiccant cartridge life by only regenerating when necessary.
●
The control unit contains sensitive pressure sensors, which makes it extremely sensitive to external forces and makes it impossible to overhaul.
●
The control unit also regulates the heating of the air drier, which prevents fluid from freezing inside the unit.
Different levels of pressure In order to better utilise surplus energy and further optimise the build-up of pressure, the cut-in and relief pressures are set to suit the current conditions. The APM works in the following modes.
Levels
Vehicle speed
Compressed air consumption
Cut-in pressure
Relief pressure
Low speed mode
<35 km/h
High
1,100 kPa
1,250 kPa
High speed mode
>35 km/h
Low
1,100 kPa
1,200 kPa
N/A
1,200 kPa
1,250 kPa
Engine braking mode The vehicle is being braked by the engine, the energy required to drive the N/A compressor is free and the control unit allows the pressure to build up to a maximum.
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
9 / 23
IMPACT 4.02.11
31/01/17
Integrated heater Around the pressure relief valve, there is a thermostatic controlled heating element which prevents ice formation in cold weather. In cold conditions and vehicle mode set to pre-running or running, APM automatically switches on the integrated heater to warm up the relief valve. Air connections The air connections are mainly grouped on one side of the APM. The hoses are connected to APM using nipples with a simple locking mechanism, which allows easy installation. The nipples are easily disconnected using a special tool. The connection for incoming air from the compressor on port 11 is the only screw fitting. The exhaust ports are located under the APM. There are silencers on the exhaust ports, which ensure that the noise level is kept low during regeneration and unloading. Heating loops and regular exhausting prevent ice from building up at the exhaust ports. Note Different types of air drier exist, depending on the supplier. Early models have a swivel at port 6 (parking brake cylinder, pressure information). The test nipple at port 29.2 is optional and only valid for PBRAKE-E (electric parking brake). Port 28 supplies the hand control for PBRAKE-P (pneumatic parking brake).
Air connections
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
10 / 23
IMPACT 4.02.11
31/01/17
Electrical connection
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
11 / 23
IMPACT 4.02.11
31/01/17
The electrical connection is located on the opposite side of the APM.
The air drier phases The air drier operates with different phases to build up, retain, regenerate and rebuild pressure. The various phases are controlled by the APM in accordance with the requirements of the vehicle, which reduces the number of components and minimises wear.
Charging phase
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
12 / 23
IMPACT 4.02.11
31/01/17
A. Moist air from the compressor B. Dried air 1
The compressor’s relief valve is closed when a request for pressure is received from the control unit.
2
Untreated air from the compressor flows in through port 11 to the desiccant cartridge’s preliminary chamber, which is equipped with a filter that separates the oil residue from the compressed air.
3
The air is carried through the sides of the cartridge up to its top, and then down through a primary filter and through the desiccant. The desiccant absorbs and collects the water from the compressed air so that the air is dried.
4
Once the air has been dried, it arrives at a safety valve housing, which uses overflow valves to
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
13 / 23
IMPACT 4.02.11
31/01/17
control pressure prioritisation and maintains the independence of each compressed air circuit. Pressure to one of the service brake circuits is prioritised and when there is sufficient pressure, valves open to increase the pressure in the other circuits. Pressure limiting valves limit the maximum pressures in the trailer and parking brake circuits. 5
The pressures in the front and rear brake supply circuits are measured by pressure sensors PS C1 and PS C2 respectively.
Relief phase When the pressure in the front brake circuit has reached its regulation level, the control unit begins the relief phase by opening the relief solenoid valve (MV1), which pneumatically then opens the relief valve. A non-return valve maintains the pressure in the system. UCLUAIRC: Port 27 sends a pressure signal which activates the compressor unloading. Incoming air from the compressor (port 11) is now taken directly to the exhaust port (31). CLU-AIRC: Port 27 sends a pressure signal to the clutch, which disengages the compressor and stops the air flow.
Regeneration phase
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
14 / 23
IMPACT 4.02.11
31/01/17
A. Moist air from the desiccant cartridge B. Dried air from the air tanks The regeneration phase is started automatically each time the compressor unloads, but the length of the regeneration phase varies according to the amount of air that has passed through the desiccant cartridge since the previous regeneration. 1
The amount of air is calculated by the APM on the basis of information from the pressure sensors and the ECM (Engine Control Module), which reports the engine speed. The APM converts the engine speed to delivered air flow on the basis the compressor characteristics.
2
The solenoid valve which controls regeneration (MV2) is managed by the APM.
3
The non-return valve, which normally prevents air from the air tanks from flowing in the wrong direction, is bypassed by the open regeneration solenoid valve, which directs dry air from the tanks (ports 21 and 22) to flow in the other direction through the desiccant cartridge and out
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
15 / 23
IMPACT 4.02.11
31/01/17
through port 31. 4
A non-return valve prevents the escaping compressed air from flowing back into the air tanks.
5
The atmospheric pressure releases the water from the desiccant cartridge, which means that water, dirt and oil follow the compressed air out through port 31.
6
A silencer dampens the noise level from the exhaust port.
The system also performs a brief regeneration when the vehicle stops, so that no pressurised air remains in the system while the vehicle is not in use. It is perfectly normal for oil residue to be present at the exhaust port opening, and no action needs to be taken.
Functions The APM controls many functions, such as: ●
Compressor control (cut-in/cut-off, controlled pressure levels for circuits)
●
Air pressure distribution to all pneumatic circuits on the vehicle
●
Leakage protection
●
Air treatment (retains water, dust/particles and oil leaving compressor)
●
Driver information (air gauges, parking brake indicator (P), parking brake alerts, air management, desiccant cartridge maintenance)
●
Miscellaneous info
●
Parking brake management
Air distribution and circuit protection The air distribution and circuit protection function enables the distribution of dried, purified and pressure controlled air to each consuming circuit. Each circuit is protected against leakage and if a leaking circuit is detected, it is isolated from the other circuits. The pressure in the remaining circuits is always kept at a level that meets the legal requirements. Air leakage detection The APM monitors the activity of the air consuming units during vehicle operation. No air consumption is indicated via the CAN (Controller Area Network) bus, the APM monitors pressure variations in the air tanks and can detect air leakage. ●
When leakage reaches the first level, no message is shown in the Instrument, but a fault code is set internally in the APM and can be read with the diagnostic tool (Volvo Tech Tool).
●
When leakage reaches the second level, a fault code is set in the APM and a pop-up message is shown in the instrument.
Note After a repair, "reset of air leakage value" must be executed to erase the fault code.
Air treatment
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
16 / 23
IMPACT 4.02.11
31/01/17
During the charging phase (compressor cut-in), dust, water and oil rejects are retained by the cartridge. Each time the compressor is relieved, APM port 27 is pressurised, which means that the compressor is set to atmospheric pressure, a pneumatic exhaust noise occurs and, for CLU-AIRC, the compressor is disengaged, and a regeneration phase is set: clean air taken from air tanks is reverse injected in the cartridge to clean it. The amount of clean air taken back is proportional to the previous cut-in phase duration, which means that if previous cut-in phase has been long or very long, several successive regeneration phases can occur. At engine shut-down, an exhaust of the compressor pipe and the desiccant cartridge is done. Moreover, a final regeneration could be launched if it is set by parameters. Note In extreme conditions (high air demands), a long charging phase can lead to temporary cartridge desiccant saturation and the risk of water entering the air tanks. The cartridge desiccant will be recovered by successive regeneration phases, but the water will remain in the tanks. This water must be drained from the tank. APM takes into account this long charging phase and the quantity of water in the air tanks is shown in diagnostic tool (Volvo Tech Tool) through a level indicator. If the level is below 5, the risk is low. If it is above 5, the risk is significant and proportionate to the level. The air tank check interval must be adapted to suit the risk level.
Air quantity Based on four pressure sensors, the APM controls the air pressures in the front brake circuit (one sensor), the rear brake circuit (one sensor) and the parking brake circuit (two sensors). It also detects if the parking brake is applied. This information is used in three ways: ●
The instrument panel displays the pressure in the front and rear brake circuits.
●
A warning lamp indicates when the air pressure is too low.
●
The parking brake indicator (P) lights when the parking brake is applied.
Anti-compound Anti-compound prevents the simultaneous application of the service and the spring brakes. In order to limit efforts on the brakes, the APM limits the parking brake force on the spring brake cylinders as soon as the service brakes are applied, by using the pneumatic connection between the service brakes on the rear axle and the APM port 4.2. When the service brakes are applied, the pressure consequently increases in port 4.2 and compressed air is re-injected into the spring brake cylinders to partially release the parking brake. This function is 100% pneumatically activated. BSYS-EBS Additionally, EBS (Electronically controlled Brake System) limits the pressure in the wheel brakes when parking brake is applied. Cartridge predictive maintenance Depending on air consumption, the APM calculates the percentage wear on the desiccant cartridge since it was installed in the system. This percentage is weighted to check whether the high air consumption is a temporary condition or not. The maintenance function is managed by the APM. When the cartridge is exchanged, the counters (date and wearing %) must be reset, either via a menu in the instrument or with the diagnostic tool (Volvo Tech Tool). When the reset is performed, a signal is sent to the VMCU (Vehicle Master Control Unit), which resets the data in the APM. If the cartridge is not exchanged when requested, a yellow warning lamp alerts the driver to go to a workshop immediately due to possible damage in the air system circuit. Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
17 / 23
IMPACT 4.02.11
31/01/17
●
When the wear level reaches 92%, a fault code is set internally in the APM and can be read with the diagnostic tool (Volvo Tech Tool).
●
When the wear level reaches 100%, an alert pop-up regarding required service is shown in the instrument.
●
If the desiccant cartridge is not replaced, and reset not performed, when 150% wear is indicated, a fault code is set and an alert pop-up regarding air system failure is shown in the Instrument together with a SERVICE symbol.
Note The calculation of desiccant cartridge usage is performed in the APM. The calculated percentage usage is stored both in APM and in VMCU. When the cartridge is exchanged, the counters (date and % wearing) must be reset in both APM and in APM, either via a menu in the Instrument or with the diagnostic tool (Volvo Tech Tool). If the cartridge is replaced, but without resetting the counters, the SERVICE symbol remains active. When the reset is performed, a signal is sent to the VMCU, which resets the data in the APM.
Precondition: ●
Vehicle mode pre-running or running.
Compressor control All the compressed air used in the vehicle (for braking, suspension and auxiliaries) is produced by a compressor linked to the engine, and stored in air tanks. The compressor control function regulates the pneumatic pressure levels in the consuming circuits, by controlling the compressor’s charge/relief phases. This function operates in different modes depending on the current pressure level and vehicle status. The modes are prioritised the following way: 1
Overtake
2
Overrun
3
Low/High speed
Overtake mode When a demand for maximum engine power is detected by the engine (for example for overtaking) the ECM sends a signal to the APM to disengage the compressor in order to avoid unnecessary load. Preconditions: ●
Vehicle mode running.
●
Vehicle speed as specified below.
●
The air pressure in the braking system as specified below.
Tech data Vehicle speed
>35 km/h
Air pressure
>1,150 kPa
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
18 / 23
IMPACT 4.02.11
31/01/17
Overrun mode To take advantage of the engine brake force energy during an engine brake phase (no fuel injection), the APM engages the compressor in order to build up the pressure in the air tanks without any extra fuel consumption. Preconditions: ●
Vehicle mode running.
●
Vehicle speed as specified below.
●
The air pressure in the braking system as specified below.
Tech data Vehicle speed
>35 km/h
Air pressure
<1,200 kPa
Low speed mode As long as the vehicle speed is below a predefined value, the pressure in the air tanks is kept as high as possible to reduce pneumatic response times, in case of, for example, a possible demand from the air suspension system. The APM controls the dynamic cut-in/cut-off thresholds (parameters) of the compressor according to low speed mode. Preconditions: ●
Vehicle mode running
●
Vehicle speed as specified below.
Tech data Vehicle speed
<35 km/h
High speed mode As long as the vehicle speed is above a defined value, it is not necessary to have the highest air pressure as possible in the air tanks. To limit fuel consumption, the APM controls the dynamic cut-in/cut-off thresholds (parameters) of the compressor corresponding to high speed mode. Preconditions ●
Vehicle mode running
●
Vehicle speed as specified below.
Tech data Vehicle speed
>35 km/h
Driver information The APM transmits information to the driver regarding: ●
Front and rear brake circuits pressure levels
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
19 / 23
IMPACT 4.02.11
●
Parking brake status
●
Over usage of the compressor
●
Air system leakage
●
Upcoming desiccant cartridge change
●
Low air pressure alert
●
System failure indication
31/01/17
The APM monitors the pressure in the air circuits and activates pop-up messages in the Instrument: ●
Pressure is inadequate: A pop-up message alerts the driver to check the pressure.
●
Pressure is low: The STOP symbol is displayed along with a pop-up message alerting the driver to check the pressure.
Engine start help If there is sufficient pressure, the APM disengages the compressor during cranking. Preconditions: ●
Vehicle mode cranking
●
Pressure is above threshold
Engine speed control Empty air system at engine start: When the air tanks are empty, and depending on external status (e.g. vehicle standing still, no gear engaged, no active PTO (Power Take-Off)), the APM increases engine speed for quicker air filling. Pressure drop while the engine is running (high air consumption): When the air pressure in the air tanks falls below the nominal working range (between compressor cut-in and cut-off) down to predefined values, and if conditions and vehicle status allow it, the APM increases engine speed to increase or minimise the decrease of the pressure in the air tanks. Engine speed control adjusts the engine speed depending on the pressure level in the system and is activated when: ●
the air system is empty on engine start, or
●
the pressure drops while the engine is running (high air consumption).
Preconditions ●
Vehicle mode running
●
Engine running
●
Gearbox in neutral
●
Vehicle standing still
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
20 / 23
IMPACT 4.02.11
31/01/17
●
Compressor status = charging
●
Enabled by parameter setting (disabled by default).
Empty air system: When the air tanks are empty, and depending on external status (e.g. vehicle is stationary, no gear engaged, no active PTO), the APM increases engine speed for quicker air filling. Engine start: At engine start, if the air pressure in the air tanks is lower than a pre-defined value and if conditions and vehicle status allow it, the APM increases engine speed to quickly increase the pressure in the air tanks. Pressure drop while the engine is running (high air consumption): When the air pressure in the air tanks drops below the nominal working range (between compressor cut-in and cut-off) down to predefined values, and if conditions and vehicle status allow it, the APM increases engine speed to increase or minimise the decrease of the pressure in the air tanks. Fan activation request The temperature of the air from the compressor to the APM must be limited to achieve optimal desiccant cartridge drying performance and optimal service life of the integrated components. When the air delivered by the compressor under certain conditions (vehicle speed, ambient temperature) is at a high temperature level, the APM requests the cooling fan to start. The compressor discharge line is designed to allow the cooling air flow generated by the engine cooling fan to pass through. This function is mainly used at vehicle standstill with engine running or at very low speed (typically in construction applications). Preconditions: ●
Vehicle mode running
Parking brake The parking brake function comprises the following features: ●
Manual activation by using the parking brake handle.
●
Automatic activation at vehicle stand still and key off or remote key off or idle shut down.
●
Manual release by using the parking brake handle is designed to prevent unintentional release of the parking brake.
●
Automatic release (only AMT (Automated synchronized Mechanical Transmission) (or where available APS (Automated Power Shifting)) with EBS) when the vehicle takes off.
●
Proportional braking as back-up, in the event of a problem with the service brake system, activates both the spring brakes on the vehicle and the service brakes on the trailer.
The APM communicates with the parking brake handle. The handle communicates with the APM via LIN 12. There is a red LED in the parking brake handle, indicating when the parking brake is applied. Note The trailer service brakes are not activated.
Limp-home If a fault should arise either in the electronic or in the electro-pneumatic system, the relief solenoid valve (MV1) and the regeneration valve (MV2) are switched off. However, to protect the various air Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
21 / 23
IMPACT 4.02.11
31/01/17
circuits, pressure regulation is still possible. In limp-home mode, the system works in the following sequence: 1
Increasing air pressure in the circuits as long as the pressure is insufficient and the relief valve remains closed.
2
When the pressure increases, air from the compressor starts to open the relief valve.
3
As the pressure increases further, the pneumatically controlled relief valve opens further.
4
At the point when the pressure reaches limp home pressure, the relief valve is completely open. Incoming air from the compressor is now led directly to the exhaust port. The non-return valve prevents the pressure in the circuits from dropping.
Tech data Limp home pressure
1,150 kPa
Note In the limp-home mode there is no regeneration and the compressor relief is not controlled. As a result the STOP lamp lights on the instrument panel.
System pressure limitation (BSYS-EBS) If the EBS system enters back-up mode (for example loses the electronic service brake pressure control possibility) or there is no CAN communication between the EBS and the APM, the EBS cannot limit the air pressure. At this moment, the APM system takes over the responsibility to limit the brake system pressure to avoid wheel brakes overload in the event of full brake pedal application. When the EBS system is in back-up mode, the APM limits the air tank pressure level. Notable behaviour In Euro6-classified vehicles, the compressor is engaged more frequently due to constant air consumption.
Related information For more information on the electrical architecture, refer to: Wiring diagram ➠ Vehicle electronics overview, system description Related functions ➠ Parking brake, function description ➠ Service braking, function description Related systems ➠ Air supply, system description ➠ Service braking, system description ➠ Trailer brake, system description ➠ Wheel brake, system description Related components ➠ Air valve, component description ➠ Compressor ➠ Footbrake valve, component description
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
22 / 23
IMPACT 4.02.11
➠ ➠ ➠ ➠ ➠ ➠ ➠ ➠
31/01/17
Parking brake control (HCU), component description Modulators, component description Relay valve, component description Solenoid valve, 1-channel, component description Solenoid valve, 2-channel, component description Solenoid valve, 4-channel, component description Trailer brake control valve, component description Brake cylinder, component description
Copyright to this documentation belongs to the Volvo Group. No reproduction, copying, change, amendment or other similar disposal is entitled without prior written consent by the Volvo Group The information contained herein is current at the time of its original distribution, but is subject to change. The reader is advised that printed copies are uncontrolled.
23 / 23
