GB2392421A

GB2392421A - Suspension system

Info

Publication number: GB2392421A
Application number: GB0300653A
Authority: GB
Inventors: Andrew Harrison; Paul Saulitis; David Bloxham
Original assignee: Trelleborg AB
Current assignee: Trelleborg AB
Priority date: 2003-01-13
Filing date: 2003-01-13
Publication date: 2004-03-03
Also published as: GB2392421A9; GB0300653D0

Abstract

An integrated valve controller for an electronically controlled air suspension (ECAS) system comprises a plurality of electromechanically operable pneumatic valves 50 for controlling air flow within the ECAS. An electronic control unit (ECU) 42 controls the pneumatic valves. The ECU and the pneumatic valves are contained within a unitary housing 56.

Description

SUSPENSION SYSTEM

The present invention relates to vehicle suspension systems.

Important aspects of automotive vehicle handling are vehicle stability, and ensuring the vehicle remains in good contact with the road. It is also desirable for the ride to be smooth. The vehicle's suspension system is a key element for determining these aspects.

Conventional automotive vehicle suspension systems comprise springs which are forced into compression when the vehicle encounters rises in the surface of the road, and dampers to control the recoil of the spring, thereby damping out oscillations. These systems suffer several disadvantages including wear of the springs with time, reduced ability to remain stable and level because of uneven distribution of loads and the inability to react to changes in load mass or distribution.

Suspension systems are also known which use air flow to an air suspension unit (air spring) instead of the spring and damper system described above. Typically these systems are controlled electronically so that the flow of air to each air spring can be adapted according to the road surface and load conditions at any particular time. The supply of air to and from the suspension system is controlled with electromechanically operated pneumatic valves. A problem with these systems is that substantial lengths of piping and wiring are required for the air, power and control lines to each of the pneumatic valves. These systems require a wiring harness, and are labour intensive to install.

It is an aim of the present invention to provide an improved vehicle air suspension system of a compact design, which alleviates the aforementioned problems. According to the present invention there is provided an electronically controlled air suspension (ECAS) system comprising: a plurality of electromechanically operable pneumatic valves for controlling air flow within the ECAS; an electronic conko1 unit (ECU) for controlling the pneumatic valves; and characterised by a unitary housing containing the electronic control unit and the pneumatic valves.

Preferably the electronic control unit and pneumatic valves are provided with power by a single power line. The pneumatic valves may be solenoid valves of a compact type.

It is an advantage, in embodiments of the invention, that the integrated assembly allows a reduction in the number and length of electrical wiring connections serving the ECU and valves. Only a single power cable providing power to the integrated unit is required. In prior art air suspension

systems each valve is mounted separately from the ECU, which means that separate wiring connections are required for providing power to the ECU and each pneumatic valve. Thus prior art systems require a wiring harness,

which is eliminated in the system of the present invention.

It is a further advantage that the integrated assembly is more compact than known air suspension systems where the ECU is separate from the valves. This provides both space and weight savings.when compared with

known systems, because of reductions in the amount of wiring, the length of pneumatic piping and the number of mounting brackets required. Assembly of the system into the vehicle is also greatly simplified. These advantages in turn reduce the production cost of the system.

In a preferred embodiment the unitary housing comprises a manifold.

The manifold may include apertures for connection to respective pneumatic pipes, each aperture forming a flow passage for air between the pneumatic pipe and a port of a respective pneumatic valve. Each aperture may include a push-fit connector for connection of the respective pneumatic pipe.

It is an advantage that the use of push-fit connectors facilitates rapid assembly as well as ease of disconnection and reconnection of the system for maintenance. Preferably, the electronic control unit and the pneumatic valves are secured with a rubber-like 'potting' compound. This is advantageous because as well as holding the components firmly together it provides environmental protection. An embodiment of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic view of a vehicle having a known air suspension system; Figure 2 is a schematic view of a vehicle having an air suspension system according to the present invention;

Figure 3 is an exploded view of an integrated assembly forming part of the suspension system according to the present invention; and Figure 4 is a three dimensional view of the integrated assembly of figure 3.

Figure 1 shows a known air suspension system for a vehicle 1O, having a body 12 and wheels 14. The vehicle body 12 is supported above the wheels on air suspension units 11. Air from a compressed air supply 16 is supplied to the suspension units 11 via pneumatic valves 18 through pneumatic lines 20. The pneumatic valves 18 control the flow of compressed air tO, and exhaust air from the suspension units 11, thereby controlling the air pressure within each of the suspension units 11. The pneumatic valves 18 are actuated by solenoids (not shown), electronically controlled by an electronic control unit (ECU) 22. Sensors (not shown) provide signals to the ECU for controlling the system. Sensors may include vehicle body height sensors, air pressure sensors, and airflow sensors. A battery 24 provides power via power line 25 to the ECU 22 and via power lines 26 to each of the valves 18. The valves 18 are controlled by control signals from the ECU 22 provided on control signal lines 28.

In use, when the vehicle 10 encounters an uneven road surface, the suspension system reacts by controlling the air pressure in the suspension units 11 to control the vehicle's ride and stability in response to sensor signals. The air pressure is controlled by opening and closing of the pneumatic valves 18 under the control of the ECU 22.

Referring to Figure 2, an air suspension system for a vehicle 30 has air suspension units 32 supporting the vehicle body 33 above the wheels 34.

Air is supplied from a compressed air supply 36 to a valve controller 38.

The valve controller 38 includes an ECU 42 and a block of pneumatic valves 50 as will be described below with reference to Figure 4. The pneumatic valves 50 are operated by solenoids (not shown) controlled by control signals from the ECU 42. The pneumatic valves 50 control the flow of air through pneumatic lines 40 to the suspension units 30. A battery 44 provides power via a single power line 46 to both the ECU 42 and the solenoids in the valve controller 38.

Figure 3 shows the constituent parts of the valve controller 38 of Figure 2. An ECU 42 is in the form of a printed circuit board (PCB) 43.

Solenoid wire coils 52, (of which five are shown in figure 3) are mounted to the lower surface 43 of the PCB, and each coil 52 has a respective plunger 54 which is moveable therein. Current supplied to a solenoid coil 52 produces a magnetic field, which causes movement of the respective plunger 54.

The plungers 54 are each connected to a respective valve member in a pneumatic valve 50. The ECU 42 controls opening and closing of the pneumatic valves by controlling when current is provided to each of the solenoid coils 52 so as to move the plungers 54.

The valve controller 38 includes an injection moulded plastics manifold 56. The manifold 56 forms a unitary housing for the controller components. A rubber-like 'potting' compound is used to secure the components into place. Pneumatic lines (not shown) can be connected to the manifold 56 via push fittings 58, through apertures 60 in the base of the manifold 58. Power to both the ECU 42 and the solenoid coils 52 is provided from a battery (not shown) through a cable to a connector terminal 48.

Figure 4 shows the valve controller 38 in its assembled form. Typical dimensions of the valve controller 38 are length L= 113 mm, width W=73 mm and height H=83 mm. This represents a very compact unit, which can easily be assembled in a vehicle and allows ease of access for maintenance.

Compared with an equivalent known system where the ECU and valves are mounted separately and remotely from one another, this embodiment provides a space saving of approximately 80%, a weight saving of approximately 82 %, and a reduction in copper usage of approximately 75 %.

In use, the system described above controls the vehicle ride and stability by adjusting the air pressure and volume in each of the air suspension units 11. This is done in response to signals from sensors which are provided to the ECU 22. The system can be configured with a variety of features including: Load levelling' in which the vehicle body is maintained at a predetermined height regardless of payload; Extended ride height' in which the vehicle body can be raised by a predetermined amount for driving over rough or uneven terrain (for example off-road); High speed lowering' in which the vehicle body is automatically lowered by a predetermined amount when the vehicle reaches a predetermined speed. This improves stability at high speeds. When the speed falls, the vehicle body is automatically raised back to the original or normal' height.

Claims

1. An electronically controlled air suspension (ECAS) system comprising: a plurality of electromechanically operable pneumatic valves for controlling air flow within the ECAS; an electronic control unit (ECU) for controlling the pneumatic valves; and characterised by a unitary housing containing the electronic control unit and the pneumatic valves.

2. An air suspension system as claimed in claim 1, wherein the unitary housing comprises a manifold including apertures for connection to respective pneumatic pipes, each aperture forming a flow passage for air between the pneumatic pipe and a port of a respective pneumatic valve.

3. An air suspension system as claimed in claim 2, wherein at least one aperture includes a pushiest connector for connection of the respective pneumatic pipe.

4. An air suspension system as claimed in any preceding claim, wherein the electronic control unit and pneumatic valves are provided with power by a single power cable.

5. An air suspension system as claimed in any preceding claim, wherein the electromechanical valves are solenoid valves of a compact type.

6. An air suspension system as claimed in any preceding claim, wherein the electronic control unit and the pneumatic valves are secured with a rubber-like 'potting' compound.

7. A valve controller for an electronically controlled air suspension system (ECAS), the integrated valve controller comprising: a plurality of electromechanically operable pneumatic valves for controlling air flow within the ECAS; an electronic control unit (ECU) for controlling the pneumatic valves; and characterised by a unitary housing containing the electronic control unit and the pneumatic valves.

8. A valve controller as claimed in claim 7, wherein the unitary housing includes apertures for connection to respective pneumatic pipes, each aperture forming a flow passage for air between the pneumatic pipe and a port of a respective pneumatic valve.

9. A valve controller as claimed in claim 8, wherein at least one aperture includes a push-fit connector for connection of the respective pneumatic pipe.

10. A valve controller as claimed in any one of claims 7 to 9, including a connection terminal for connection to a single power cable for providing power to the ECU and pneumatic valves.

11. A valve controller as claimed in any one of claims 7 to 10, wherein the electromechanical valves are solenoid valves of a compact type.

12. A valve controller as claimed in any one of claims 8 to 12, wherein components of the integrated controller are secured with a rubber-like potting' compound.