JPH02262469A - Power steering device for vehicle - Google Patents

Abstract

PURPOSE:To increase the rotation resistance of a steering handle and perform safe driving by carrying out the duty on/off control of a control valve provided between a flow control valve with an overload relief valve and a controller at the time of detecting the high speed condition of a vehicle. CONSTITUTION:The main portion of the hydraulic system 40 of power steering is formed with a hydraulic pump 38, a flow control valve 41 with an overload relief valve and a controller 13. A control valve 46 having a solenoid 48 so as to be duty controlled is provided between the flow control valve 41 and the controller 13. A speed detector 34 detects the speed condition of a vehicle and, at the time of detecting the high speed condition of the vehicle, the control valve 46 is controlled so as to carry out the duty on/off of oil pressure to the controller 13 by a control means 47 having a solenoid driving circuit. Thereby, the rotor 44 of the controller 13 is made function as a hydraulic pump to increase the rotation resistance of a steering handle 24.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a power steering device for a vehicle, and is used for a wheel-type layered tractor or the like.

(Prior Art) As a power steering device that reduces the operation of a steering wheel, there is a technology disclosed in Japanese Utility Model Application Publication No. 60-24671, for example.

(Problem to be solved by the invention) However, in the conventional case, the rotational resistance of the steering wheel is small and constant regardless of whether the vehicle speed is high or low, so when driving at high speed, the steering wheel is taken, resulting in meandering driving. , there was a problem that safe high-speed driving was no longer possible.

Therefore, in order to solve the above problem, the present applicant provided a relief valve capable of controlling the relief pressure in the hydraulic circuit of the power steering, and also provided a speed detector for detecting the speed state of the vehicle. A technology (hereinafter referred to as the proposed technology) in which a control means is provided to control the relief valve so that the relief pressure is reduced when the device detects a high speed state is disclosed in Japanese Patent Application Nos. 63-168280 and 1983-16.
This is proposed in No. 8281.

However, this proposed technology controls the power steering system pressure by changing the set pressure of the relief valve, which not only causes an increase in oil temperature, but also causes energy loss. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power steering device for a vehicle that solves the problems of the prior art described above and also solves the only problem of the proposed technology.

(Means for Solving the Problems) The present invention provides a power steering hydraulic system 40 comprising a hydraulic pump 38, an overload relief rotary flow control valve 41, and a controller 13 using the following techniques to achieve the above-mentioned objects. We are taking appropriate measures.

That is, the present invention provides a duty-controlled control valve 46 between the flow rate control valve 41 and the controller 13, and a speed detector 34 for detecting the speed state of the vehicle. The present invention is characterized in that a control means is provided which controls the duty control valve 41 to turn on/off the hydraulic pressure to the controller 13 when a state is detected.

Further, the present invention provides the flow rate control valve 41 and the controller 1.
A proportional control valve 46A that is proportionally controlled is provided between the
A speed detector 34 is provided to detect the speed state of the vehicle, and when the speed detector 34 detects a high speed state, the proportional control valve 46A is controlled in proportion to the speed to proportionally control the hydraulic pressure to the controller 13. It is characterized in that it is provided with a control means for controlling.

(Function) When the vehicle is running and the running speed reaches a predetermined high speed state, the speed detector 34 detects this.

According to the first technical means of the present invention, this detection signal is used to control the duty control valve 46 from on to off by the control means (solenoid drive circuit 47).

As a result, the hydraulic pressure acts on and off on the controller 13 in a duty manner, and the gerotor 44 functions as a hydraulic pump, and as a result, the rotational resistance of the handle 24 becomes considerably large.

On the other hand, the flow rate control valve 41 has no relief function and drains the oil from the hydraulic pump 38 to the hydraulic tank 39, where it suppresses the rise in oil temperature.

Further, according to the second technical means of the present invention, the proportional control valve 46A is proportionally controlled according to the vehicle speed based on the signal from the detector 34, thereby increasing the rotational resistance of the handle 24.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 3 shows an independent cabin type tractor as an example of a vehicle. In FIG. 3, reference numeral 1 denotes a tractor body, which is composed of an engine 2, a transmission case 3, and the like. 4 is a front axle frame attached to the engine 2; 5 is a front axle case, which is suspended on the front axle frame 4 via a center bin; front wheels 6 are provided on both the left and right sides of this front axle case 5; There is.

7 is a power cylinder for front wheel steering, which is attached to the rear of the front axle case 5. 11 is a radiator, 12
is the bonnet that covers the second engine. 13 is a fully hydraulic steering controller for controlling the cylinder 7, and is connected to the cylinder 7 via hoses 14 and 15.

16 is a rear wheel, and 17 is a rear wheel fender. Reference numeral 18 denotes an independent cabin, which has doors 19 on both left and right sides.
An instrument panel 23 and a steering handle 24 are provided on the second side, respectively, and are removably mounted on the vehicle body 1 from above via a mount rubber or the like.

The handle 24 is supported by a handle post 26 via a handle shaft 25, and the handle post 26 is attached to a support frame 27 within the instrument panel 23 via a vibration isolator. The handle shaft 25 has a joint 28 and a shaft 29.
, a joint 30, a shaft 31, and a joint 32, the input shaft 33 of the controller 13 is interlocked.

34 is a speed detector attached to the vehicle body 1, and the figure shows a ground speed radar sensor.

FIG. 1 shows a hydraulic system for power steering, and FIG. 2 shows a schematic plan view of a fully hydraulic power steering system.

In FIG. 2, reference numeral 35 denotes steering arms, which are connected to each other by tie rods 36 and to an operating arm 37.
The actuating arm 37 is actuated by the power cylinder 7,
The front wheels 6 are steered.

A hydraulic pump 38 is driven by the engine 2 and sends oil to the oil pressure controller 13 of the oil tank 39 and to the cylinder 7 via hoses 14 and 15.

In FIG. 1, 40 is a power steering hydraulic system, including a pump 38, an overload relief valve closing flow control valve 4
1. The controller 13 controls the power cylinder 7 by operating the handle 24, and includes a check valve 42, a 6-boat/3-position switching valve 43, and a gerotor 44. When the handle 24 is rotated, the switching valve 43 of the controller 13 is switched from the neutral position shown in FIG. switching valve 43 and gerotor 44
A desired amount of fuel is supplied to the power cylinder 7 via the power cylinder 7, the power cylinder 7 is operated, and the front wheels are steered by a desired angle by a light operation of the handle 24.

Note that 45 is a check valve for protecting the pump, and 39A is a filter.

Reference numeral 46 denotes an electromagnetic duty control valve, which is provided between the overload relief valve sealing control valve 41 and the controller 13, and is used to ensure that the speed detector 34 maintains the vehicle speed at a predetermined high speed state. When this detection signal is detected, the 6th and 7th
The solenoid 4 is connected to the solenoid 4 via the solenoid drive circuit 47 shown in the figure.
8, and the duty is controlled from on to off. That is, as shown in FIGS. 6 to 8, the drive circuit 47 controls on/off the current flowing through the solenoid 48, and the duty ratio t/T of the control valve 46 is determined by the detector 3.
4 is increased in proportion to the detected speed.

FIG. 5 shows a tractor transmission, and 49 is a t-clutch that connects and connects the power of the engine 2 to the propulsion shaft 50.

Reference numeral 51 denotes a main transmission, 52 a super reduction gear, and 53 a sub-transmission. Through these, transmission is transmitted to a differential gear 55 via a rear wheel differential drive shaft 54, and transmitted to the rear wheels 16 via a final gear 56. Driven. The front wheel system has a 7-differential drive shaft 54 and a propulsion shaft 57 interlocked by a gear train 58, and a front wheel differential device 5.
9 and drives the front wheels 6 via the final gear 60.

In this FIG. 5, a detector 34 represented by a rotation sensor is provided on each of the rear axles 61, and a solenoid drive circuit 47 is driven as shown in FIG. 7 based on the difference in rotation speed between the two, or similarly, A rotation sensor is provided on the front wheel shaft 62 to detect high speed conditions.

Note that the detector 34 may be provided on all of the front and rear wheels.

Furthermore, as shown in FIG. 4, the high speed position of the shift fork 64 shifted by the main shift lever 63, for example 4th gear, may be detected by the detector 34 indicated by a limit switch, Detection may also be performed at the gear shift height.

Further, in FIG. 9, the control valve 46A is an electromagnetic proportional valve, which turns on and off the detection signal of the detector 34 in proportion to the vehicle speed.1. The rest is the same as the embodiment described above, and common parts are indicated by common symbols.

In the embodiment, a non-low reaction 1 cylinder type power steering is shown, but a low reaction 2 cylinder type, an index type, or a booster type may be used.

(Effects of the Invention) The present invention is as described above, and according to the first feature of the present invention, a duty-controlled control valve is provided between the flow rate control valve and the controller, and the speed state of the vehicle is controlled. A speed detector is provided for detecting a high speed state, and a control means is provided for controlling the duty control valve to turn on/off the hydraulic pressure to the controller when the speed detector detects a high speed state. When the vehicle is at high speed, the duty control valve of the hydraulic system is duty-controlled, and the hydraulic pressure is turned on and off to the controller on a duty-by-duty basis, so the resistance to turning the steering wheel increases, and the operator senses this, causing the vehicle to meander. can be prevented and safety can be improved.

In addition, when the switching valve is turned off, the oil from the pump is only drained through the flow control valve and no relief pressure is applied, so there is no rise in oil temperature, no cavitation phenomenon, and no energy loss. .

Further, according to the second feature of the present invention, in addition to the above-mentioned effects, the proportional control valve controls the hydraulic system pressure at a speed proportional to the vehicle speed, thereby ensuring steering responsive to the vehicle speed.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a block diagram of the hydraulic system, Fig. 2 is a schematic plan view of the power steering, Fig. 3 is a side view of the tractor, and Fig. 4 is a sectional view of a part of the gear shift lever. , Fig. 5 is a conceptual diagram of the tractor transmission, Fig. 6 and Fig. 7 are block diagrams showing the control system of the solenoid (switching valve), Fig. 8 is an explanatory diagram of duty control, and Fig. 9 is a diagram showing the control system of the solenoid (switching valve). FIG. 2 is a configuration diagram of a hydraulic system illustrating an example. 13--controller, 34--detector, 38-hydraulic pump, 41--flow control valve, 46--duty control valve, 46A-proportional control valve. Patent applicant Kubota Iron Works Co., Ltd.

Claims (2)

[Claims] (1) In a power steering hydraulic system (40) consisting of a hydraulic pump (38), a flow control valve with an overload relief valve (41), and a controller (13), the flow control valve (41) and the controller (13) Between,
A control valve (46) whose duty is controlled is provided, and a speed detector (34) is provided to detect the speed state of the vehicle, and when the speed detector (34) detects a high speed state, the duty control valve (41) is provided. 1.) A power steering device for a vehicle, characterized in that a control means is provided to control a controller (13) to turn on/off hydraulic pressure to a controller (13). (2) In a power steering hydraulic system (40) consisting of a hydraulic pump (38), a flow control valve with overload relief valve (41), and a controller (13), the flow control valve (41) and the controller (13) Between,
A proportional control valve (46A) that is proportionally controlled is provided, a speed detector (34) is provided to detect the speed state of the vehicle, and when the speed detector (34) detects a high speed state, A power steering device for a vehicle, characterized in that a control means is provided for proportionally controlling the hydraulic pressure to the controller (13) by controlling the proportional control valve (46A).