JPH0629037B2 - Full hydraulic power steering device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of an all-hydraulic power steering system for a power steering system such as an agricultural tractor or a forklift, which has a steering mechanism composed of a hydraulic circuit.

[Conventional technology]

Conventionally, as an all-hydraulic power steering device, the one disclosed in Japanese Patent Laid-Open No. 49-94028 is known. This is a valve body 1 as shown in FIG.
A cylindrical sleeve 2 is mounted inside, and a spool 3 that is connected to the handle is mounted inside the sleeve 2. And
A metering pump 4 is attached to one end of the valve body 1, and a rod 5 for rotating a rotor of the pump 4 is arranged in the spool 3, and the rod 5, the spool 3,
The sleeve 2 is pin-connected, and the metering pump 4 is driven by operating the handle. Such a valve device is connected to the hydraulic pump 6 and the tank 7, and is also connected to the power cylinder 8, and distributes the pressure oil measured by the metering pump 4 to the cylinder port by operating the handle, and from the cylinder port. Return oil of tank 7
Reflux to.

[Problems to be solved by the invention]

However, according to the conventional all-hydraulic power steering device, the configuration of the metering valve A portion provided for distributing the metered pressure oil and for returning the return oil is 5th to 7th.
As shown in the figure, there is a problem that it becomes extremely complicated and it is extremely difficult to maintain high accuracy. That is, oil passages, ports, and communication passages must be provided on the inner peripheral surface of the valve body 1, the inner and outer surfaces of the sleeve 2, and the outer peripheral surface of the spool 3, and these must be formed on the circumferential surface. I won't. If these processing precisions are poor, oil leakage will occur and switching of the oil passages will not be satisfactory, resulting in deterioration of the power steering operability. Therefore, it is necessary to introduce specialized processing equipment and perform high-precision machining, but in reality, it is difficult to secure high accuracy because it is a machining on a cylindrical surface, which is a demerit in terms of manufacturing cost. Atsuta Further, in the layout of the above-mentioned conventional hydraulic power steering system, as shown in FIG. 8, the control valve is arranged on the steering wheel side, the hydraulic pump 6 and the power cylinder 8 are arranged in the front part of the engine, Pump 6
And a power cylinder 8 are connected by a long pipe 9. However, the length of the piping is increased, the resistance of the piping is increased, and energy loss is accompanied, resulting in a large loss device configuration.

The present invention focuses on the above-mentioned conventional problems, has a simple valve structure etc. without providing a complicated hydraulic passage, and separates the operating side and the hydraulic drive side to shorten the length of the hydraulic pipe line, It is an object of the present invention to provide an all-hydraulic power steering device that can reduce the current flow loss of the.

[Means for solving problems]

The present invention for solving the above-mentioned problems includes an operation mechanism including an operation side torsion bar that is connected to a handle side and is rotatably supported, and an output side torsion bar that is connected to the torsion bar via gear means. And a metering pump driven by the output side torsion bar and the motor, the metering pump is arranged in the oil passage between the hydraulic pump and the steering power cylinder, and both ends of the oil passage are connected to and disconnected from each other. A hydraulic drive unit provided with a control valve having a proportional solenoid is provided, and the steering mechanism unit is provided with a steering angle sensor for detecting a rotation angle of the operation side torsion bar with a neutral point as a reference. When the detected rotation angle becomes larger than a certain value, the motor and the proportional solenoid of the hydraulic drive unit are based on the detected value. It is a fully hydraulic power steering apparatus having a controller for driving.

[Action]

With the above configuration, it is possible to drive the motor and the control valve of the hydraulic drive unit based on the steering angle detection value in the operation mechanism unit, and to feed the metered hydraulic oil to the power cylinder. The hydraulic drive section can be separated from the hydraulic drive section, and the hydraulic pipe line can be shortened. By separating the operating mechanism part and hydraulic drive part, the metering pump structure and the control valve structure can adopt the conventional general structure, and a complicated hydraulic passage must be provided. Without, metering and valve structure can be simplified. Further, since hydraulic piping is required only by the hydraulic drive section, piping to the operation mechanism section is unnecessary, and energy loss such as pipeline loss can be reduced.

Further, when the rotation angle detected by the steering angle sensor is smaller than a certain value, the controller does not drive the motor of the hydraulic drive unit and the proportional solenoid based on the detected value. Therefore, if this constant value is set to an appropriate value, there is no possibility that the rudder angle sensor picks up the rattling caused by the assembly error that occurs during the assembly work of each member and causes the power cylinder to malfunction. Therefore, according to the present invention, it has a simple valve structure and the like, the hydraulic pipeline is shortened, the oil flow loss is reduced, and at the same time, due to the assembly error that occurs during the assembly work of each member. It is possible to provide a safe all-hydraulic power steering device in which the power cylinder does not malfunction due to rattling.

Example of Invention

Embodiments of an all-hydraulic power steering device according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an overall configuration diagram of the embodiment apparatus. This device has an operating mechanism portion 11 directly connected to the handle 10. The operation mechanism unit 11 includes a pair of torsion bars 12A, 1
2B is rotatably supported, and a large gear 13 is attached to both ends of one torsion bar 12A, and a small gear 14 is attached to both ends of the other torsion bar 12B. The large and small gears 13 and 14 are meshed with each other. . Gear 13
Handle bar 12A is attached to handle bar 10
The rotation operation of the handle 10 is directly transmitted to the corresponding torsion bar 12A, and is transmitted to the other torsion bar 12B through the gears 13 and 14.

A steering angle sensor 15 and a mechanical stopper 16 are attached to the input shaft portion of the handlebar 10A of the operation side torsion bar 12A connected to the handlebar 10,
The steering angle of the steering wheel 10 is detected and the maximum turning angle of the steering wheel 10 is limited. As shown in FIG. 2, the rudder angle sensor 15 is provided with resistors 18 _R and 18 _L which are bilaterally symmetrical with respect to the insulator 17 placed at the neutral point.
The insulators 17 and the resistors 18 _R and 18 _L are arranged in an arc, and the slider 19 that rotates following the steering of the steering wheel is brought into contact with the resistors 18 _R and 18 _L and applied from the constant power sources 20 _R and 20 _L. varying voltage V _R corresponding to the steering angle of the _voltage, and to detect the V _L.

A hydraulic drive unit 21 is connected to the operation mechanism unit 11 via an output shaft of a small gear 14. This hydraulic drive unit 2
1 is a small gear 1 coaxial with the output side torsion bar 12B
It has a metering pump 23 that is driven by being connected to the output shaft section 4 and the electric motor 22. A positive displacement rotary pump is used as the metering pump 23,
A vane type pump as shown in the schematic view of FIG. 3 can be used. The metering pump 23 measures the hydraulic oil supplied from the hydraulic pump 24 and sends it to the power cylinder 25. The hydraulic drive unit 21 includes a control valve 26 provided between the metering pump 23, the hydraulic pump 24, and the power cylinder 25.
Is provided. The control valve 26 connects the hydraulic pump 24 and the tank 27 at a neutral position to form a return passage, and cuts the oil passage between the metering pump 23 and the power cylinder 25. , The hydraulic pump 24 and the metering pump 23 are connected, and the flow passage between the metering pump 23 and one cylinder chamber of the power cylinder 25 is opened, and at the same time the flow passage between the other cylinder chamber and the tank 27 is opened. To switch to. The switching operation is performed by moving the valve spool, and the power cylinder 2
5, the steering direction of the steered wheels 28 is determined. In order to provide this valve spool action, the control valve 26 has a proportional solenoid 29 across its ends.
It has A and 29B. Therefore proportional solenoid 2
By applying a drive signal to 9A and 29B, the valve switching operation is performed and steering becomes possible.

Here, a controller 30 is provided in the device in order to apply a drive signal to the motor 22 of the hydraulic drive unit 21 and the proportional solenoids 29A and 29B.
0 outputs a drive signal based on the detection signal from the steering angle sensor 15 of the operation mechanism section 11. That is, the controller 30 determines the types V _R and V _L of the detection signal from the steering angle sensor 15 and determines the rotation direction of the motor 22 and the proportional solenoids 29A and 29B to be operated. The signal _V R, proportional to the amount of rotation of Yotsute motor 22 to the size of the _{V L} solenoid 29A, is cause to determine the actuation amount of 29B.

The operation of the thus-configured full-hydraulic power steering system is as follows. First, when the control valve 26 is in the neutral state, the circuit is blocked on both the suction side and the discharge side of the metering pump 23. At this time, when the steering wheel 10 is steered, the metering pump 23 has steering resistance, so that the meshed output side gears 13 and 14 do not move, and the operation side torsion bar 12A is twisted, and the output side large gear 13 and the handle shaft are connected. Relative angular displacement occurs between the two, and the steering angle sensor 15 generates a steering angle signal. In FIG. 2, there is no signal output in the range of the steering angle θ ₁ because the output terminal of the sensor 15 is insulated, but since the operation side torsion bar 12A is twisted in the range of θ ₁ , this is the steering reaction force. Becomes

The rotation torque T _i required to rotate the metering pump 23 with the control valve 26 in the ON state is supplied by the manual input torque kθ ₂ r and the motor torque T _M at the output small gear shaft of the output side torsion bar 12B. . Note that k is a coefficient, θ ₂ is a twist angle of the torsion bar 12A, and r is a cross-sectional radius of the torsion bar 12B. At this time, the steering angle sensor signal corresponding to (θ ₂ -θ _{1) V R}
( _VL ) is processed by the controller 30 and becomes a drive signal for the proportional solenoid 29A (29B) of the control valve 26. By this signal, the control valve 26 is activated, and the metering pump 23 has the power cylinder 2
Pressure oil is sent according to the load acting on 5, and the amount of oil according to the handle rotation angle is metered and sent to the power cylinder 25 via the control valve 26. When the load on the power cylinder 25 increases, the required rotational torque of the metering pump 23 increases, so that the torsion angle of the operation side torsion bar 12A increases and the steering angle sensor signal V _R (V _L ) increases. Proportional solenoid 29A (29
B) As a result of the increased drive voltage, the control valve 26
The pressure generated at will increase. Therefore, the drive side pressure of the metering pump 23 also rises, and the pressure oil commensurate with the increased load pressure is supplied to the power cylinder 25.

During the above-described operation, the rotation speed of the metering pump 23 is set to the handle 1 via the reduction gear mechanism including the operation side torsion bar 12B and the input side gears 14 and 13.
It is associated with 0 rpm.

As described above, according to this embodiment, even with the small capacity metering pump 23 having a simple fixed capacity, the basic discharge amount (per one rotation of the handle) can be selected by selecting the gear ratio of the speed increasing gear and the rotation speed of the motor 22. It is possible to secure the variation of the discharge amount). Further, since the commutator valve mechanism is unnecessary, the structure of the control valve 26 can be simplified and the processing cost can be suppressed. Further, in the embodiment, the operation mechanism unit 11
By separating the hydraulic drive unit 21 and the hydraulic drive unit 21 from each other, the operation mechanism unit 11 can be disposed on the driver's seat side of the vehicle, and the hydraulic drive unit 21 can be disposed near the hydraulic power source on the front axle side of the vehicle. The length can be extremely shortened, the flow loss of hydraulic oil can be reduced, and the responsiveness can be improved.

〔The invention's effect〕

According to the present invention described above, a simple valve structure or the like is provided, the hydraulic pipe line is shortened, and the oil flow loss is reduced, but at the same time, the assembly error caused during the assembly work of each member is prevented. It is possible to provide a safe all-hydraulic power steering device in which the power cylinder does not malfunction due to rattling.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an all-hydraulic power steering device of an embodiment, FIG. 2 is a circuit diagram of a steering angle sensor, FIG. 3 is a schematic configuration diagram of an operating pump, and FIG. 4 is a cross section of a valve mechanism portion of a conventional example. 5 and 5 are sectional views taken along line VV of FIG. 4, FIG. 6 is a side view of the sleeve, FIG. 7 is a side view of the valve spool, and FIG. 8 is a vehicle layout view. 10 ... Handle, 11 ... Operating mechanism, 12A, 12
B ... Torsion bar, 13, 14 ... Gear, 15 ...
Steering angle sensor, 21 ... Hydraulic drive unit, 22 ... Motor, 2
3 ... Metering pump, 24 ... Hydraulic pump, 25
...... Power cylinder, 26 …… Control valve, 2
9A, 29B ... Proportional solenoid, 30 ... Controller.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsunefumi Arita 2548 Tsuchida, Kani City, Gifu Prefecture Gifu North Factory, Kayaba Industrial Co., Ltd. (56) Reference JP-A-57-95256 (JP, A) JP-A-57 -99471 (JP, A)

Claims (1)

[Claims] 1. An operation mechanism section comprising an operation side torsion bar, which is connected to a handle side and is rotatably supported, and an output side torsion bar, which is connected to the torsion bar via gear means. A metering pump driven by a side torsion bar and a motor, and a control valve having the metering pump arranged in an oil passage between a hydraulic pump and a power cylinder for steering, and having proportional solenoids at both ends for intermittent switching of the oil passage. A steering angle sensor for detecting the rotation angle of the operation side torsion bar with respect to the neutral point is provided in the operation mechanism section, and the rotation angle detected by the steering angle sensor is constant. When it becomes larger than the value, a controller that drives the motor and the proportional solenoid of the hydraulic drive unit based on the detected value. All hydraulic power steering apparatus equipped.