JP3786525B2 - Hydraulic control valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic control valve that seals between a cylindrical housing and a valve member that is rotatably inserted into the housing by a seal ring.
[0002]
[Prior art]
This hydraulic control valve is used, for example, in a hydraulic power steering device of an automobile. A hole is formed in the housing of the hydraulic control valve, and a valve member that rotates relative to the steering operation is fitted in the hole. An annular oil chamber is formed between the outer peripheral surface of the valve member and the inner peripheral surface of the housing, and a seal ring for partitioning the annular oil chamber into a plurality of portions is provided. This seal ring seals adjacent portions of the annular oil chamber, and is fitted into an annular circumferential groove formed on the outer peripheral surface of the valve member.
[0003]
The circumferential groove is defined by a pair of opposing side surfaces and a groove bottom, and has a substantially rectangular cross-sectional shape. A rounded surface formed of a concave curved surface is formed at the corner of the groove bottom of the circumferential groove.
The cross section of the seal ring is substantially rectangular. The inner peripheral edge of the seal ring is chamfered, thereby removing the corners of the inner peripheral edge so that the inner peripheral edge does not rub against the above-described rounded surface.
[0004]
When the oil pressure in the annular oil chamber increases, the side surface of the seal ring is pressed against one side surface of the circumferential groove, and the outer peripheral surface of the seal ring is pressed against the inner peripheral surface of the hole of the housing. Is sealed. In this state, the seal ring is made of polytetrafluoroethylene (PTFE) in order to reduce friction when the valve member relatively rotates in the housing.
[0005]
[Problems to be solved by the invention]
However, PTFE is a material that is difficult to process, and in particular, since the chamfering of the inner peripheral edge takes time, the seal ring is expensive.
On the other hand, when the chamfering of the inner peripheral edge of the seal ring is omitted, the valve member and the housing rotate relative to each other as a result of the friction between the corner formed at the inner peripheral edge of the seal ring and the rounded surface formed at the corner of the peripheral groove. Sometimes friction increases.
[0006]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a hydraulic control valve that solves the technical problems described above and has low friction when the valve member is rotated in the housing and is inexpensive.
[0007]
[Means for Solving the Problems]
In order to achieve this object, a hydraulic control valve according to a first aspect of the present invention includes a cylindrical housing, a valve member that is rotatably inserted into the housing, and a periphery formed on the outer periphery of the valve member. A hydraulic control valve including a seal ring fitted in a groove, wherein the seal ring is pressed against the inner peripheral surface of the housing and one side surface of the peripheral groove by hydraulic pressure to seal between the housing and the valve member. At both corners of the groove bottom of the circumferential groove, there are provided a relief part consisting of a recess that avoids contact with the inner peripheral edge of the seal ring, and a rounded surface that connects the side of the relief part and the circumferential groove to each other, The boundary position between the side surface of the circumferential groove and the rounded surface at the corner of the groove bottom is inwardly in the radial direction of the valve member than the portion at the bottom of the groove and between the relief portions of both corners. The valve member is formed on both sides of the circumferential groove In the opposite direction, the width of the relief portion at each corner of the groove bottom is larger than the difference between the width of the seal ring and the width of the circumferential groove, and the seal ring is pressed against the inner peripheral surface of the housing by hydraulic pressure. In this case, there is an annular gap between the inner circumference of the seal ring and the portion of the groove bottom of the circumferential groove between the relief portions at both corners .
[0008]
According to this configuration, the corner of the circumferential groove and the inner peripheral edge of the seal ring do not rub against each other, so friction between the seal ring and the peripheral groove can be reduced, and chamfering of the inner peripheral edge can be omitted. .
Further, when the hydraulic pressure rises at low temperatures, the pressure oil is guided to the groove bottom of the circumferential groove through the escape portion, so that the outer peripheral surface of the seal ring is reliably pressed against the inner peripheral surface of the housing. Can be reliably sealed.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a hydraulic control valve according to an embodiment of the present invention will be described with reference to the accompanying drawings, taking a rack and pinion type hydraulic power steering apparatus including the hydraulic control valve as an example. FIG. 1 is a schematic configuration diagram of a main part of a rack and pinion type power steering apparatus showing an embodiment of the present invention.
[0010]
The rack and pinion type power steering apparatus 1 has an input shaft 2 connected to a vehicle handle (not shown) and an output shaft 3 connected to the input shaft 2 via a torsion bar 6. The torsion bar 6 is connected to the input shaft 2 via the pin 4 and is connected to the output shaft 3 via the serration 5. The input shaft 2 is rotatably supported inside the housing 7 via a bearing 8 and inside the output shaft 3 via a bush 12. The output shaft 3 is rotatably supported inside the pinion case 9 via bearings 10 and 11. A pinion 15 is formed integrally with the output shaft 3, and a steering wheel (not shown) is connected to a rack 16 that meshes with the pinion 15. Thus, when the handle is operated, the input shaft 2 rotates, and the rotation is transmitted to the pinion 15 integrated with the output shaft 3 via the torsion bar 6, and the rack 16 is moved in the vehicle width direction by the rotation of the pinion 15. As a result, the vehicle is steered.
[0011]
The rack 16 is provided with a hydraulic cylinder 20 as a hydraulic actuator that applies assisting force for steering operation. The hydraulic cylinder 20 has a cylinder tube 24 connected to the pinion case 9 and a piston 21 integrated with the rack 16. In order to supply pressure oil to the oil chambers 22 and 23 in the cylinder tube 24 partitioned by the piston 21 according to the steering direction and the steering resistance, according to the torsion angle of the torsion bar 6 on the outer periphery of the input shaft 2. A main hydraulic control valve 30 is provided for operation.
[0012]
The hydraulic control valve 30 includes the above-described tubular housing 7, a tubular valve member 31 that is inserted into the housing 7 so as to be relatively rotatable and surrounds the input shaft 2, and the valve member 31. Seal rings 60, 61, 62, and 63 (see FIG. 3) fitted in circumferential grooves 64, 65, 66, and 67 (see FIG. 3) formed on the outer periphery, respectively.
[0013]
The valve member 31 is connected to the output shaft 3 through a pin 32 so as to rotate integrally. Further, an inlet oil chamber 34 connected to the pump 33, an outlet oil chamber 36 connected to the tank 35, and one oil chamber 22 of the hydraulic cylinder 20 are connected between the valve member 31 and the housing 7. A first oil chamber 37 and a second oil chamber 38 connected to the other oil chamber 23 are provided.
[0014]
These oil chambers 34, 36, 37, 38 are arranged along the axial direction. The outlet oil chamber 36 is disposed above the valve member 31 in FIG. The first oil chamber 37, the inlet oil chamber 34, and the second oil chamber 38 are arranged in this order from above, and are arranged between the inner and outer peripheries of the housing 7 and the valve member 31.
Adjacent oil chambers 34, 36, 37, 38 are partitioned by the above-described seal rings 60, 61, 62. That is, the seal ring 60 is between the outlet oil chamber 36 and the first oil chamber 37, the seal ring 61 is between the first oil chamber 37 and the inlet oil chamber 34, and the seal ring 62 is between the inlet oil chamber 34 and the first oil chamber 34. 2 between the two oil chambers 38. A seal ring 63 is disposed below the second oil chamber 38.
[0015]
The oil chambers 34, 36, 37, and 38 communicate with each other via a flow path between the input shaft 2 and the valve member 31, and the flow path is formed between the input shaft 2 and the valve member 31 due to torsion of the torsion bar 6. The opening degree is adjusted by relative rotation.
That is, as shown in FIG. 2, concave portions 50 are formed along the axial direction at eight circumferentially spaced intervals on the inner periphery of the valve member 31, and the convex portions 51 are formed on the outer periphery of the input shaft 2 facing the concave portions 50. Is formed. As for the recessed part 50, what is connected to the 1st oil chamber 37 via the flow path 53 and what is connected to the 2nd oil chamber 38 via the flow path 54 are alternately parallelly arranged in the circumferential direction. Further, a portion between the circumferential directions of the recesses 50 is a portion that communicates with the inlet oil chamber 34 via the flow passage 55, and an outlet oil chamber 36 that passes between the inner and outer periphery of the flow passage 52, the torsion bar 6, and the input shaft 2. The parts leading to are alternately arranged in the circumferential direction.
[0016]
In a state where steering is not performed, as shown in FIG. 2, the inlet oil chamber 34 and the outlet oil chamber 36 communicate with each other, and no pressure oil is supplied to the oil chambers 22 and 23 of the hydraulic cylinder 20.
When the torsion bar 6 is twisted by the steering resistance generated by steering to the left or right and the valve member 31 and the input shaft 2 are rotated relative to each other, the relative positions of the recess 50 and the protrusion 51 change. Due to this relative position change, the opening of the oil passage from the inlet oil chamber 34 to the first oil chamber 37 between the valve member 31 and the input shaft 2 is increased, and the first oil chamber 37 to the outlet oil chamber 36 is increased. The oil passage becomes smaller, the opening of the oil passage from the inlet oil chamber 34 to the second oil chamber 38 becomes smaller, and the opening of the oil passage from the second oil chamber 38 to the outlet oil chamber 36 becomes larger. As a result, pressure oil having a pressure corresponding to the steering direction and the steering resistance is supplied to the oil chamber 22 of the hydraulic cylinder 20, and the oil flows back from the oil chamber 23 to the tank 35, thereby assisting steering to the left and right of the vehicle. A force acts on the rack 16 from the hydraulic cylinder 20.
[0017]
When the left and right are steered, the valve member 31 and the input shaft 2 rotate relative to each other in the opposite direction, and the opening of the oil passage from the inlet oil chamber 34 to the second oil chamber 38 increases. The opening of the oil passage from the second oil chamber 38 to the outlet oil chamber 36 is reduced, the opening of the oil passage from the inlet oil chamber 34 to the first oil chamber 37 is reduced, and from the first oil chamber 37 The opening of the oil passage to the outlet oil chamber 36 is increased. As a result, steering assist force to the other side of the vehicle acts on the rack 16 from the hydraulic cylinder 20.
[0018]
When pressure oil is supplied from the inlet oil chamber 34 to the oil chamber 22 of the hydraulic cylinder 20 through the first oil chamber 37, the housing 7 and the valve member 31 are interposed between the seal ring 60 and the seal ring 62. The hydraulic pressure between the inner and outer circumferences increases. 4, the uppermost seal ring 60 is pressed against the upper side surface 64a of the peripheral groove 64 and the inner peripheral surface 7a of the housing 7 as shown in FIG. The third seal ring 62 from above is pressed against the lower side surface of the circumferential groove 66 in the figure and the inner peripheral surface 7 a of the housing 7.
[0019]
Further, when pressure oil is supplied from the inlet oil chamber 34 to the hydraulic cylinder 20 via the second oil chamber 38, between the second seal ring 61 and the lowermost seal ring 63 from the upper side in the figure, The hydraulic pressure between the inner and outer circumferences of the housing 7 and the valve member 31 increases. With this hydraulic pressure P, as shown in FIG. 5, the second seal ring 61 from above is pressed against the upper side surface of the circumferential groove 65 in the drawing and the inner peripheral surface 7 a of the housing 7. The lowermost seal ring 63 in the drawing is pressed against the lower side surface of the circumferential groove 67 in the drawing and the inner peripheral surface 7 a of the housing 7.
[0020]
As described above, in the hydraulic control valve 30, the seal ring is pressed against the inner peripheral surface 7 a of the housing 7 and one side surface of each peripheral groove by hydraulic pressure, thereby sealing between the housing 7 and the valve member 31.
The circumferential grooves 64, 65, 66, 67 and the seal rings 60, 61, 62, 63 are similarly configured. Hereinafter, the combination of the circumferential groove 64 and the seal ring 60 will be mainly described.
[0021]
6 to 8 are sectional front views of the circumferential groove and the seal ring shown in FIG. 3, in which FIG. 7 shows a low temperature state and FIG. 8 shows an operating state.
The seal ring 60 is an annular sealing member made of polytetrafluoroethylene (PTFE) and has a substantially rectangular cross section. The outer peripheral edge portion is processed so as to be a rounded surface. On the other hand, the inner peripheral edge 60e is not chamfered and has corners.
[0022]
The circumferential groove 64 is a groove formed on the outer periphery of the valve member 31 and extending in the circumferential direction. The circumferential groove 64 is formed in a substantially rectangular cross section, and has a pair of opposing side surfaces 64a and 64b and a groove bottom 64c that connects the inner peripheral edges of the both side surfaces 64a and 64b. Each of the entrance edges of the circumferential groove 64 is chamfered 64 g.
In addition, at both corners 64f of the groove bottom 64c of the circumferential groove 64, there are provided relief portions 64e that are concave portions that avoid contact with the inner peripheral edge portion 60e of the seal ring 60.
[0023]
Each relief portion 64 e is formed over the entire circumference of the circumferential groove 64. Each relief portion 64e is provided with a rounded surface connected to the corresponding side surface 64a, 64b. The boundary position between the side surfaces 64a and 64b of the circumferential groove 64 and the rounded surface of the corner portion 64f of the groove bottom 64c is more than the portion at the groove bottom 64c and between the relief portions 64e of both corner portions 64f. The valve member 31 is formed so as to be radially inward of the member 31.
Further, as shown in FIG. 8, the width of the relief portion 64 e is larger than the difference between the width of the seal ring 60 and the width of the circumferential groove 64. Therefore, in a state where the seal ring 60 is pressed against the one side surface 64a of the circumferential groove 64, the pressure oil flowing through the gap between the seal ring 60 and the other side surface 64b of the circumferential groove 64 passes through the inside of the escape portion 64e. Thus, it can be introduced into the groove bottom 64c.
[0024]
According to the seal ring 60 and the circumferential groove 64, as described above, due to the hydraulic pressure P, the seal ring 60 is separated from the upper side surface 64 a of the circumferential groove 64 in FIGS. 7 and 8 and the inner circumferential surface 7 a of the housing 7. And pressed against. At this time, the inner peripheral edge 60e of the seal ring 60 and the corner 64f of the circumferential groove 64 do not rub against each other, so that the rotational resistance when the valve member 31 is rotated in the housing 31 can be reduced. There is an annular gap between the inner circumference of the seal ring 60 and the portion of the groove bottom 64c of the circumferential groove 64 and between the relief portions 64e of both corners 64f .
[0025]
Thus, according to the present embodiment, the corner portion 64f of the circumferential groove 64 and the inner peripheral edge portion 60e of the seal ring 60 do not rub against each other, so that the friction between the seal ring 60 and the circumferential groove 64 can be reduced. The chamfering process of the inner peripheral edge 60e of the seal ring 60 can be omitted. As a result, the processing cost of the seal ring 60 can be reduced, and the hydraulic control valve 30 can be made inexpensive.
[0026]
Further, when the relief portion 64e is provided, there is a concern about an increase in processing cost for that purpose, but there is no concern. This is because the peripheral groove 64 has been conventionally cut, and by cutting the relief groove 64e simultaneously with the peripheral groove cutting, the number of processes is not increased, and an increase in processing cost can be suppressed. In addition, the cutting tool necessary for this purpose is dedicated to the shape corresponding to the circumferential groove 64 with the relief portion 64e, but since the cutting tool for machining the conventional circumferential groove was originally dedicated. There is no worry about the cost increase of cutting tools.
[0027]
In particular, when the seal ring 60 is formed of PTFE, since PTFE is a material that is difficult to process, the cost reduction effect by omitting the chamfering process is high.
By the way, when the oil temperature is low, the seal ring 60 may stick to the groove bottom 64c of the circumferential groove 64 (see FIG. 7). This is because the valve member 31 having the circumferential groove 64 is usually made of metal and the seal ring 60 is made of resin, so that the degree of thermal contraction of the seal ring 60 is larger than that of the valve member 31. As described above, when the seal ring 60 is attached to the groove bottom 64c, a gap is formed between the outer peripheral surface 60d of the seal ring 60 and the inner peripheral surface 7a of the housing 7, and the pressure oil enters the oil chamber on the low pressure side through this gap. A so-called hydraulic blow-out phenomenon that flows out may occur.
[0028]
In the hydraulic control valve 30 of the present embodiment, even when the seal ring 60 is stuck to the groove bottom 64c as shown in FIG. 7 at a low temperature, when the hydraulic pressure rises, the hydraulic oil circulates through the relief portion 64e. Since it is guided to the groove bottom 64c of the groove 64, the outer peripheral surface 60d of the seal ring 60 is reliably pressed against the inner peripheral surface 7a of the housing 7, so that the space between the housing 7 and the valve member 31 can be reliably sealed. Yes (see FIG. 8).
[0029]
Further, when the hydraulic control valve 30 is applied to a hydraulic power steering device, an increase in rotational resistance when the valve member 31 is rotated can be prevented, so that an appropriate steering operation force and steering assist force can be obtained. As a result, it is possible to prevent a decrease in steering feeling, which is a feeling of comfort during operation.
In addition, since the above-described hydraulic pressure blow-off phenomenon can be prevented, even when the oil temperature is low, a sufficient steering assist force can be obtained in advance. As a result, the steering torque for operating the steering wheel at that time can be ensured. Can be reduced. As a result, it is possible to suppress variations in steering torque from the start to the time of driving.
[0030]
Further, since the hydraulic control valve 30 can be realized at low cost, the hydraulic power steering device can also be reduced in price.
In the above-described embodiment, the seal ring 60 has been described in which the inner peripheral edge portion 60e is not chamfered. However, the inner peripheral edge portion 60e of the seal ring 60 may be chamfered. For example, it is possible to use the seal ring 60 whose chamfered inner peripheral edge portion 60e has a low accuracy, is small, or has a rough finish with burrs, burr, and the like.
[0031]
Moreover, although the above-mentioned escape part 64e was formed in the groove bottom 64c of the circumferential groove 64, in addition to the groove bottom 64c, you may form in the side surfaces 64a and 64b.
Further, although the hydraulic control valve 30 has been described as being provided in the rack and pinion type hydraulic power steering apparatus, it is not limited to this. For example, it can be applied to a ball screw type hydraulic power steering apparatus. In short, the present invention includes a cylindrical housing, a valve member that is rotatably inserted into the housing, and a seal ring that is fitted in a circumferential groove formed on the outer periphery of the valve member. The present invention can be applied to a hydraulic control valve in which the space between the housing and the valve member is sealed by pressing the ring against the inner peripheral surface of the housing and one side surface of the peripheral groove by hydraulic pressure.
[0032]
In addition, various design changes can be made without changing the gist of the present invention.
[0033]
【The invention's effect】
According to the first aspect of the present invention, the chamfering process of the inner peripheral edge can be omitted, and the friction between the seal ring and the circumferential groove when the housing and the valve member are rotated relative to each other can be reduced. .
Further, since the hydraulic pressure that rises at a low temperature is guided to the groove bottom of the circumferential groove through the relief portion, the seal ring is reliably pressed against the inner peripheral surface of the housing, so that the sealing performance by the seal ring can be reliably ensured. .
[Brief description of the drawings]
FIG. 1 is a front view showing a schematic configuration of a rack and pinion type power steering apparatus according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the hydraulic control valve shown in FIG.
3 is a cross-sectional front view of the main part of the hydraulic control valve shown in FIG. 1, showing a non-operating state.
4 is a cross-sectional front view of the main part shown in FIG. 3, showing an operating state.
5 is a cross-sectional front view of the main part shown in FIG. 3, showing an operating state different from FIG.
6 is a cross-sectional front view of the circumferential groove and the seal ring shown in FIG. 3. FIG.
7 is a cross-sectional front view of the circumferential groove and the seal ring shown in FIG. 6 and shows a low temperature state.
8 is a cross-sectional front view of the circumferential groove and the seal ring shown in FIG. 6, showing an operating state.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rack and pinion type steering device 7 Housing 7a Inner peripheral surface 30 Hydraulic control valve 31 Valve member 60 Seal ring 60e Inner peripheral edge 64 Circumferential groove 64a side surface ( one side surface )
64b Side surface 64c Groove bottom 64e Escape portion 64f Corner portion

Claims (1)

A cylindrical housing; a valve member rotatably inserted into the housing; and a seal ring fitted in a circumferential groove formed on the outer periphery of the valve member. In the hydraulic control valve in which the space between the housing and the valve member is sealed by being pressed against the peripheral surface and one side surface of the peripheral groove,
At both corners of the groove bottom of the circumferential groove, a relief part composed of a recess that avoids contact with the inner peripheral edge of the seal ring, and a round surface that connects the relief part and the side surface of the circumferential groove to each other are provided,
The boundary position between the side surface of the circumferential groove and the rounded surface at the corner of the groove bottom is radially inward of the valve member rather than the portion at the bottom of the groove and between the relief portions at both corners. So that the valve member is formed,
With respect to the direction in which both side surfaces of the circumferential groove face each other, the width of the relief portion at each corner of the groove bottom is made larger than the difference between the width of the seal ring and the width of the circumferential groove,
When the seal ring is pressed against the inner peripheral surface of the housing by hydraulic pressure, it is between the inner periphery of the seal ring and the portion at the bottom of the peripheral groove between the relief portions at both corners. A hydraulic control valve characterized by having an annular gap.

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