JPH1111338A - Power steering device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] The effect of a volume chamber connected to a pipe via a throttle in order to prevent resonance or abnormal noise due to pulsation or vibration can be obtained equally in each pipe without increasing costs. Thus, an improved power steering device is provided. SOLUTION: In response to a steering load, one pipe 2a (2
b) is provided with a control valve 1 for simultaneously increasing the pressure of the other pipe 2b (2a) and increasing the pressure of the other pipe 2b (2a).
In a power steering apparatus having a power cylinder 5 for supplying pressure from a pressure chamber b through a volume chamber 8 having a throttle 7 and assisting a steering operation by a pressure difference, both pipes 2a and 2b have the same length. A volume chamber 8 is provided via a throttle 7 in each of the pipes 2a and 2b so that the pipe lengths are equal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a power steering control valve for increasing the pressure of one of the pipes and lowering the pressure of the other pipe in response to a steering load, and the pressure from both the pipes has a throttle. The present invention relates to a power steering device having a power cylinder supplied through a chamber and power assisting a steering operation by a pressure difference.

[0002]

2. Description of the Related Art A conventional power steering apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-8743 shown in FIG. In FIG. 7, pipes 2a and 2b from the control valve 1 are connected to cylinder chambers S1 and S2 of the power cylinder 5, respectively.
A volume chamber 8 in which a movable mass 17 is provided, and throttles 7a and 7
b is provided. Reference numeral 32 denotes a rack for steering wheels. The rack 32 constitutes a pinion (not shown) integral with the shaft 33, a steering gear, and integrally includes a piston 51. Reference numeral 4 denotes a steering gear case.

[0003] When a driver operates a steering wheel (not shown), a pinion rotates together with a shaft 33, and this rotation is converted into a linear motion required for the rack 32 to steer wheels. In the power steering apparatus, simultaneously, the control valve 1 responds to the steering load to increase the pressure of one of the pipes 2a (2b) and simultaneously reduce the pressure of the other pipe 2b (2a).
A pressure difference is generated between the
Energize. As a result, the steering operation force is reduced, and light and quick wheel steering becomes possible.

However, such a power steering apparatus has a disadvantage that pulsation and vibration are generated in the pressure supply system of the power cylinder because the power cylinder assists the steering operation with the power cylinder. Therefore, in order to eliminate pulsation and vibration generated in the pressure supply system of the power cylinder, a movable mass 17 is provided in the volume chamber 8 connected to the pipes 2a and 2b via the throttles 7a and 7b.

However, in such a device,
Although the volume chamber 8 is provided in each of the pipes 2a and 2b,
Since the pipes 2a and 2b are not the same length and the pipe lengths are different,
The effect of providing the volume chamber 8 having the throttles 7a and 7b causes a difference in each pipe, and the steering wheel and its peripheral parts may resonate or generate abnormal noise.

In the conventional apparatus, the movable mass 1 is
In the case of the vibration mode, the piping connected to the power cylinder 5 may vibrate in some vibration mode. Furthermore, in order to obtain the optimum movable mass 17, it is necessary to calculate a special solution according to the characteristics of the power cylinder 5 and each vehicle type. As a result, the cost increases as a whole.

[0007]

SUMMARY OF THE INVENTION The problem to be solved by the present invention has been made in view of the above facts, and a volume chamber connected to a pipe via a throttle to prevent resonance or abnormal noise due to pulsation or vibration. It is an object of the present invention to provide a power steering device improved so that the same effect can be obtained with each pipe without increasing the cost.

[0008]

SUMMARY OF THE INVENTION In order to solve this problem, a power steering apparatus according to a first aspect of the present invention is configured such that one pipe is set to a high pressure in response to a steering load and the other pipe is set to a low pressure. A power steering device having a power steering control valve, and a pressure cylinder from which pressure from both the pipes is supplied through a volume chamber having a throttle to power-assist steering operation by a pressure difference between the two pipes. Isometric,
A volume chamber is provided in each of the pipes via a throttle so that each pipe length is equal.

According to a second aspect of the present invention, in the power steering apparatus according to the first aspect, a block body is formed by accommodating the volume chambers having throttles provided in the respective pipes in the same case. It is characterized by the following.

Further, in the power steering apparatus according to a third aspect of the present invention, in the second aspect, the block body is connected to a power cylinder via an elastic member.

[0011]

As a result, in the power steering apparatus according to the first aspect of the present invention, each of the pipes is made equal in length, and each of the pipes is provided with a throttle via a throttle so that each pipe has the same length. Is provided, resonance and abnormal noise due to pulsation and vibration generated in the pressure supply system of the power cylinder can be prevented, and such effects can be obtained equally in each pipe. In addition, because there is no need for a movable mass due to the structure, there is no need to calculate a special solution that matches the characteristics of the vehicle type and the power cylinder in order to obtain the optimal movable mass, which is effective in reducing overall costs. is there.

According to a second aspect of the present invention, in the power steering apparatus according to the first aspect, the block chamber is formed by accommodating the volume chambers having the throttles provided in the respective pipes in the same case. Therefore, this block body has versatility, and is easy to position with respect to each pipe.

Further, in the power steering apparatus according to claim 3 of the present invention, since the block body is connected to a power cylinder via an elastic member in claim 2, the mass of the block body serves as a dynamic damper. It works and is effective not only to prevent pulsation and vibration due to the pressure medium, but also to prevent mechanical vibration.

[0014]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a front view showing a power steering device according to the present invention. Reference numeral 1 denotes a control valve connected to an oil pump and a reservoir tank (both not shown), and in response to a steering load, raises one pipe 2a (2b) to high pressure and simultaneously sets the other pipe 2b (2a). To lower the pressure. These pipes 2a, 2b are of equal length,
A block 3 to be described later is provided in the middle of 2b so that the respective pipes have the same length.

Reference numeral 4 denotes a gear case containing a steering gear composed of a pinion (not shown) and a rack 32. The rotation of a steering wheel (not shown) is input to the pinion integrated with the shaft 33, and this rotation is performed. Is converted into a linear motion of the rack 32 to steer the wheels. Reference numeral 5 denotes a power cylinder for power assisting the steering operation of the driver, and pipes 2a and 2b are respectively provided in cylinder chambers S1 and S2 of the power cylinder 5 (FIG. 7).
Connection). Note that the piston 51 of the power cylinder 5 is integrally connected to the rack 32 constituting the steering gear (see FIG. 7).

FIG. 2 is an external view of the block 3 interposed between the pipes 2a (2b). The body 3a of the block 3 is provided with hydraulic ports P1 to P4. The hydraulic port P1 communicates with the hydraulic port P3, and the hydraulic port P2 communicates with the hydraulic port P4. Between the control valve 1 and the power cylinder 5, the pipe 2a (2b) on the control valve 1 side is connected to the hydraulic port P1 (P2), and the pipe 2a (2b) on the power cylinder 5 side is connected to the hydraulic port P3.
(P4).

FIG. 3 is a sectional view for explaining the inside of the block body 3. As shown in FIG. FIG. 5A shows the hydraulic ports P1, P3
The hydraulic ports P2 and P4 have the same structure. FIG. 2B is a diagram showing a cross section taken along line AA of FIG.

As shown in the figure, the hydraulic port P1 (P2)
In the passage 6 that connects the hydraulic port P3 (P4) with the hydraulic port P3,
The oil volume chamber 8 is connected via a throttle element 70 having a throttle 7 with a hole diameter d. The oil volume chamber 8 is a cylindrical space in which a thread portion is formed, and is formed by screwing the throttle element 70 to the passage 6 side and then screwing the end cap 10 through the O-ring 9. The aperture element 70 can be exchanged for one having a different hole diameter d of the aperture 7, and its shape may be an orifice or a choke. Further, the volume of the oil volume chamber 8 is changed by replacing the end cap 10 with the dimension L of the end cap 10.
Can be set by changing.

An outward projection 10P is formed on the end cap 10. An inner cylinder 11, a rubber bush 12, and an outer cylinder 13 are attached to the projection 10P in this order from the inside, and a bracket 14 is inserted through these. Attach. The bracket 14 is for attaching the block body 3 to the power cylinder 5. However, the bracket 14
It is not a necessary member in the present invention. Reference numeral 15 denotes a nut for positioning the bracket 14 on the protrusion 10P.

Here, the basic operation of the power steering device will be described. First, when the driver operates a steering wheel (not shown), the pinion rotates together with the shaft 33, and this rotation is converted into linear motion required for the rack 32 to steer wheels. Thus, wheel steering according to the rotation of the steering wheel is performed. In the power steering device, the control valve 1 simultaneously increases the pressure of one of the pipes 2a (2b) in response to the steering load and lowers the pressure of the other pipe 2a (2b). Then, a pressure difference is generated between the cylinder chambers S1 and S2 of the power cylinder 5, and the rack 32 is urged by the piston 51 of the power cylinder 5. As a result, the steering operation force is reduced, and light and quick wheel steering becomes possible.

However, pulsation and vibration may occur in the hydraulic system of the power cylinder 5 due to the power assist of the steering operation by the power cylinder 5. Therefore,
In the device according to the present invention, a pipe in which an oil volume chamber 8 is disposed via a throttle 7 is used as a pipe for connecting the control valve 1 and the power cylinder 5.

FIG. 4 shows the gain (dB) corresponding to each frequency (Hz). The solid line A indicates the case where the control valve 1 and the power cylinder 5 are connected only by the pipe 2a (2b). A case where the oil volume chamber 8 is disposed in the pipe 2a (2b) via the throttle 7 is indicated by a broken line B. As is apparent from this figure, when the oil volume chamber 8 is disposed in the pipe 2a (2b) via the throttle 7, the gain (dB) in a specific frequency range is higher than when the oil volume chamber 8 is connected only by the pipe 2a (2b). It can be seen that has decreased.

However, even when the oil volume chamber 8 is provided via the throttle 7, if the pipes 2a and 2b are not the same length but the pipe lengths are different, the effect of the provision of the throttle 7 and the oil volume chamber 8 can be reduced. A difference appears for each pipe, and the steering wheel and its peripheral parts resonate and generate abnormal noise. For this reason, in the apparatus according to the present invention, the pipes 2a, 2b are made equal in length, and the pipes 2a, 2b are set to be equal in length.
b. An oil volume chamber 8 is provided via a throttle 7 for each.

According to such a configuration, resonance and abnormal noise due to pulsation and vibration generated in the pressure supply system of the power cylinder 5 are prevented, and such effects can be obtained equally in the respective pipes 2a and 2b. In addition, since the movable mass used in the related art becomes unnecessary, it is not necessary to calculate a special solution according to the type of the vehicle and the characteristics of the power cylinder 5 in order to obtain an optimal movable mass. It is effective for

FIG. 5 is a sectional view conceptually showing the inside of the block 3. As shown in FIG.
Inside the hydraulic port P1 (P2) and the hydraulic port P3
(P4) are connected to each other by passages 6, and at a position branched from the passages 6 through an orifice 7 through an oil volume chamber 8
Is arranged.

As shown in FIG. 5, in this embodiment, as a method of disposing an oil volume chamber in a pipe via a restrictor, an oil volume chamber 8 is disposed via a restrictor 7 at a position branched from the passage 6. However, the problem of abnormal noise occurs when the driver performs the steering operation to the full level and then suddenly switches back, that is, when the oil volume chamber 8 is filled with oil. Therefore, even if the connection is made as shown in FIG. 5, the effect of preventing abnormal noise can be sufficiently obtained.

Incidentally, the method of connecting the oil volume chamber via the throttle is similar to that of the prior art shown in FIG.
May be interposed between the passages 6 so that the oil always passes through the throttles 7a and 7b and the oil volume chamber 8.

Further, the apparatus according to the present invention comprises the pipes 2a, 2b
Are equal in length, and the pipes 2 are
It is not always necessary to form a block as long as the oil volume chamber 8 is disposed via the throttle 7 in each of the a and 2b. Thus, as in the present embodiment, the aperture element 70
If the block 3 is formed by storing each of the oil volume chambers 8 having the (throttle 7) in the main body 3a, which is the same case, the block 3 has versatility, and can be easily positioned with respect to the pipes 2a and 2b. is there.

FIG. 6 is a conceptual diagram showing a second embodiment of the present invention. The basic structure and operation of this embodiment are the same as those of the first embodiment, but instead of connecting the block body 3 to the power cylinder 5 via the bracket 14, the block body 3 is connected to a spring 16 which is an elastic member. Through the power cylinder 5. According to this configuration, the mass of the block body 3 acts as a dynamic damper, which is effective not only for preventing pulsation and vibration due to the pressure medium, but also for preventing mechanical vibration.

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment of a power steering device of the present invention.

FIG. 2 is an external view showing a block body in the same embodiment.

FIG. 3 is a cross-sectional view showing the block body in the same form from each direction.

FIG. 4 is a diagram comparing a case where a throttle and an oil volume chamber are combined with a pipe and a case where only a pipe is used with a gain (dB) corresponding to each frequency (Hz).

FIG. 5 is a conceptual diagram shown in a cross section for explaining a block body.

FIG. 6 is a front view showing a second embodiment of the power steering device of the present invention.

FIG. 7 is a sectional view of a main part showing a conventional power steering device.

[Explanation of symbols]

 Reference Signs List 1 control valve 2a, 2b piping 3 block body 3a main body 4 steering gear 5 power cylinder 6 passage 7 throttle 8 oil volume chamber 9 O-ring 10 end cap 11 inner cylinder 12 rubber bush 13 outer cylinder 14 bracket 15 nut 16 spring 17 movable mass 32 Rack 33 Shaft P1 to P4 Hydraulic port 70 Throttle element

Claims (3)

[Claims] 1. A power steering control valve for increasing the pressure of one of the pipes and lowering the pressure of the other pipe in response to a steering load, wherein the pressure from both the pipes is supplied through a volume chamber having a throttle. In a power steering apparatus having a power cylinder for power assisting a steering operation by the pressure difference, the two pipes are made equal in length, and a volume chamber is arranged via a throttle in each of the pipes so that each pipe length is equal. A power steering device, comprising: 2. The power steering apparatus according to claim 1, wherein said volume chamber having a throttle disposed in each of said pipes is housed in the same case to form a block body. 3. The method according to claim 2, wherein the block body is
A power steering device connected to a power cylinder via an elastic member.