JPH0126912B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering device, and more particularly to a power steering device in which a control valve for controlling the supply and discharge of pressure fluid to and from a power cylinder is of a rotary type.

Generally, a rotary type control valve has a valve rotor that is integrally provided on an input shaft on the steering wheel side and an output shaft on the steering wheel side that can rotate around the outer circumference of the valve rotor. and a valve sleeve, and when the valve is operated, the rotational displacement from the neutral state is caused between the input shaft and the output shaft, that is, between the valve rotor and the valve sleeve. , the direction in which pressure fluid is supplied and discharged to and from the power cylinder is controlled. Conventionally, the input shaft and the output shaft are connected via a torsion bar, and the torsion force of the torsion bar allows the valve rotor and the valve sleeve to be maintained in a neutral state when the valve is not in operation. However, due to the structure of the torsion bar, when the left and right torsional force is zero, the valve rotor and valve sleeve must be in a neutral state, and for this reason, it is impossible to apply preload between the input and output shafts with the torsion bar. It is.

For this reason, conventionally, in addition to or in place of the torsion bar, a C-shaped spring has been used in which a part of a ring-shaped spring material is cut out to form a substantially C-shape, and the input shaft is connected between the notches of the C-shaped spring. A power steering device has been proposed in which an integral protrusion and an integral protrusion on the output shaft are simultaneously clamped with a predetermined elastic force, thereby making it possible to maintain both shafts in a neutral state and at the same time apply preload. has been done.

However, in this type of power steering device, if there is a gap between the inner circumferential surface of the C-shaped spring that clamps the pair of protrusions and the outer circumferential surface of a member located inside this C-shaped spring, such as a valve sleeve. When the input/output shaft is rotated relative to each other and the pair of protrusions are operated in a direction away from each other, the spring is tilted as both protrusions operate, and this spring touches the outer peripheral surface of the valve sleeve. Until the two protrusions come into contact with each other and cannot tilt any further, it becomes impossible to apply a resiliency force to return the two protrusions to their neutral positions. Furthermore, even if the gap is eliminated, if the gap between the notches in the C-shaped spring is widened by the operation of both protrusions, the inner diameter of the spring will become larger and a gap will inevitably be created between the spring and the outer peripheral surface of the valve sleeve. As a result, this spring clamps both protrusions while tilting as described above. Therefore, with the above-mentioned gap, it is impossible to return the valve rotor and valve sleeve to the correct neutral position, and even with a valve without the gap, the inclination of the spring during operation makes it impossible to return the valve rotor and valve sleeve to the neutral position. The elastic force applied to the protrusion fluctuated, and there was a risk that the steering sensation would be adversely affected.

The present invention was made in view of the current situation, and its purpose is to prevent the spring from tilting with respect to the axial direction of the two shafts when a preload is applied between the input and output shafts by the elastic force of the spring. It is an object of the present invention to provide a power steering device that can prevent this and accurately and reliably hold a rotary type control valve in a neutral state.

The present invention will be described below based on an illustrated example of implementation.

In FIG. 1, 1 is an input shaft, and the input shaft 1 and output shaft 2 are arranged on the same axis.
A protrusion 3 protruding from the end shaft of the input shaft 1 is rotatably fitted into a bushing 4 fitted to the end shaft of the output shaft 2, and the input shaft 1 and the output shaft 2 are In this state, it is rotatably supported within the housing 5 via a bearing 6. The input shaft 1 is linked to a steering wheel (not shown), and a helical pinion 7 (not shown) is formed at the tip of the output shaft 2, similar to a conventionally known rack and pinion power steering device. It meshes easily with the steering wheel.

As shown in FIGS. 1 to 3, a roughly rectangular engagement portion 8 is provided at the tip of the input shaft 1 in front of the protrusion 3, and the output shaft 2 receives the engagement portion 8. Grooves 9 are respectively formed, and the engaging portions 8 are disposed within the grooves 9 with a required gap in the circumferential direction. Therefore, the input shaft 1 and the output shaft 2
and allow relative rotation by the amount permitted by the gap. The engaging portion 8, that is, the input shaft 1, and the vicinity of the groove 9, that is, the output shaft 2 have protrusions 10, respectively.
11 is provided, and a protrusion 17 is provided on a stepped portion 14b of the valve sleeve 14, which will be described later, and is integral with the stepped portion 14b. It is held between both end surfaces of the notch 12a of the C-shaped spring 12 provided. At this time, the interval 1 in the circumferential direction between the notches 12a of the C-shaped spring 12 in the natural state (see Fig. 2) is set smaller than the length in the same direction of each projection 10, 11, 17 having the same dimensions. Therefore, with this C-shaped spring 12, each of the projections 10, 11, 17
A desired preload can be applied between the input and output shafts 1 and 2 by sandwiching them. It goes without saying that when no external force is applied to the input/output shafts 1 and 2, the engaging portion 8 is held at a neutral position with respect to the rotational direction of the groove 9 by the C-shaped spring 12.

However, the valve rotor 1 is connected directly to the input shaft 1.
3 is formed, and a valve sleeve 14 is rotatably fitted around the outer periphery of this valve rotor 13, basically forming a conventionally known rotary type control valve. The end portion of the valve sleeve 14 on the output shaft 2 side is
an axial engagement groove 15 formed as a cylindrical portion 14a that can be fitted into the portion 2a of the output shaft 2 provided with the protrusion 11, and having a width matching the circumferential width of the protrusion 11 in the cylindrical portion 14a; A through hole 16 is formed to allow the protrusion 10 to pass therethrough and to allow the protrusion 10 to be displaced in the circumferential direction. The cylindrical portion 14a is located inside the C-shaped spring 12 as shown in FIGS. The projections 10 are integrally connected in the rotational direction, and the protrusion 10 is loosely fitted through the through hole 16 at least on both sides in the rotational direction at a predetermined interval. Further, as shown in FIG. 2, the step portion 14b formed at the end portion of the cylindrical portion 14a has a protrusion 17 that protrudes in the direction of the protrusion 11 at the same position in the circumferential direction as the axial engagement groove 15. It is integrally formed. Although it is difficult to integrally provide the protrusion 17 on the valve sleeve 14 by machining, it can be easily manufactured by using a sintered material or the like. Conversely, the protrusion 17 may be configured as a pin separately from the valve sleeve 14, and the pin may be press-fitted into the valve sleeve 14.

As shown in FIG.
The side protrusions 11 and 17 are located on both sides of the input shaft 1 via the protrusion 10. Therefore, the sixth
As shown in the figure, when the input shaft 1 is rotated in one direction and relative rotation occurs between the protrusions 11, 17 and the protrusion 10 against the elastic force of the C-shaped spring 12, the C
One end surface of the notch 12a of the shaped spring 12 has a protrusion 1
This is supported by two points, 1 and 17. Therefore, even if there is a large gap between the inner circumferential surface of the C-shaped spring 12 and the cylindrical portion 14a of the valve sleeve 14 in the natural state, the C-shaped spring 12
There is no risk of tilting with respect to the axial direction of No. 2.

In the neutral state, the control valve composed of the valve rotor 13 and the valve sleeve 14 simply circulates pressure fluid from a pump (not shown). That is, the pressurized fluid from the pump is supplied through a supply hole 20 formed in the housing 5 and an annular groove 2 formed in the valve sleeve 14, as shown in FIGS. 1 and 4.
1 and the valve rotor 13 via the radial passage 22
Axial grooves 24, 2 formed on the inner surface of the valve sleeve 14 so as to flow into the axial supply groove 23 formed in the valve sleeve 14 and to overlap on both sides of the groove 23 in the circumferential direction.
5 and into an axial exhaust groove 26 formed in the valve rotor 13 so as to overlap both grooves 24, 25. The pressure fluid that has flowed into the discharge groove 26 flows along the groove toward the abutting portion of the input shaft 1 and output shaft 2, and from there flows through the through hole 16 and the notch 12a of the C-shaped spring 12. The liquid flows out to the outer periphery of the valve sleeve 14, and further flows back to the suction side of the pump via a discharge hole 27 provided in the housing 5. The groove 24 on one side of the supply groove 23 communicates with one chamber of a power cylinder (not shown) via a radial passage 28, an annular groove 29, and a supply/discharge hole 30 provided in the housing 5, and similarly communicates with the groove 25 on the other side. It also communicates with the other chamber of the power cylinder through a radial passage 31, an annular groove 32, and a supply/discharge hole 33, but in the neutral state, the supply groove 23 and the grooves 2 on both sides thereof are connected to each other.
4 and 25 are substantially equal, and there is no pressure difference between both grooves 24 and 25, the power cylinder maintains a non-operating state.

On the other hand, when the input shaft 1 is rotated in one direction, the protrusion 10 and the protrusion 11 move against the elastic force of the C-shaped spring 12.
17 and therefore between the valve rotor 13 and the valve sleeve 14, depending on the direction of rotation, the supply groove 23 and the grooves 24, 2 on both sides thereof
When a difference occurs in the flow path area between the grooves 24 and 25, a pressure difference occurs between the grooves 24 and 25. As a result, the power cylinders communicating with each of the grooves 24 and 25 operate to apply an auxiliary force in the steering direction as is conventionally known.

In the above embodiment, the protrusion 11 is fixed to the output shaft 2, and the protrusion 11 is used to integrally connect the output shaft 2 and the valve sleeve 14 in the rotational direction. 2 and a valve sleeve 14 are integrally connected, and the protrusion 1 is attached to the valve sleeve 14.
1 may be provided.

FIG. 7 shows a modification of the present invention, in which the input shaft is rotated in one direction and the relative rotation between the protrusion 10 and the protrusions 11 and 17 is caused by resisting the elastic force of the C-shaped spring 12. In order to reduce the load applied to the protrusion 17 manufactured by sintering when the protrusion 10,1
The length L ₁ between the protrusions 10 and 17 is narrower than the length L ₂ between the protrusions 10 and 17.

That is, due to the elastic force of the C-shaped spring 12, the protrusion 1
The load F applied to the projection 0 is equal to the resultant force of the loads F ₁ and F ₂ applied to the respective protrusions 11 and 17, and the directions thereof are opposite to each other. Therefore, the ratio of loads F ₁ and F ₂ is
The lengths L ₁ and L ₂ from 0 are inverse ratios, and the further away from the protrusion 10 the smaller the load applied.

Therefore, by bringing the protrusion 10 closer to the protrusion 11, the load _F2 applied to the protrusion 17 is reduced to
This value is small compared to the load F ₁ applied to the projection 17, and damage to the relatively weak protrusion 17 is effectively prevented.

In addition, as shown in FIG. 6, one of the protrusions 1
1 and 17 and the other protrusion 10, when the spring 12 is expanded by the protrusion 10 and the other protrusion 10, the protrusion 10 and the spring 12
Since the contact point P with the spring 12 is one point, that point P is the spring 12
If it deviates from the center position (b ₁ = b ₂ ) in the axial direction of The end face on the 10 side may be twisted about the contact point P, and the spring constant may change. Therefore, in order to prevent this, it is desirable that the contact point P is located at the center of the spring 12 in the axial direction. However, if it is necessary to shift the contact point P from the center position due to design reasons, the spring constant may be set in advance by taking into account torsion around the contact point P, or
Alternatively, there may be a plurality of protrusions 10, or even a plurality of protrusions 10.
0 has a rectangular cross section, and measures such as increasing the contact area between this and the spring 12 to reduce the amount of twisting may be taken.

8 to 10 show other embodiments of the present invention. In this embodiment, unlike the previous embodiment, one end of the output shaft 2 is formed into a cylindrical shape, and the input shaft 1 is inserted into the cylindrical portion 2b via a bearing 40.
are fitted. Pins 41 and 42 extending radially outward are fixed to the cylindrical portion 2b, and a through hole 43 is opened between them, and a pin 44 attached to the valve rotor 13 is inserted into the through hole 43.
stands out from A C-shaped spring 12 similar to that of the above embodiment is disposed on the outer periphery of the cylindrical portion 2b, and this spring 12 clamps each of the above pins 41, 42, 44 to provide desired input/output shafts 1, 2. Grant preload. Note that the C-shaped spring 12 is held between a stepped portion 2c formed on the cylindrical portion 2b and a snap spring 46, and its axial movement is restricted.

On the other hand, the valve sleeve 14 and the cylindrical portion 2b of the output shaft 2 are integrally connected by a connecting pin 45 implanted in both, so that relative rotational displacement between the input shaft 1 and the output shaft 2 is prevented. When raised, valve rotor 1
3 and the valve sleeve 14 rotate relative to each other, and the supply and discharge of pressure fluid to and from a power cylinder (not shown) is controlled. FIG. 10 shows the relative rotation between the input and output shafts 1 and 2. Two pins 41 and 42 are in contact with one end surface of the C-shaped spring 12, and this spring 12 Prevents it from tipping. Therefore, in this embodiment, the C-shaped spring 12 does not interfere with the valve sleeve 14, so that the valve sleeve 14 is not directly subjected to the elastic force of the spring 12. Therefore, the valve sleeve 14 can accurately rotate around the axis, and the pressure fluid supply and discharge control can be performed with high precision.

The fitted state of the input shaft 1 and output shaft 2 is so-called fail-safe, as shown in FIG. 9. That is, the protrusion 47 in the axial direction is formed on the outer periphery of the input shaft 1, while the output shaft 2
A groove 48 is formed on the inner periphery of the groove 48 and engages with the protrusion 47 while allowing relative rotation.

The operation of this embodiment is basically the same as that of the above embodiment, so the explanation thereof will be omitted.

As described above, according to the present invention, both the protrusions protrude in the radial direction of each control valve element and are spaced apart along the width direction of the spring between the notches of the C-shaped spring in the neutral state aligned in the axial direction. and at least one control valve element side has a plurality of protrusions, and the other control valve element side has a plurality of protrusions located between the plurality of protrusions, and these protrusions are sandwiched by the spring. Because of this structure, it is easy to set the protrusion from the input/output shaft, and the spring shape is simple, making it possible to have a compact structure that is almost annular surrounding the input/output shaft as a whole.
Moreover, the plurality of protrusions makes it possible to always keep the inclination of the spring constant. Therefore, when applying a preload between the input and output shafts with the spring, and against the elastic force of the spring, the input shaft can be kept in the same position. Even if there is a large gap between the inner circumferential surface of the spring and the outer circumferential surface of a valve sleeve as a control valve element, the spring will not tilt with respect to the axial direction of the input/output shaft when the spring is rotated in the direction. This makes it possible to accurately and reliably maintain the neutral state of the control valve, and
Provides sharp steering characteristics with no play. Furthermore, as mentioned above, since there may be a gap between the inner circumferential surface of the spring and the outer circumferential surface of the valve sleeve, high precision is not required when manufacturing the spring, and therefore manufacturing is easy and free of problems. This reduces the number of non-defective products, which helps reduce costs.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing an embodiment of the present invention, Fig. 2 is an exploded perspective view of the main parts of Fig. 1, and Figs. 5 is an explanatory diagram showing the relationship between each projection and the C-shaped spring in a neutral state, and FIG. 6 is an explanatory diagram showing the relationship between each projection and the C-shaped spring when the input shaft is rotated in one direction. FIG. 7 is an enlarged view of the protrusion and C-shaped spring portion showing a modified example of the present invention, FIG. 8 is a longitudinal cross-sectional view showing another embodiment of the present invention, and FIG.
FIG. 10, which is a sectional view taken along the line - in the figure, is an explanatory view showing the relationship between each protrusion and the C-shaped spring when the input shaft is rotated in one direction. 1: Input axis, 2: Output axis, 10, 11, 17,
41, 42, 44: Protrusion, 12: C-shaped spring, 1
3: Valve rotor, 14: Valve sleeve, 16: Through hole.

Claims (1)

[Claims] 1 Consists of an input shaft linked to the steering wheel, an output shaft linked to the steering wheel disposed on the same axis as the input shaft, and a pair of control valve elements provided on each of the input shaft and output shaft. A rotary type control valve that controls the supply and discharge of pressure fluid to the power cylinder according to the relative rotational displacement of both control valve elements, a protrusion that rotates integrally with each control valve element, and a rotary type control valve that sandwiches both protrusions. a generally C-shaped spring for holding the control valve in a neutral state, the protrusions projecting in the radial direction of each control valve element and extending between the notches of the C-shaped spring in the axially aligned neutral state. A plurality of protrusions are arranged at a distance along the width direction of the spring and on at least one control valve element side, and a protrusion on the other control valve element side is positioned between the plurality of protrusions. is held between the springs.