JPS6312047Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a rack and pinion type steering device, and in particular to a rack and pinion type power rudder with a so-called tie rod center connection type in which two tie rods are connected to one side of the rack shaft. related to the collecting device.

[Prior Art] This type of rack and pinion power steering device has tie rods that transmit power to the left and right wheels connected to the rack shaft near the joint of the coaxial rack shaft and pinion shaft. There is no need for the piston shaft to pass through the piston of the power cylinder and exit the cylinder chamber, and the pressure receiving area on the left and right sides of the piston differs only by the cross-sectional area of the piston shaft, resulting in a difference in the output (thrust) on the left and right sides of the piston. .

[Problems to be solved by the invention] In order to reduce this output difference, it is necessary to make the diameter of the piston shaft as small as possible. However, in addition to transmitting the output to the rack shaft, the piston shaft has a bearing clearance that allows for slight bending of the piston shaft itself, slight misalignment due to the connection between the rack shaft and the piston shaft, and axial sliding of the rack shaft. Due to such factors, as the rack shaft and piston shaft move in the axial direction during operation, the axes of the piston shaft and rack shaft may deviate from a straight line, become bent or misaligned, and repetitive bending force is applied to the piston shaft. There is a drawback that it is difficult to make the piston shaft small in diameter.

The present invention aims to reduce the diameter of the piston shaft as much as possible, and provides a rack and pinion type power steering device that reduces the repetitive bending force acting on the piston shaft.

[Means for solving the problem] The present invention to solve the above problem is to provide the rack shaft and the piston shaft of the power cylinder on the same axis, and connect two tie rods to the piston shaft side of the rack shaft. and the piston shaft and the rack shaft of a rack and pinion power steering device which steers a vehicle by switching an oil passage leading to the power cylinder by rotation of a pinion shaft having a pinion that meshes with a rack provided on the rack shaft. are formed separately, the diameter of the piston shaft is smaller than the diameter of the rack shaft, the rack shaft end of the piston shaft and the piston shaft end of the rack shaft are connected, and the piston shaft A seal comprising a piston that divides the power cylinder into two at a shaft end on the side opposite to the rack shaft, the rack shaft being pivotally supported in a housing near the joint with the tie rod, and the piston shaft being fixed to the end of the power cylinder. In a rack and pinion type power steering device that is supported in a case via a bearing holder, the shaft end of the piston shaft on the rack shaft side is formed into a conical convex surface concentric with the rack shaft, and a center hole is formed in the end surface of the rack shaft on the piston shaft side. is provided and fitted to the conical convex surface, then both shafts are connected, and the bearing holder is fitted to the seal case with a diametrical gap, keeping the gap oil-tight, and the bearing holder an elastic member is interposed so that the piston can move in the diametrical direction, the piston is fitted into the power cylinder with a diametrical gap, the gap is kept oil-tight, and the piston is movable in the diametrical direction. This is a rack and pinion type power steering device characterized by interposing an elastic member as shown in FIG.

[Function] Since the structure is as described above, the piston shaft and the rack shaft fit together through the conical convex surface and the center hole, and are press-fitted together, and it is possible to avoid misalignment and twisting of the connecting part due to the connection of both shafts, and the piston shaft The piston shaft is not subjected to repeated bending force due to the axial movement of the piston.

In addition, an elastic member is interposed between the piston and the power cylinder so that it can move in the diametrical direction while maintaining oil tightness, and a bearing holder that supports the piston shaft is connected to a seal case fixed to the end of the power cylinder. An elastic member is inserted to allow movement in the diametrical direction while maintaining oil tightness, so even if the rack shaft moves in the diametrical direction due to the rack shaft bearing clearance, the bearing holder and piston will follow and move in the diametrical direction. The moving piston shaft is not subject to repeated bending forces.

[Example] An example of the present invention will be described based on the drawings.
In FIG. 1, which shows the neutral state of the steering system, a rack shaft 1 is rotatably supported by a rack bearing 5 in a housing 11 that connects a gear case (not shown) and a cylinder 6 of a power cylinder. The rack bearing 5 is fixed to the outer peripheral surface of the rack shaft 1, and the housing 1
There is a bearing clearance between the inner circumferential surface of 1 and the inner peripheral surface of 1. Two tie rods 2 are attached to the rack shaft 1 on both sides of the rack bearing 5.
0 are connected with bolts 21. The rack shaft 1 extends to the right in the figure, toward the gear case (not shown), and has a rack that meshes with the pinion of a pinion shaft rotatably supported by the gear case. The connecting portion is located approximately at the center of the entire length from the gear case to the cylinder 6. A piston 22 is oil-tightly fitted into the inner peripheral surface of the cylinder 6, and there is a gap 13 between the piston 22 and the inner wall of the cylinder 6 on both sides of a sealing member consisting of a Teflon ring 23 and an O-ring 24.

The left end of the cylinder 6 is a blind cylinder cover in the form of a bag, and the seal holder 7 is fitted into the right end and fixed together with the housing 11 with a cylindrical nut 25. Reference numeral 26 is a retaining ring, and 27 is a locking nut. The seal holder 7 has a wall portion that protrudes diametrically inward, and the bearing holder 8, which has one end in contact with this wall portion, is fitted onto the inner circumferential surface of the seal holder 7 with a gap 12. There is. This clearance 12 is approximately the same amount as the clearance 13 between the piston 22 and the cylinder 6. In order to keep this gap 12 oil-tight, a
A packing 9 and an O-ring 10 fit into the circumferential groove of the strip and come into elastic contact with the outer circumferential surface of the bearing holder 8. Further, in order to maintain an oil-tight space between the piston shaft 2 and the bearing holder 8, another packing 28 is fitted to the inner circumferential surface of the bearing holder. A bearing 29 is fitted into the inner circumferential surface of the bearing holder 8 and pivotally supports the piston shaft 2 with this packing 28 and a wall protruding from the inner circumferential surface of the bearing holder 8 in between. Further, a restraining plate 30 in contact with the packing 28 is fixed to the seal holder 7 by a retaining ring 31. In the illustrated neutral state, the piston shaft 2 to which the piston 22 is fixed is supported approximately at its center in the axial direction by the bearing 29, and the right rack shaft side end is formed into a concentric conical convex surface 34. The rack shaft 1 has a much larger diameter than the piston shaft 2 and is formed separately, and has a threaded portion 3 with a diameter one step smaller on the piston shaft side than the tie rod joint.
2 are provided. The threaded portion 32 still has a larger diameter than the piston shaft 2, and has a center hole 35 in its end face. A cylinder in which the conical convex surface 34 of the piston shaft is fitted into the center hole 35 of the rack shaft 1, and a step provided on the inner peripheral surface is engaged with a retaining ring 3 fixed to the outer peripheral surface near the shaft end of the piston shaft 2. The nut 4 is screwed into the threaded portion 32 at the shaft end of the rack shaft, and the nut 33 is used to prevent loosening. Figures 2 to 4 show the bearing holder 8.
The packings 9 fit into the outer peripheral surface of the bearing holder 8 and elastically support the bearing holder 8 so as to be movable in the diametrical direction while keeping the bearing holder 8 oil-tight with respect to the seal case 7. In place of the O-ring 10, in FIG. 2, a cylindrical elastic member 14 having two circumferential protrusions 36 is vulcanized and formed on the outer peripheral surface of the bearing holder 8, and in FIG. An elastic member 15 having two protrusions 37 with a semicircular cross section and a space 39 is bonded to a bearing holder 8. FIG. 4 shows an elastic member 16 having two protrusions 38 with a trapezoidal cross section and a space 39. The bearing holder 8 is shown bonded to the bearing holder 8, both of which are intended to reduce costs, and those with spaces are intended to improve elasticity.

In the rack and pinion type power steering device of the present invention constructed as described above, the rack shaft 1 and the piston shaft 2 are fitted with each other through the conical convex surface 34 and the center hole 35, so that the slight misalignment due to the connection of both shafts can be avoided. There is no bending of the piston shaft 2, and the piston shaft 2 is not subjected to repeated bending force due to axial movement of the piston shaft 2.

Further, an O-ring 24 which is an elastic member is interposed so that the piston 22 can move in the diametrical direction while maintaining oil tightness with respect to the cylinder 6 of the power cylinder, and the bearing holder 8 is oil tight with respect to the seal case 7. Since the packing 9 and O-ring 10, which are elastic members, are interposed so that the rack can move in the diametrical direction while maintaining Even if the shaft 1 moves in the diametrical direction, the bearing holder 8 and the piston 22 follow and move in the diametrical direction, and since there is no place to serve as a fulcrum, the piston shaft 2
is not subjected to repeated bending forces. moreover,
Since there is no misalignment or bending of the connecting part between the rack shaft 1 and the piston shaft 2, it is possible to assemble the bearing holder 8 and the seal case 7, and between the piston 22 and the cylinder 6 with clearances around the entire circumference. Therefore, the above-mentioned diametrical movement of the bearing holder 8 and the piston 22 is sufficiently ensured.

[Effects of the invention] As described above, according to the invention, there is no misalignment or bending of the joint between the rack shaft and the piston shaft, so the piston shaft is repeatedly subjected to bending force due to axial movement of the piston shaft. Furthermore, even if the rack shaft moves in the diametrical direction, the bearing holder and the piston follow and move in the diametrical direction, and since there is no fulcrum point, the piston shaft is not subjected to repeated bending forces.

As a result, the diameter of the piston shaft can be reduced, the difference in the pressure receiving area between the left and right sides of the piston is reduced, and the excellent effect is that the difference between the left and right outputs relative to the rack shaft can be extremely small.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a vertical sectional view of a rack shaft showing the main parts of a rack and pinion type power steering device; FIGS. 2, 3, and 4 show different bearings. It is a vertical sectional view showing an embodiment of the holder, and FIGS. 3 and 4 are enlarged views showing only a portion thereof. Explanation of symbols, 1: Rack axis, 2: Piston axis,
5: Rack bearing, 6: Cylinder, 7: Seal holder, 8: Bearing holder, 9: Packing, 10: O
Ring, 11: Housing, 12, 13: Gap, 14, 15, 16: Elastic member, 20: Tie rod, 22: Piston, 34: Conical convex surface, 35:
center hole.

Claims (1)

[Scope of utility model registration request] The rack shaft and the piston shaft of the power cylinder are coaxially provided, two tie rods are connected to the piston shaft side of the rack shaft, and the power cylinder is rotated by the rotation of the pinion shaft having a pinion that meshes with the rack provided on the rack shaft. The piston shaft and the rack shaft of a rack and pinion power steering device that steers the vehicle by switching an oil passage leading to the shaft are formed separately, and the diameter of the piston shaft is made smaller than the diameter of the rack shaft,
The shaft end of the piston shaft on the rack shaft side and the shaft end of the rack shaft on the piston shaft side are connected, and the shaft end of the piston shaft on the side opposite to the rack shaft is provided with a piston that divides the power cylinder into two, and the rack shaft In the rack and pinion type power steering device, the piston shaft is pivotally supported in a housing near the joint with the tie rod, and the piston shaft is supported via a bearing holder in a seal case fixed to the end of the power cylinder. The shaft end on the rack shaft side is formed into a conical convex surface concentric with the rack shaft, and a center hole is provided in the end surface on the piston shaft side of the rack shaft to fit into the conical convex surface, and then both shafts are connected. is fitted into the seal case with a gap in the diametrical direction, an elastic member is interposed in the gap to maintain oil tightness and the bearing holder can move in the diametrical direction, and the piston is connected to the power cylinder. 1. A rack and pinion type power steering device, characterized in that the pistons are fitted with a diametrical gap, and an elastic member is interposed in the gap to maintain oil tightness and allow the piston to move in the diametrical direction.