JPH08318865A - Full hydraulic type power steering device - Google Patents

Abstract

PURPOSE: To make a power steering device in a small size, a light weight, and of a high reliability, by providing a drain slot to communicate either the first port or the second port to an exhaust port, by the relative movement of a housing and a spool, in the spool. CONSTITUTION: In the spool 8b of a steering correcting valve 8, a drain slot 8g1 or 8g2 to communicate the first port 8c or the second port 8d to an exhaust port 8e1 or 8e2, by the relative movement of a housing 8a and the spool 8b, is provided. As a result, when a deflection more than a specific amount of moving amount is generated between a steering device and a cylinder 7, the first port 8c or the second port 8d is comtmunicatecl to the exhaust port 8e1 or the exhaust port 8e2 through the drain slot 8g1 or 8g2, and the movement of a piston 7a is delayed until the relative movement amount of the housing 8a and the spool 8b is made less than a specific amount, and as a result, a slippage of the movement amount between the steering device and the cylinder 7 can be corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an all-hydraulic power steering system mainly applied to a vehicle steering system.

[0002]

2. Description of the Related Art Regarding the all-hydraulic power steering device, there is a known conventional technique described in Japanese Patent Publication No. 6-24949. The all-hydraulic power steering device disclosed in this document is provided with a moving amount detection sensor on the pistons of the steering device and the steering cylinder, and the control device confirms that the deviation of the moving amount between the steering device and the steering cylinder becomes a predetermined value or more. Upon detection, the solenoid valve in the hydraulic circuit is actuated to communicate the high pressure side cylinder chamber with the reservoir, thereby correcting the amount of movement of the piston of the steering cylinder.

As described above, the above-mentioned prior art requires a detection sensor, a control device, a solenoid valve and the like to correct the amount of movement of the piston of the steering cylinder, and there are many problems in terms of cost. Further, since it has a complicated electric circuit, many fail-safe means are required to ensure reliability.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a low cost and highly reliable all-hydraulic power steering system.

[0005]

In order to solve the above problems, the first aspect of the present invention includes a first hydraulic chamber and a second hydraulic chamber which are partitioned from each other by a piston connected to the steered wheels. A cylinder and a reservoir that stores hydraulic fluid,
A hydraulic pressure source that sucks and discharges the hydraulic fluid stored in the reservoir, a hydraulic pressure path that connects the hydraulic pressure source and the reservoir to the cylinder, and a steering device that is disposed in the hydraulic pressure path. And a switching valve for selectively connecting the first hydraulic chamber and the second hydraulic chamber to either the hydraulic pressure source or the reservoir depending on the operating direction of the steering device. Type power steering device, which is connected to a piston of the cylinder and one side of the steering device to move by an amount corresponding to a movement amount or an operation amount of the piston and the steering device, and at the same time a first liquid of the cylinder. A housing having first and second ports respectively communicating with the pressure chamber and the second hydraulic chamber, and a discharge port communicating with the reservoir; Steering correction including a spool that is movably installed in a housing and that is connected to the piston of the cylinder and the other side of the steering device and that moves by an amount corresponding to a movement amount or an operation amount of the piston and the steering device. A valve is provided, and the spool is provided with a drain slot that allows one of the first port and the second port to communicate with the discharge port by relative movement of the housing and the spool. It is a hydraulic power steering device.

According to a second aspect of the present invention, at least one of the first port and the second port is provided with an orifice, and the full hydraulic power steering system according to the first aspect is satisfied. The device.

[0007]

According to the all-hydraulic power steering apparatus according to the first aspect of the present invention, when the deviation of the movement amount of a predetermined amount or more occurs between the steering device and the cylinder, the first port or The movement of the piston of the cylinder is delayed until the relative movement of the housing of the steering correction valve and the spool is equal to or less than a predetermined amount by communicating the second port with the discharge port. Therefore, the movement amount between the steering device and the cylinder is deviated. Can be corrected.

According to the all-hydraulic power steering device of the second aspect, since at least one of the first port and the second port has an orifice, the steering device and the cylinder are connected. The steered wheels do not suddenly operate when the deviation of the movement amount between them is corrected.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Only the features of the present invention will be described below with reference to the drawings.

FIG. 1 is a system diagram of an all-hydraulic power steering system according to the present invention. The steering wheel 1 is attached to a vehicle and is rotated when turning the vehicle. The steering wheel 1 is connected to a pinion gear 3 via a steering shaft 2. The pinion gear 3 meshes with a rack gear 4, and the rotational operation of the steering wheel 1 is converted into a linear movement of the rack gear 4 via the steering shaft 2 and the pinion gear 3.

Hydraulic oil is stored in the reservoir 5 and is always kept at atmospheric pressure. The hydraulic oil stored in the reservoir 5 is sucked by the hydraulic pump 6 which is a hydraulic pressure source, and then pressurized and discharged.

The steering cylinder 7 has pistons 7a connected at both ends to steering wheels of a vehicle (not shown).
A first hydraulic pressure chamber 7b and a second hydraulic pressure chamber 7c are formed by the above, and the piston 7a is moved by the introduction of operating hydraulic pressure into each hydraulic pressure chamber to steer the steered wheels of a vehicle (not shown).

The steering correction valve 8 is connected to the piston 7a of the steering cylinder 7 by a stay 9 and is movable integrally with the piston 7a, and a spool 8b is movably installed in the housing 8a. The spool 8b is connected to the rack gear 4 by a flexible wire 10 and moves by an amount according to the amount of movement of the rack gear 4. The steering correction valve 8 will be described in detail later.

The steering switching valve 11 is a two-position switching valve which is switched depending on the operating direction of the steering wheel 1, and is connected to the discharge port of the hydraulic pump 6 and the reservoir 5, the first hydraulic passage 12a and the second hydraulic pressure, respectively. The passages 12b communicate with each other. On the other hand, the hydraulic pressure chambers 7b and 7c of the cylinder 7 and the steering correction valve 8 are connected to the steering switching valve 11 by a third hydraulic pressure passage 12c and a fourth hydraulic pressure passage 12d. Further, the steering correction valve 8 is always in communication with the reservoir 5 by the discharge passage 13.

The steering switching valve 11 includes the first
A first position 11a connecting the hydraulic pressure passage 12a and the second hydraulic pressure passage 12b to the third hydraulic pressure passage 12c and the fourth hydraulic pressure passage 12d, respectively, and the first hydraulic pressure passage 12a and the second hydraulic pressure passage 12b. The fourth hydraulic pressure passage 12d and the third hydraulic pressure passage 1 respectively.
2c and the 2nd position 11b connected.

FIG. 2 shows the details of the steering correction valve 8 when the steering wheel 1 is in a non-operating (neutral) state. The housing 8a of the steering correction valve 8 is provided with a first port 8c communicating with the first hydraulic pressure chamber 7b of the cylinder 7 and a second port 8d communicating with the second hydraulic pressure chamber 7c. Two discharge ports 8e1 and 8e2 communicating with the reservoir 5 are provided. The first port 8c and the second port 8d are orifices 8c0, 8 for restricting the flow of hydraulic oil.
It has d0.

Two drain slots 8g1 and 8g2 are installed in the spool 8b which is installed in a spool hole 8f provided in the housing 8a so as to be movable relative to the housing 8a. In the above, each communicates with the first port 8c and the second port 8d. In addition, at both ends of the spool hole 8f, seal members 8h1 and 8h2 for blocking the inside of the spool hole 8f from the outside are provided.
Is installed.

In the state of FIG. 2, the steering switching valve 11 is set to the first position depending on the operating direction of the steering wheel 1.
Since it is located at the position 11a, the working hydraulic pressure generated by the hydraulic pump 6 is passed through the second hydraulic pressure passage 12c, the steering switching valve 11 and the first hydraulic pressure passage 12a to the first hydraulic pressure chamber 7b of the cylinder 7. , An amount corresponding to the operation amount of the steering wheel 1 is introduced. On the other hand, the second hydraulic chamber 7c communicates with the reservoir 5 via the fourth hydraulic passage 12d, the steering switching valve 11 and the second hydraulic passage 12b, and has the same pressure as the atmospheric pressure. There is. Therefore, the piston 7a of the cylinder 7 is pressed to the right in FIG. 2 by the operating hydraulic pressure in the first hydraulic chamber 7b, and is moved by an amount corresponding to the operation amount of the steering wheel 1. Here, the housing 8a of the steering correction valve 8 moves integrally with the piston 7a of the cylinder 7, and the spool 8b.
Also moves by an amount corresponding to the operation amount of the steering wheel 1, so that in an ideal state, the relative positional relationship between the housing 8a and the spool 8b does not always change due to the operation of the steering wheel 1.

However, when a part of the amount of hydraulic fluid introduced into the first hydraulic chamber 7b leaks to the second hydraulic chamber 7c side, the moving amount of the piston 7a corresponds to the operating amount of the steering wheel 1. Since the amount is less than the fixed amount, the amount of movement of the housing 8a is small with respect to the amount of movement of the spool 8b, and the housing 8a is located to the left of the spool 8b as shown in FIG. As a matter of course, in this state, a deviation also occurs between the steering wheel 1 and the movement amount of the steered wheels. By the relative movement between the spool 8b and the housing 8a,
Drain slot 8g2 of spool 8b and housing 8a
It overlaps the discharge port 8e2 of
The second hydraulic chamber 7c communicates with the discharge port 8e2 of the housing 8a via the second port 8d and the drain slot 8g2.

As shown in FIG. 4, when the driver subsequently returns the steering wheel 1 in the direction opposite to the above-mentioned operation, the steering switching valve 11 is moved to the first position 11a.
To the second position 11b. Therefore, the hydraulic pressure of the hydraulic pump 6 is applied to the cylinder 7 via the first hydraulic pressure passage 12a, the steering switching valve 11 and the fourth hydraulic pressure passage 12d.
Is introduced into the second hydraulic chamber 7c. On the other hand, the first hydraulic chamber 7b of the cylinder 7 is connected to the reservoir 5 via the third hydraulic passage 12c, the steering switching valve 11 and the second hydraulic passage 12b.

Here, the operating oil pressure introduced into the second hydraulic chamber 7c is the second port 8d of the housing 8a, the drain slot 8g2 of the spool 8b and the housing 8a.
Since it is discharged to the reservoir 5 by the amount limited by the orifice 8d0 via the discharge port 8e2, the piston 7a of the hydraulic cylinder 7 and the steering correction connected thereto by the working hydraulic pressure in the second hydraulic chamber 7c. The amount of movement of the housing 8a of the valve 8 is limited to an extremely small amount, and the spool 8b that is interlocked with the steering wheel 1 moves to the left in FIG. 4 with respect to the housing 8a. When the spool 8b moves to the left in FIG. 4 with respect to the housing 8a, the overlap amount S0 of the discharge port 8e2 and the drain slot 8g2 becomes 0,
Since the communication between the second hydraulic pressure chamber 7c and the reservoir 5 is cut off, the hydraulic oil in the second hydraulic pressure chamber 7c is no longer discharged to the reservoir 5, and the inside of the second hydraulic pressure chamber 7c The operating oil moves the piston 7a of the cylinder 7 to the left in FIG. 4 by an amount corresponding to the operation amount of the steering wheel 1, and thereafter the spool 8b and the housing 8a move integrally. As a result, the deviation between the steering wheel 1 and the piston 7a of the cylinder 7 and the steered wheels is corrected to only the steering angle θ0 corresponding to the distance S1 between the discharge port 8e2 and the drain slot 8g2 in FIG.

Therefore, when the steering wheel 1 is returned to the non-operating position, the deviation between the steering wheel 1 and the piston 7a of the cylinder 7 and the steered wheels is corrected only to the steering angle θ0 described above (FIG. 5). ).

The solid line in FIG. 5 is a characteristic diagram showing the relationship between the amount of rotation of the steering wheel 1 and the amount of movement of the cylinder piston 7a of the above-described full hydraulic power steering device. In FIG. 5, A corresponds to the state in which the steering wheel 1 and the piston 7a in FIG. 2 are in the neutral position, and B corresponds to the state in FIG. 3 or 4. As shown in FIG. 4, C in FIG. 5 indicates that after the hydraulic oil by the hydraulic pump 6 is introduced into the second hydraulic chamber 7c of the cylinder 7, the spool 8b is relatively left with respect to the housing 8a in FIG. This shows a state in which the overlap amount S0 of the drain slot 8g2 and the discharge port 8e2 has become 0 due to the movement toward one side. Here, the characteristics during the transition from the state B to the state C in FIG. 5 by the orifices 8c0 and 8d0 provided in the first port 8c and the second port 8d become a gentle curve as shown in the figure. Further, D in FIG. 5 corresponds to a state in which the steering wheel 1 is returned to the non-operating position in the all hydraulic power steering device according to the present invention. still,
In FIG. 5, the broken line represents the characteristic when the function of correcting the deviation between the steering wheel 1 and the cylinder piston 7a according to the present invention is not provided.

[0024]

As described above, according to the all-hydraulic power steering apparatus of the present invention, the deviation between the steering wheel and the steered wheels can be corrected only by adding the steering correction valve, so that the cost can be reduced. It can be a compact and lightweight all-hydraulic power steering device.

[Brief description of drawings]

FIG. 1 is a system diagram of an all-hydraulic power steering device of the present invention.

FIG. 2 is a detailed view of the essential parts of an all-hydraulic power steering system according to the present invention.

FIG. 3 is a detailed view of the essential parts of an all-hydraulic power steering device according to the present invention.

FIG. 4 is a detailed view of the essential parts of an all-hydraulic power steering device according to the present invention.

FIG. 5 is a characteristic diagram of an all-hydraulic power steering device of the present invention.

[Explanation of symbols]

1 Steering Wheel 5 Reservoir 6 Hydraulic Pump 7 Cylinder 7a Piston 7b First Hydraulic Chamber 7c Second Hydraulic Chamber 8 Steering Compensation Valve 8a Housing
8b Spool 8c 1st port 8d 2nd port 8e1, 8
e2 Discharge port 8g1, 8g2 Drain slot 11 Steering switching valve 12a, 12b, 12c, 12d Hydraulic path

Claims (2)

[Claims] 1. A cylinder including a first hydraulic chamber and a second hydraulic chamber, which are partitioned from each other by a piston connected to a steering wheel, a reservoir storing a hydraulic fluid, and a hydraulic fluid stored in the reservoir. A hydraulic pressure source that sucks and discharges the liquid, a hydraulic pressure path that connects the hydraulic pressure source and the reservoir to the cylinder, and a hydraulic pressure path that is disposed in the hydraulic pressure path and that is connected to a steering device. A full-hydraulic power steering device comprising: a switching valve that selectively communicates each of the first hydraulic chamber and the second hydraulic chamber with either the hydraulic pressure source or the reservoir depending on the operating direction. The piston and one side of the steering device to move by an amount corresponding to a movement amount or an operation amount of the piston and the steering device, and A housing having a first port and a second port respectively communicating with the first hydraulic chamber and the second hydraulic chamber of the vehicle, and a discharge port communicating with the reservoir,
Steering including a spool that is movably installed in the housing and that is connected to a piston of the cylinder and the other side of the steering device and that moves by an amount corresponding to a movement amount or an operation amount of the piston and the steering device. A compensation valve is provided, and the first spool is provided on the spool by relative movement of the housing and the spool.
An all-hydraulic power steering system comprising a drain slot for communicating either the port or the second port with the discharge port. 2. The first port and the second port,
2. An all-hydraulic power steering system according to claim 1, wherein at least one of them has an orifice.