JPH0328349B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a power steering device in which a pump for the power steering device is driven by an engine.

<Prior art> In a vehicle equipped with a power steering device, it is necessary to prevent the engine speed from decreasing due to an increase in engine load when the power steering device is operating, resulting in a knocking state or stopping. There is a need. For this reason, conventionally, as shown in FIG. 1, an air control valve 3 is provided in an oil passage connecting the power steering device main body 1 and the hydraulic pump 2, and is operated by the pressure increase when the power steering device main body 1 is operated. and a negative pressure actuator 6 that increases the opening degree of the throttle valve 5 of the carburetor. The opening of the slot valve 5 is increased when the power steering device main body 1 is in operation, thereby increasing the engine output.

However, there is a delay in the operation of the negative pressure actuator 6 and the engine 7, making it difficult to rapidly increase the engine output. If the load increases smoothly, the engine output can be increased in time, but when the piston 9 of the power cylinder 8 has moved to a position close to the stroke end, the handle operation is temporarily stopped, and from this state, the handle operation cannot be restarted. If the piston 9 reaches the stroke end and reaches the steering end, the engine output may not increase in time, and the engine may knock or stop.

In other words, once the steering wheel operation is stopped, the power steering device main body 1 becomes inactive and the engine 7 idle up is released, so the air control is activated in response to the steering wheel operation from this state. Even if the valve 3 operates, it takes time to increase the engine output, and the steering end is reached before the increase in engine output is completed, increasing the load on the pump 2. As a result, the rotation speed decreases due to the decrease in engine speed. This may lead to instability and rotational stoppage.

<Objective of the Invention> Therefore, the present invention reduces the ratio of power transmission between the engine and the pump in the vicinity of the steering end, and reduces engine rotation by rapidly increasing the pump load at the steering end. The purpose is to prevent the system from becoming unstable or stopping.

<Structure of the Invention> The present invention includes a clutch disposed between an engine and a pump, a steering angle detection means for detecting a steering angle of a steering handle connected to the power steering device, and a steering angle detection means for detecting a steering angle of a steering handle connected to the power steering device; An idle up mechanism that increases engine output with an activation delay when activated, and a control means that operates the clutch in the opening direction near the steering end of the steering handle in response to the output of the steering angle detection means. It is characterized by:

<Examples> Examples of the present invention will be described below based on the drawings. In FIG. 2, 10 is an engine, and 11 is a pump driven by this engine 10, between a pulley 12 attached to the output shaft of the engine 10 and a pulley 13 attached to the input shaft of the pump 11. A belt 15 is passed over the
An electromagnetic clutch 16 is interposed between the input shaft of the pump 11 and the pulley 13. The electromagnetic clutch 16 has a transmission torque that changes in proportion to the excitation current, and is, for example, a powder clutch.

On the other hand, 20 is a power steering device main body operated by pressure fluid discharged from the pump 11. This power steering device main body 20 includes a power cylinder 22 containing a built-in power piston 21 connected to a steering mechanism on the wheel side, and a power cylinder 22 connected to the power piston 21 via a rack and pinion mechanism 23, and an input shaft that is used for steering. Steering handle 2 via shaft 26
The pressure fluid discharged from the pump 11 is supplied to the servo valve mechanism 27 via a pipe 19. When the steering handle 25 is not operated, the pressure fluid discharged from the pump 11 is returned directly to the tank, and when the steering handle 25 is operated, the pressure fluid is sent to the left and right chambers of the power cylinder 22 according to the steering direction. It acts to move the power piston 21 by supplying it to either of the two.

Next, I will explain the idle up mechanism.
A throttle valve 32 is disposed in the carburetor 31 connected to the engine 10 via the intake manifold 30, and the throttle valve 32 is rotated in the direction to open the throttle valve 32 when the rear chamber 33a becomes negative pressure. A negative pressure actuator 33 is connected thereto. The rear chamber 33a of this negative pressure actuator 33 is communicated with the intake manifold 30 via an air control valve 35.

The air control valve 35 was developed in 1986.
The air control valve 35 is of the type shown in FIGS. 3 and 4 of Publication No. 8984, and the fluid inlet 35a of the air control valve 35 is connected to the middle of the pipe 19, and the pump 11 is controlled by operating the steering handle 25. When the discharge pressure increases, the spool within the air control valve 35 moves to communicate between the ports 35c and 35b, thereby communicating the rear chamber 33a of the negative pressure actuator 33 with the intake manifold 30. As a result, the diaphragm of the negative pressure actuator 33 compresses the spring and moves toward the rear chamber 33a, rotating the throttle valve 32 in the direction to open it and increasing the engine output.

On the other hand, the control circuit 40 is a control circuit that reduces the power transmission rate by the electromagnetic clutch 16 when the power piston 21 reaches the vicinity of the stroke end, that is, when the steering handle 25 approaches the steering end, and 45 is a gear mechanism. Steering shaft 2 via 46
6 is a potentiometer forming a position detector.

The control circuit 40 includes a potentiometer 45.
An AD converter 41 is provided to convert the output of the AD converter 41 into a digital value, and the output of the AD converter 41 specifies a memory address of a read-only memory 42 that stores the drive current value. and,
The drive circuit 4 converts the drive current value data read from the read-only memory 42 into an analog command signal by the DA converter 43, and uses the output of the DA converter 43 to drive the solenoid of the electromagnetic clutch 16.
4. Therefore, when the steering wheel 25 is operated, a memory address corresponding to the steering angle of the steering wheel 25 is specified, and the electromagnetic clutch 16 is activated according to the drive current value stored in this specified address. The solenoid is excited, and the transmitted torque is changed according to this drive current value.

The read-only memory 42 stores the steering handle 25 within a predetermined angle range (-θL) as shown in FIG.
<θ<+θL), the drive current takes a constant high value, and when the drive current is steered beyond this angle range, it gradually decreases as it approaches the steering end ±θE. Current value data is stored. Therefore, the torque transmitted by the follower electromagnetic clutch 16 decreases as the steering end approaches ±θE, and the transmitted torque reaches a value close to zero at the steering end ±θE.

In the device configured as described above, when the steering handle 25 is operated with the power piston 21 located near the center, the air control valve 35 is activated due to an increase in the pressure on the discharge side of the pump 11. As a result, the idle speed of the engine 10 increases, and the engine output increases. Further, in this case, since the steering angle θ of the power piston 21 is in the range of -θL and +θL, the output of the control circuit 40 becomes a large value, the electromagnetic clutch 16 is in a high torque connection state, and the pump 11 is maintained at a steady speed. be rotated. As a result, appropriate power assistance is provided, and the engine 10 is prevented from stopping or the idling speed becoming unstable.

On the other hand, when the power piston 21 approaches the stroke end to a certain distance and the steering angle θ of the steering handle 25 reaches −θL and +θL, the control circuit 4
The drive current output from 0 gradually decreases and reaches a value close to zero at the steering end. As a result, the engine 10 is almost disconnected from the pump 11, and the load of the pump 11 hardly acts on the engine 10. In this state, the operation of the pump 11 is stopped, so that no pressure fluid is discharged from the pump 11, and the power assist action of the power steering device main body 20 no longer occurs, and the steering wheel becomes heavy. However, the range of steering angles in which the power assist effect decreases is a small angle range near the steering end, so it is hardly affected during normal steering, and this does not cause discomfort to the driver. do not have.

Then, the steering handle 25 is placed near the steering end.
By temporarily stopping the operation and then suddenly operating the steering handle 25 again, the rotation of the engine 10 will not become unstable or stop even if the steering end is reached.

It goes without saying that the present invention can also be applied to a recirculating ball type power steering device.

<Effects of the Invention> As described above, in the present invention, the clutch is disposed between the engine and the pump, and
a steering angle detection means for detecting a steering angle of a steering wheel connected to the power steering device; an idle-up mechanism for increasing engine output with an operation delay when the pump is activated; Since the configuration includes a control means for operating the clutch in the opening direction near the steering end of the steering handle in response to the output, the pump is disconnected from the engine near the steering end;
This eliminates the conventional problem where the pump reaches the steering end before the increase in engine output is completed, causing a load on the pump, and the engine load does not increase rapidly even at the steering end, which prevents engine rotation from becoming unstable. It has the advantage of not having to stop or stop.

[Brief explanation of the drawing]

Fig. 1 shows a conventional power steering device, Figs. 2 and 3 show an embodiment of the present invention, and Fig. 2 shows an embodiment in which the present invention is applied to a vehicle equipped with a mechanical carburetor. The overall configuration diagram shown in FIG. 3 is a diagram showing changes in the output of the control circuit 40 in FIG. 2. 10...Engine, 11...Pump, 16...
Electromagnetic clutch, 20...Power steering device main body, 22
...Power cylinder, 25...Steering handle, 4
0...Control circuit, 41...AD converter, 42...
Read-only memory, 43...DA converter, 44...
Drive circuit, 45... Potentiometer, 46...
Gear mechanism.

Claims (1)

[Claims] 1. In a power steering device in which a pump for the power steering device is driven by an engine, a clutch is disposed between the engine and the pump, and a steering wheel connected to the power steering device is provided. a steering angle detection means for detecting a steering angle of a steering wheel; an idle up mechanism for increasing engine output with an operation delay when the pump is activated; and a steering angle detection means for steering the steering wheel in response to an output of the steering angle detection means. A power steering device characterized in that it is provided with a control means for operating the clutch in the opening direction near the end.