JP3073601B2 - Hydraulic control device for hydraulic power steering - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control system for a hydraulic power steering system used in vehicles such as automobiles.

[0002]

2. Description of the Related Art As one of hydraulic control devices for a hydraulic power steering system, Japanese Patent Application Laid-Open No. 63-166658 discloses a hydraulic control system having four flow paths respectively connecting a hydraulic supply source, oil chambers of a power cylinder, and a reservoir. Bridge circuit
A main control which is provided with a variable throttle provided in each flow path of the bridge circuit and operates according to the steering torque, and throttle-controls the hydraulic oil supplied to the power cylinder according to the steering torque in all vehicle speed ranges. A bypass circuit composed of two flow paths respectively connecting the oil chamber and the reservoir of the device and the power cylinder; a high-speed variable throttle provided in each flow path of the bypass circuit and operating according to a steering torque; An electromagnetic variable throttle valve is provided in each of the flow paths of the bypass circuit and is closed when the vehicle speed is lower than a set vehicle speed and the opening area increases in accordance with the vehicle speed when the vehicle speed is equal to or higher than the set vehicle speed. There has been proposed a device provided with a high-speed control device that throttle-controls hydraulic oil supplied to a power cylinder in accordance with torque.

[0003]

In the hydraulic control apparatus disclosed in the above publication, an electromagnetic variable throttle valve is provided in each flow path of the bypass circuit, one of which functions when steering left and the other when steering right. Since the electromagnetic variable throttle valve is required to have the same characteristics in each case, the same characteristics are required in view of the processing accuracy (consisting of multiple components and accumulating errors). There is a possibility that the characteristics may differ between left and right steering without being obtained. The present invention has been made to address the above-described problem, and an object of the present invention is to improve the steering feeling by reducing the difference between left and right steering characteristics.

[0004]

In order to achieve the above-mentioned object, according to the present invention, the hydraulic control device includes a hydraulic supply source, four oil chambers of a power cylinder, and four flow paths respectively connecting a reservoir. And a variable throttle provided in each flow path of the bridge circuit and operated in accordance with the steering torque, and supplies hydraulic oil supplied to the power cylinder in accordance with the steering torque in all vehicle speed regions. A main control device for controlling the throttle, a bypass circuit composed of two flow paths which respectively connect the two oil chambers of the power cylinder and the reservoir and partially overlap each other, and are provided in each flow path of the bypass circuit according to the steering torque. A variable throttle for high-speed operation, which is provided in each of the flow paths upstream of the overlapping portion of the bypass circuit, and is lowered from the high-pressure side oil chamber when the power cylinder is operated by steering. A switching valve for preventing the flow of hydraulic oil to the side oil chamber, and a single electromagnetic variable throttle provided at the overlapping portion of the bypass circuit and closed when the vehicle speed is lower than the set vehicle speed and the opening area increases according to the vehicle speed when the vehicle speed is higher than the set vehicle speed. A high-speed control device that is constituted by a valve and throttle-controls the hydraulic oil supplied to the power cylinder according to the vehicle speed and the steering torque in a high-speed vehicle speed region equal to or higher than the set vehicle speed is provided.

[0005]

In the hydraulic control apparatus according to the present invention, the flow of hydraulic oil from the high-pressure side oil chamber to the low-pressure side oil chamber when the power cylinder is operated by steering to each flow path upstream of the overlap portion of the bypass circuit. A single electromagnetic variable throttle valve is provided at the overlap portion of the bypass circuit, and a single electromagnetic variable throttle valve is provided at the overlap portion of the bypass circuit. Although the hydraulic oil flows through the electromagnetic variable throttle valve, the flow of hydraulic oil from the high pressure side oil chamber to the low pressure side oil chamber of the power cylinder is blocked by the other switching valve, and a bypass circuit is passed through the other switching valve during left steering. Hydraulic oil flows through the electromagnetic variable throttle valve provided at the overlapping part, but the flow of hydraulic oil from the high pressure side oil chamber to the low pressure side oil chamber of the power cylinder is blocked by one of the switching valves It is. Therefore, at the time of right steering and at the time of left steering, hydraulic oil flows to the same electromagnetic variable throttle valve to obtain the same characteristics, and there is no characteristic difference between the electromagnetic variable throttle valves. As a result, the steering feeling can be improved.

[0006]

An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show a hydraulic power steering device for a vehicle. The power steering device includes a pump (hydraulic supply source) 10 driven by an engine (not shown) and a reservoir 20 and a steering wheel 31. Pump 1 that operates according to the rotation of
0, a rotary control valve 30 for restricting the hydraulic oil supplied to a well-known power cylinder 40 (power assisting the steering operation), and a hydraulic oil supplied to the power cylinder 40 in cooperation with the control valve 30. An electromagnetic variable throttle valve 50 for controlling the throttle is provided.

The control valve 30 includes a steering wheel 31
And a steering linkage (not shown) coaxially arranged on the outer periphery and power-assisted by a power cylinder 40. A valve body 33 (expanded and shown in FIG. 2) is connected to the valve shaft 32 and the valve body 33 at each end. A well-known torsion bar (not shown) for causing relative rotation between the valve shaft 33 and a valve housing (not shown) for accommodating them is provided between the valve shaft 32 and the valve body 33.
The control unit A, the control unit B, and the control unit C are each 1 in the circumferential direction.
They are formed at intervals of 80 degrees.

The control section A includes a bridge circuit Pa composed of four flow paths P1, P2, P3, and P4 connecting the oil chambers 40L and 40R of the pump 10 and the power cylinder 40 and the reservoir 20, respectively. The main control device, which is constituted by variable throttles 1R, 1L, 2L, and 2R provided in each flow path, controls throttle of hydraulic oil supplied to the power cylinder 40 in accordance with steering torque in all vehicle speed ranges. The opening area S1 formed by each of the variable throttles of the control unit A is represented by a solid line in FIG. 3 according to the relative rotation angle (corresponding to the steering torque) between the valve shaft 32 and the valve body 33. Changes to

The control unit B is connected in parallel to the passage P3 of the bridge circuit Pa, and is connected to the oil chamber 40L of the power cylinder 40.
And a reservoir P20, and a high-speed variable throttle 3L (closed later than the variable throttles 1L and 2L) and a switching valve 4L provided in the channel P5.
The opening area S2 formed by the high-speed variable stop 3L changes as shown by a broken line in FIG. 3 according to the relative rotation angle between the valve shaft 32 and the valve body 33. On the other hand, the control unit C is connected in parallel to the passage P4 of the bridge circuit Pa, and is connected to the oil chamber 40R of the power cylinder 40 and the reservoir 20R.
And a high-speed variable throttle 3R provided in the flow channel P6 (closed later than the variable throttles 1R and 2R).
The opening area formed by the high-speed variable stop 3R is the same as the opening area S2 formed by the high-speed variable stop 3L of the control section C, and the valve shaft 32 and the valve body are formed. It changes as shown by the broken line in FIG.
The high-speed variable throttles 3L and 3R throttle the flow paths P5 and P6 in accordance with the steering torque.
4R moves from the high pressure side oil chamber 40R or 40L to the low pressure side oil chamber 40L or 4L when the power cylinder 40 is operated by steering.
This prevents the flow of hydraulic oil to the OR. The flow paths P5 and P6 constitute a bypass circuit Pb.
A single electromagnetic variable throttle valve 50 is provided downstream of the overlapping portion Pb1 of the bypass circuit Pb, that is, downstream of the switching valves 4L and 4R.

As shown in FIG. 1, the energization of the electromagnetic variable throttle valve 50 is controlled by a computer 60 based on a signal from a vehicle speed sensor 61. When the vehicle speed is higher than the set vehicle speed when the vehicle is closed, the opening area is set to gradually increase as the vehicle speed increases. The electromagnetic variable throttle valve 50 includes the bypass circuit Pb, the high-speed variable throttles 3L and 3R, and the switching valves 4L and 4L.
R constitutes a high-speed control device for restricting the hydraulic oil supplied to the power cylinder 40 in the high-speed vehicle speed region equal to or higher than the set vehicle speed in cooperation with the main control device described above.

In the embodiment constructed as described above, when the steering wheel 31 is operated to rotate and the valve shaft 32 rotates to the right in FIG. Both variable diaphragms 1R,
2R and the high-speed variable aperture 3R of the control unit C can obtain the aperture operation, respectively, and the variable apertures 1L, 1L,
The opening operation is obtained by the high-speed variable throttle 3L of the control unit B and the closing operation by the switching valve 4L of the control unit B, and the opening operation is obtained by the switching valve 4R of the control unit C. . On the other hand, when the rotational movement is performed in the opposite direction, the diaphragm operation is obtained by both the variable diaphragms 1L and 2L of the control unit A and the high-speed variable diaphragm 3L of the control unit B, respectively. , 2R and the high-speed variable throttle 3R of the control unit C can obtain the opening operation, the switching valve 4L of the control unit B can obtain the opening operation, and the switching valve 4R of the control unit C can obtain the closing operation. Can be

By the way, in a vehicle speed region below the set vehicle speed where the electromagnetic variable throttle valve 50 is fully closed, the steering wheel 31 is operated to rotate, and the valve shaft 32 rotates rightward with respect to the valve body 33 in FIG. When moved, the hydraulic oil discharged from the pump 10
The oil is guided to the right oil chamber 40R of the power cylinder 40 through the variable throttle 1L opened by being throttled by R and 2R, and the hydraulic oil in the left oil chamber 40L flows to the reservoir 20 through the opened variable throttle 2L. In this case, the control unit B
Is closed, the hydraulic oil does not flow from the high pressure side oil chamber 40R of the power cylinder 40 to the low pressure side oil chamber 40L through the bypass circuit Pb. Therefore, in this case, the relationship between the relative rotation angle between the valve shaft 32 and the valve body 33 and the hydraulic pressure supplied to the power cylinder 40 changes as shown by the solid line in FIG.

In the vehicle speed range above the set vehicle speed, the electromagnetic variable throttle valve 50 opens according to the vehicle speed. Therefore, in addition to the above-described operation, the high-speed variable throttle 3L and the switching valve 4L of the flow path P6 and the electromagnetic variable throttle valve 50 As a result, the relationship between the relative rotation angle of the valve shaft 32 and the valve body 33 and the hydraulic pressure supplied to the power cylinder 40 corresponds to the vehicle speed as shown in FIG. Change. That is, in a vehicle speed region equal to or higher than the set vehicle speed, the opening area of the electromagnetic variable throttle valve 50 sequentially increases as the vehicle speed increases.
The solid characteristic line (characteristic line when the opening area of the electromagnetic variable throttle valve 50 is zero) and the broken line (characteristic line when the opening area of the electromagnetic variable throttle valve 50 is maximum) shown in FIG.
The characteristic line changes depending on the vehicle speed.

When the steering wheel 31 is rotated and the valve shaft 32 is rotated leftward in FIG. 2 with respect to the valve body 33, the same operation as described above is obtained and the same characteristics are obtained. Is obtained.

In the above embodiment, the control section A and the control sections B and C are provided on the same circumference, and the control valve 30 is configured to have a short axial dimension. However, as shown in FIG. Part A
And the control units B and C are displaced in the axial direction and are configured in two stages, and the circumferential interval between the control units A, B, and C is set to 120 degrees.
The axial grooves formed in the valve body 33 are inserted into the flow paths P5 and P5.
6 has the advantage that the number of piping connection ports provided in the control valve 30 can be reduced. In the above embodiment, the valve shaft 32 and the valve body 3
The switching valves 4L and 4R configured by 3 are switching valves that prevent the flow of hydraulic oil from the high-pressure oil chamber to the low-pressure oil chamber when the power cylinder 40 is operated by steering. As shown, the check valves V permit the flow to the electromagnetic variable throttle valve 50 in each of the flow paths P5 and P6 and prevent the backflow.
It is also possible to implement this as the above-mentioned switching valve by interposing 1, V2.

In the above embodiment, the high-speed variable stop 3
Although the example in which L and 3R are provided upstream of the switching valves 4L and 4R has been described, as shown in FIGS. 6 and 7, the high-speed variable throttles 3L and 3R are connected to a polymerization portion downstream of the switching valves 4L and 4R. It is also possible to implement the present invention by providing it in series with Pb1, and in this case, it is also possible to arrange an electromagnetic variable throttle valve 50 upstream of these high-speed variable throttles 3L and 3R as shown in FIG. It is. Also, in this case, instead of the high-speed variable throttles 3L and 3R provided in series, as shown in FIGS. 9 and 10, the high-speed variable throttles 3L1, 3R1, 3L2 provided respectively in the bridge circuit and each flow path thereof. 3R
2, it is also possible to implement.

In the above embodiment, the high-speed variable throttles 3L and 3R are arranged in parallel with the variable throttles 2L and 2R provided in the flow paths P3 and P4 of the bridge circuit Pa. As shown in FIGS. 11 and 12, the bypass circuit Pb is provided with a portion that also serves as the bridge circuit Pa, so that each of the high-speed variable diaphragms 3L and 3R is replaced with each of the variable diaphragms 2L and
It is also possible to carry out the embodiment so that the 2Rs are arranged in series.

In short, in each of the above embodiments,
Each flow path P upstream of the overlapping portion Pb1 of the bypass circuit Pb
5, P6, are provided with switching valves 4L and 4R for preventing the flow of hydraulic oil from the high pressure side oil chamber to the low pressure side oil chamber when the power cylinder 40 is operated by steering, and a bypass circuit Pb.
A single electromagnetic variable throttle valve 50 is provided at the overlapping portion Pb1, the switching valve 4L is closed and the switching valve 4R is opened and the switching valve 4R is opened at the time of right steering in a high-speed vehicle speed region equal to or higher than the set vehicle speed, and the high-speed variable throttle 3R and the switching valve are opened. Electromagnetic variable throttle valve 50 through 4R
Although the operating oil flows through the switching valve 4L, the flow of the operating oil from the high pressure side oil chamber 40R of the power cylinder 40 to the low pressure side oil chamber 40L is blocked by the switching valve 4L.
When R closes and the switching valve 4L opens, hydraulic oil flows to the electromagnetic variable throttle valve 50 through the high-speed variable throttle 3L and the switching valve 4L, but the switching valve 4R causes the low-pressure side oil to move from the high-pressure side oil chamber 40L of the power cylinder 40 to the low-pressure side oil. The flow of the hydraulic oil to the chamber 40R is blocked. Therefore, the hydraulic oil flows to the same electromagnetic variable throttle valve 50 at the time of right steering and left steering to obtain the same characteristics, and no characteristic difference occurs at the electromagnetic variable throttle valve 50. And the steering feeling can be improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a view showing a developed configuration of FIG. 1 using a valve shaft and a valve body.

FIG. 3 is a graph showing a relationship between a relative rotation angle between a valve shaft and a valve body and an opening area of each variable throttle.

FIG. 4 is a graph showing a relationship between a relative rotation angle and a hydraulic pressure using a vehicle speed as a parameter.

FIG. 5 is a diagram showing a modification of FIG. 2;

FIG. 6 is an overall configuration diagram showing an example in which a high-speed variable throttle is provided in series at a polymerization portion downstream of a switching valve.

FIG. 7 is a view showing the developed configuration of FIG. 6 using a valve shaft and a valve body.

FIG. 8 is a diagram showing an example in which an electromagnetic variable throttle valve is arranged upstream of the high-speed variable throttle in FIG. 6;

FIG. 9 is a diagram showing a modification of FIG. 6;

FIG. 10 is a diagram showing a modification of FIG. 8;

FIG. 11 is an overall configuration diagram showing an example in which a portion of the bypass circuit that also serves as a bridge circuit is increased, and a high-speed variable diaphragm is arranged in the same portion.

FIG. 12 is a view showing the developed configuration of FIG. 11 using a valve shaft and a valve body.

[Explanation of symbols]

10 pump (hydraulic supply), 20 reservoir, 30
Control valve, 31: Steering wheel, 32: Valve shaft, 33: Valve body, Pa: Bridge circuit, P
b: bypass circuit, Pb1: polymerization site, P1 to P6: flow path, 1R, 1L, 2R, 2L: variable throttle, 3R, 3L ...
High-speed variable throttles, 4R, 4L: switching valve, 40: power cylinder, 40R, 40L: oil chamber, 50: electromagnetic variable throttle valve.

──────────────────────────────────────────────────続 き Continued on the front page (72) Kyosuke Haga 1-1-1, Asahi-cho, Kariya-shi, Aichi Prefecture Inside Toyota Koki Co., Ltd. (72) Mikio Suzuki 1-1-1, Asahi-cho, Kariya-shi, Aichi Toyota Koki (56) References JP-A-63-166658 (JP, A) JP-A-2-306687 (JP, A) JP-A-63-166659 (JP, A) JP-A-63-166661 (JP, A) A) JP-A-63-87370 (JP, A) JP-A-3-8976 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B62D 6/00-6/04 B62D 5 / 083

Claims (1)

(57) [Claims] 1. A bridge circuit comprising four flow paths respectively connecting a hydraulic supply source, both oil chambers of a power cylinder, and a reservoir, and a variable circuit provided in each flow path of the bridge circuit and operated according to a steering torque. Composed by an aperture,
A main controller that throttles and controls the hydraulic oil supplied to the power cylinder in accordance with the steering torque in all vehicle speed ranges, and two flow passages that connect both oil chambers of the power cylinder and the reservoir and that partially overlap A bypass circuit, a high-speed variable throttle provided in each flow path of the bypass circuit and operated in accordance with a steering torque, and the power cylinder provided in each flow path upstream of the overlapping portion of the bypass circuit by steering. A switching valve for preventing the flow of hydraulic oil from the high-pressure side oil chamber to the low-pressure side oil chamber during operation; The hydraulic fluid supplied to the power cylinder is throttled in accordance with the vehicle speed and the steering torque in the high-speed vehicle speed range above the set vehicle speed. Hydraulic power steering hydraulic control apparatus provided with a high-speed control apparatus Gosuru.