BMW 7 Series: ARS Hydraulic Valve Manifold

Fig. 121: Identifying ARS Hydraulic Valve Manifold Components

INDEX REFERENCE CHART

1. Front-axle pressure valve [PVV]
2. Rear-axle pressure valve [PVH]
3. Switch-position detector [SSE]
4. Front-axle pressure sensor [DSV]
5. Rear-axle pressure sensor [DSH]
6. Failsafe valve [FS]
7. Direction valve [RV]

The hydraulic valve block is located on the floor plate of the vehicle behind the front right-hand wheel housing level with the front right-hand door. The hydraulic valve block is connected to a carrier plate bolted to the body.

The hydraulic valve block houses the following valves and sensors:

• 2 pressure valves; 1 for the front suspension and 1 for the rear suspension [these are proportional pressure limiting valves]
• 1 directional control valve
• 1 failsafe valve
• 2 pressure sensors; 1 sensor for the front suspension, 1 sensor for the rear suspension
• Switch-position detector

Tandem Pump

Fig. 122: Identifying Tandem Pump Components

INDEX REFERENCE CHART

1. Radial piston pump (ARS)
2. Intake restrictor valve
3. Electronic volumetric flow control (EVV) valve
4. Vane pump (power steering)

The hydraulic pumps fitted in this model series were based on a modular design principle. Depending on the engine and equipment specification, a suitably dimensioned hydraulic pump is flange-mounted to the engine in the same installation space.

Decisive equipment features for these tandem pumps:

• Basic steering
• Integrated Active Steering (IAL)
• CO2 reduction measures
• Dynamic Drive (ARS)
• Dynamic Drive (ARS) and Integrated Active Steering (IAL)
• Intake restrictor valve

The hydraulic pump driven by the engine's poly-V belt is, on vehicles with Dynamic Drive, invariably a tandem pump, which consists of a radial-piston pump section for ARS and a vane pump section for the power steering.

Radial-piston pump section of the tandem pump

This radial piston pump has 8 pistons in a single row and is designed for a maximum pressure of 210 bar.

When the engine is idling, the pump speed is approximately 750 RPM. At that speed, the radial piston pump section delivers a minimum fluid flow rate of approximately 5.5 l/min at a pressure of approximately 3 bar.

Consequently an adequate fluid flow rate is guaranteed even at idling speed.

At a pump speed of 1450 RPM, the maximum fluid flow rate is limited to approximately 9 l/min.

New feature

As a CO2 reduction measure when driving in a straight line, the fluid flow rate of the radial piston pump is restricted by a restrictor valve on the intake side, thereby substantially reducing the circulation pressure and, therefore, the engine power used to drive the pump. As a result, active control of the intake restrictor valve makes a positive contribution to the CO2 equation.

The Dynamic Drive and hydraulic power steering share a common fluid reservoir and fluid cooler.

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