JPH03504710A - Electrohydraulic power steering system for automobiles - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Electrohydraulic power steering system for automobiles This invention relates to an electrohydraulic power steering system for automobiles. Involves a hydraulic power steering system and is steered by the driver. Measuring device, electronic control unit, flow rate to determine the torque applied to the shaft body supply unit, a switching valve having at least one switching valve; a lube assembly, a mechanical stem, and an actuating cylinder connected to a ring mechanism; according to the steering direction and controlled by the above switching valve assembly Pressure is applied to the working chamber of the working cylinder and the switching valve assembly is An electrohydraulic power steering system whose control is performed by the electronic control unit mentioned above. It concerns the stem.

This kind of power steering system is based on French patent specification 2.205.875. is already known.

In the above-mentioned known power steering system, the torque detection device is connected to the steering wheel. located on the plug shaft and connected to the electronic control unit, and connected to the electronic control unit. Furthermore, vehicle speed is input as another variable. The control pump receives these two inputs. Driven according to the value, this control pump operates the cylinder through a switching valve. It is connected to the corresponding working chamber of the da.

The electrofluidically controlled pressure fluid pump in the above application is structurally complex and In addition, such pumps are forced to incur higher costs. Use as a pressure fluid supply for systems is not permitted.

This invention aims to solve the above-mentioned drawbacks of conventional power steering systems. It is intended to be structurally simple and low-cost. It is something to do.

In particular, its components are those already proven in automotive fluid supply systems. should be used. This purpose is achieved by the configuration specified in Claim 1 of the present application. can be achieved.

According to the invention, a constant displacement pump for a vehicle, in particular a hydraulic brake system, is used. This makes it possible to use the fluid pressure supply unit in a wide variety of ways. this is for the pump Fluid with a fluid accumulator that is thus automatically maintained at a defined pressure level This is particularly advantageous in pressure brake systems.

In this invention, as a preferred embodiment, a hydraulic brake system is conveniently provided. , has brought a priority circuit. In the event of a failure in the pressure supply, the steering system The switching valve assembly is 2-way/2-position to ensure manual operation of the system. Contains directional control valves that are unenergized, open, and electronically It is operated by a control unit.

The power steering system of this invention uses existing fluid pressure components in a wide variety of ways. In addition to the use of In one embodiment of the invention, the electronic control unit controls the power steering system. At the same time, it also plays the role of anti-rotation control system and suspension control. plus one joint electronic control unit.

Furthermore, the functions and features of this invention are shown in the attached drawings and the following description. It will become clear.

Figure 1 is a schematic diagram of the power steering system, Figure 2 is an electronic anti-lock One embodiment of the invention combined with a brake brake system, FIG. FIG.

According to Figure 1. A power steering system according to an embodiment of the invention includes an electric motor A fluid consisting of a pump driven by a fluid pressure accumulator and a reservoir A pressure supply unit is provided. The pressure side of the above pump is connected to the proportional pressure via line 2. It is connected to the regulating valve 4, which has a three-way switching function and is connected to the other connecting line. The third boat is in communication with the fluid reservoir via connection line 3 and the third boat is actuated via connection line 5. It is connected to the cylinder 6 and/or the switching valve assembly 7. The above operation Cylinder 6 is connected to a mechanical steering mechanism as shown in FIG. .

At a branch point 8, a line portion 9 led to one working chamber 1o is connected to the line 5. ing. The line 5 itself is connected to the working chamber 11 of the working cylinder 6 and is connected to the first two sides. A direction/two-position directional control valve 12 connects the port of the working chamber 11 and the branch point 8. placed in between. This two-way/two-position directional control valve 12 and the actuation cylinder 6 In between, a reservoir line 14 is connected to said line 5 at its connection point 13. ing. The second two-way/two-position directional control valve 16 connects the connection point 13 to the The reservoir line 14 is inserted between the reservoir line 15 and the reservoir line 15 .

These two directional control valves 12 and 16 each have an open solenoid valve when not energized. It is designed as an idle valve, which generates electricity depending on the direction of rotation of the steering wheel. Switched by child control unit.

The working cylinder 6 is designed as a so-called differential cylinder, which means that the piston This means that the cross section of the rod reaches 50% of the cross section of the piston. working piston moves in the direction of the piston rod, the second two-way/two-position directional control valve 16 is closed and the first two-position directional control valve 12 is held in the open position. . On the other hand, when the piston rod moves in the opposite direction within the cylinder, the first two The position-directional control valve 12 is closed and the working chamber 11 is opened in the second two-way direction. /2 position directional control valve 16 communicates with reservoir 15 .

The piston rod has a working cylinder designed as a synchronized cylinder through which the rod passes through If you want to have a power steering system, the pressure surface of the piston should be in the re-actuation chamber. are each of equal size, thus creating a modified switching valve assembly. It is necessary to provide For example, each working chamber may include a pump and/or proportional pressure regulator. In the connection line leading to the control valve.

A 2-way/2-position directional control valve that is open in the inactive state and then released. Two ends of the connection line leading to the server that are closed in the inactive state It is necessary to provide each of the above-mentioned chambers with a directional/two-position directional control valve.

The proportional pressure regulating valve 4 is likewise actuated by the electronic control unit 17, i.e. 8 It is activated by the amount of torque applied to the steering wheel. The above electric The slave control unit 17 is connected to a torque sensor attached to the steering wheel. , are connected by an electrical connection 18, and the sensor detects the magnitude of torque and rotation. The direction is detected and a corresponding input signal is provided to the electronic control unit 17.

The electronic control unit 17 connects the battery and the battery via electrical connections 19 and 20, respectively. The power steering system, including the pump, is connected to the , can only be operated when the ignition is turned on. operation and electrical connections (not shown) for monitoring are connected to the electronic control unit 17. It is provided between the fluid pressure supply unit and the fluid pressure supply unit. This allows each steering operation When the pump is switched on, only a very small amount of fluid is It is always drawn from the hydraulic accumulator.

A common fluid pressure supply unit supplies the power steering system as shown in Figure 2. When used together with systems and other fluid pressure systems installed in automobiles, advantageously, the electronic control unit 17 can, for example, in the event of a pump failure, This prevents smaller systems from becoming activated, thereby Abbreviation for ``sumulator'', the entire amount of which will be used by higher priority systems. P, 7. par, 3 electromagnetically operable proportional pressure regulating valve, electronic control unit 1 A fluid pressure proportional to the electrical output signal of 7 is metered into line 5.

This electrical signal is the torque determined by the torque sensor on the steering shaft. Not only according to the magnitude of It is further influenced by control variables. This control variation element is, for example.

Vehicle speed, longitudinal and lateral acceleration, drive torque and braking applied to the front and rear axles. These include the distribution of torque, the load on the car, and changes in the above-mentioned loads applied to each axle.

This allows the above-mentioned hydraulic power steering system to meet the special requirements of automobiles. Items can be matched, e.g.

When the driving speed is low, the steering power is the same as that at high speeds. increases compared to the operating power.

Combining various electronic control systems is a hydraulic power steering system This steering system not only helps in adjusting the It is possible to influence the system as well.

Figure 2 shows hydraulic power steering combined with an electronically controlled anti-lock brake system. This shows the ring system, and its design and function are basically as shown in Figure 1. This corresponds to that of the embodiment described above. A pump 21 and a motor driven by a motor 22 The accumulator 23 and reservoir 14 are used for brake and auxiliary power steering. It serves as a joint supply unit for the system.

A torque sensor 24 is arranged on the steering wheel hub, for this purpose It has a small torsion angle of approximately ±2° at maximum torque and has a centering function. A six-member member having elasticity in the direction of rotation is provided, and the member has a potentiometer. Activate the meter.

Of course, a torque conversion device based on a strain measurement piece can be used as well.

The proportional pressure regulating valve 4 and the switching valve assembly 7 are connected to the valve block 25. Built-in. The electrical connection line 26 is connected to the electric motor 22 and In 27 is provided for monitoring the pump. 28 groups of electrical connection lines are determined for input/output of other control variable elements, and these various electronic control Systems are enabled to influence each other in appropriate ways.

The details of the proportional pressure regulating valve 4 are as shown in FIG.

The valve consists essentially of an electromagnetic actuator 29 and a shaft housed within a housing 30. directional slide 31, and the electromagnetic actuating device 29 has a proportional magnet. , when the magnet is energized, the axial slide 31 is in the illustrated inoperative state. It is moved from position to position using a force proportional to the current.

Reset spring 32 is compressed during this movement. The axial slide 31 is As long as it is in the inactive position, the supply port 33 communicating with line 5 is connected to connecting line 3. It is connected to the connected reservoir port 34.

A pump port 35 communicating with the pump outlet via line 2 is connected to the axial slider. 31, thereby minimizing leakage.

Due to the force of the proportional magnet opposing the force of the reset spring 32, the axial direction When the facing slide 31 moves, first.

The connection between supply port 33 and reservoir port 34 is closed, and then the pump The port 35 has a radial bore 36. Via the axial bore 37 and the second radial bore 38 and connects to the supply port 33.

The pressure created in the supply port 33 acts on the axial slide 31 and Opposing the magnetic force of the magnet. This fluid pressure reaction force is generated within the axial bore 37. This pressure is achieved by means of a pin 39 that slides closely into the housing. It can be received by a closure screw 40.

The small cross-sectional area of the bottle allows the use of relatively small magnets. above Accurate pressure regulation at the feed port 33 is achieved by adjusting the pressure applied to the axial slide 31. This can be done by compensating the magnetic force which can be adjusted by. two electric switches The switch 41 serves to monitor the end position of the slide.

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international search report

Claims (8)

[Claims] (1). Determines the torque applied to the steering shaft by the driver a measuring device, an electronic control unit, a fluid supply unit, at least one Switching valve assembly with switching valve, mechanical steering The above switching valve assembly is connected to the mechanism and according to the direction of steering. an actuating cylinder to which a controlled pressure is applied to its actuating chamber; An electro-hydraulic power source in which the control of the valve assembly is carried out by the electronic control unit mentioned above. -In the steering system, The fluid supply unit (1, 15, 21, 22, 23) and the operating cylinder (6 ), the proportional pressure regulating valve is connected to the above electronic control unit. an electrohydraulic power steering wheel, characterized in that it is arranged to be operable by system. (2). one or more fluid systems, especially fluids, for supplying fluids; The supply unit (15, 21, 22, 23) in the brake system is Claim (1) characterized in that the power steering system is connected to the power steering system. Electrohydraulic power steering system as described. (3). characterized in that the actuating cylinder is designed as a differential cylinder. The electrohydraulic power steering system according to claim (1). (4). Said switching valve assembly (7) comprises two electromagnetically operable 2 directional/two-position directional control valves (12, 16), these valves are not energized. Any one of claims (1) to (3), characterized in that it is released in a state of Electro-hydraulic power steering system as described in Section. (5). The electronic control unit (17) controls the power steering system and the a lock brake system; The electrohydraulic power steering system according to any one of requirements (1) to (4). Tem. (6). The electronic control unit (17) is connected to the power steering system. Features a Q-lock brake system and serves as suspension control The electrohydraulic power steering wheel according to any one of claims (1) to (5). system. (7). A priority circuit ensures that said braking system is always given priority. According to any one of claims (1) to (6), the Electrohydraulic power steering system. (8). Claim characterized in that the brake fluid is used as pressure fluid ( The electrohydraulic power steering system according to any one of 1) to (7).