JPH11222147A - Rack and pinion type steering device and rack shaft used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply fix a cylindrical body fixed to a rack shaft to the rack shaft; and to well make the outer surface of the cylindrical body contact with the inner surface of a rack housing. SOLUTION: This rack and pinion type steering device is provided with a rack housing 3 for housing a rack shaft 2 moved in accordance with steering operation. A cylindrical body 4 for receiving a load acted on the rack shaft 2 from a tie rod 6 installed on the rack shaft at the inner surface of the rack housing 3 is provided on the rack shaft 2. The cylindrical body 4 is provided with a cylindrical main body 41 having a slit part in the axial length direction, of the connecting parts 42 for connecting both the end part of the main body 41 in the peripheral direction extended over the split part, Molding the cylinder body 4 on the rack shaft 2 serving as a core material simply fixes the rack shaft 2 to be the cylindrical body 4. In addition, the outer surface of the cylindrical body 4 wall comes in contact with the inner surface of the rack housing 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rack and pinion type steering device having a rack shaft which moves in the left and right direction of a vehicle body in conjunction with a pinion shaft which rotates in accordance with a steering operation, and a rack shaft used for the same.

[0002]

2. Description of the Related Art As one type of steering apparatus for an automobile, a pinion of a pinion shaft interlockingly connected to a steering wheel (steering wheel) is meshed with rack teeth of a rack shaft extending in the left-right direction of the vehicle body. The rack and pinion is configured to convert the rotation operation of the steering wheel for steering into movement in the axial direction of the rack shaft, and transmit the movement to the left and right steering wheels (generally, the front wheel) to perform steering. There is a type steering device.

[0003] Such a rack-and-pinion type steering device is as follows.
Further, a pair of tie rods for connection with left and right steering wheels are separately connected to both ends of the rack shaft, and an end take-off type in which the tie rods are collectively connected to a middle portion of the rack shaft. It is roughly divided into a center take-off type.

The center take-off type rack-and-pinion type steering apparatus has a large degree of freedom in setting a relative positional relationship between the tie rods to the left and right steered wheels and the steered wheels. It has advantages and is used in some vehicle models.

In the center take-off type rack and pinion type steering apparatus as described above, the rack shaft is movably housed in a cylindrical rack housing. 7A and 7B, a contact force can be brought into contact with the inner surface of the rack housing 101 at a position near the tie rod attachment of the rack shaft 100 as shown in FIGS. A resin cylinder 102 is provided to prevent the rack shaft 100 from bending due to the pressing force.

Since the distance between the axis of the rack shaft 100 and the base end of the tie rod is restricted by user specifications, the cylindrical body 102 has a substantially C-shaped section having a split portion 102a in the axial direction on the tie rod side. Is formed. Further, a through hole 103 is provided at the center of the cylindrical body 102 in the bending direction.
And a pin hole 104 corresponding to the through hole 103 is formed in the rack shaft 100, and a pin 105 is inserted into the pin hole 104 from the through hole 103, whereby the cylindrical body 102 is connected to the rack shaft 100. It is fixed to.

[0007] Further, by providing a pressing member 107 for applying a tightening force of the screw body 106 for attaching the tie rod to the split portion 102a of the cylindrical body 102, and pressing the split portion 102a, the cylindrical body 102 is moved to the rack housing 101. It is configured to be able to satisfactorily come into contact with the inner surface of the.

[0008]

However, the above-mentioned conventional cylinder 102 has a structure which is formed into a substantially C-shaped cross section and is fitted to the rack shaft 100 and fixed by the pins 105. Is difficult to form in a designed circular arc state, and the whole is curved so as to be substantially U-shaped. Therefore, there is a problem that it is difficult for the cylindrical body 102 to bend outward and fit into the rack housing 101, or that the cylindrical body 102 is bent inward and difficult to fit to the rack shaft 100. After the cylindrical body 102 is fitted to the rack shaft 100, it is substantially U to prevent the cylindrical body 102 from dropping off from the rack shaft 100 while being fixed by the pins 105.
By increasing the elastic restoring force of the cylindrical body 102 curved in a letter shape,
It is necessary to grasp by the elastic restoring force. Therefore, when fitting the cylindrical body 102 to the rack shaft 100, it is necessary to forcibly expand the cylindrical body 102 having a large elastic restoring force, and there is a problem that it is difficult to perform the expanding operation and the workability is poor. .

Further, the cylindrical body 102 which is curved so as to have a substantially U-shape as a whole is only fixed at the center and both ends in the arc direction, so that the inner surface of the cylindrical body 102 and the rack shaft 10 are fixed.
A gap is formed between the outer surface of the cylindrical body 102 and the split portion 10 of the cylindrical body 102.
There is a problem that all the outer surfaces between 2a cannot be brought into good contact with the inner surface of the rack housing 101.

Further, since the pin 105 and the holding member 107 are required separately from the cylindrical body 102, the number of parts is large and the cost is high.

The present invention has been made in view of such circumstances, and has a rack shaft as a core material, and a cylindrical body is formed and fixed to the rack shaft, whereby the cylindrical body is easily fixed to the rack shaft. An object of the present invention is to provide a rack-and-pinion type steering device capable of making the outer surface of a cylindrical body come into good contact with the inner surface of a rack housing, and a rack shaft used for the same.

[0012]

According to a first aspect of the present invention, there is provided a steering apparatus including a rack housing for accommodating a rack shaft that moves in the left-right direction of a vehicle body in conjunction with a pinion shaft that rotates in response to a steering operation. In a rack-and-pinion type steering device in which a cylindrical body that receives a load acting on the rack shaft from a tie rod attached to the rack shaft on an inner surface of the rack housing is provided on the rack shaft, the cylindrical body has a longitudinal axis. A cylinder body provided with a split portion and a connecting portion for connecting both circumferential ends of the cylinder body across the split portion are provided, and the rack body is formed on the rack shaft using the rack shaft as a core material. It is characterized by the following.

In a rack shaft according to a third aspect of the present invention, a tubular body is provided on an outer surface of a shaft body to which a steering tie rod is attached, the load acting on the tie rod being received by an inner surface of a rack housing in which the shaft body is housed. In the rack shaft, the cylindrical body includes a cylindrical main body provided with a split portion over its entire length, and a connecting portion for connecting both circumferential end portions of the cylindrical main body across the split portion. The cylindrical body is formed on the shaft main body as a core material.

According to the first and third aspects of the present invention, since the rack shaft is used as the core material and the cylindrical body is formed on the rack shaft, the arc of the cylindrical body can be favorably maintained. Can make good contact with the inner surface of the rack housing. Further, the cylindrical body can be easily fixed to the rack shaft by molding. Further, since the rack shaft is formed, the number of parts can be reduced as compared with the above-described conventional example.

In a steering device according to a second aspect of the present invention, a concavity is provided at a position corresponding to the cylindrical body of the rack shaft, and a restraining portion for restricting the movement of the cylindrical body by entering the concaved part in the cylindrical body. Is formed.

According to the second aspect of the present invention, since the restraining portion formed integrally with the cylindrical body restrains the movement of the cylindrical body, the fixed state of the cylindrical body to the rack shaft is favorably maintained for a long period of time. be able to.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a longitudinal sectional front view of a main part of a rack and pinion type steering apparatus according to the present invention, FIG. 2 is a vertical sectional side view of the same main part, FIG. 3 is a sectional view of the entire rack and pinion steering apparatus, and FIG. FIG. 5 also shows the rack shaft, FIG. 5 (a) is an enlarged sectional view taken along line XX of FIG. 4, (b) is an enlarged sectional view taken along line YY of FIG. 4, (c) ) Is an enlarged bottom view, (d) is an enlarged plan view, and FIG. 6 is a bottom view of only the shaft main body of the rack shaft.

The rack and pinion type steering apparatus shown in FIG. 3 has a pinion shaft 1 having one end linked to a steering wheel (steering wheel) and a pinion (not shown) provided at the other end, and the pinion shaft. A metal rack shaft 2 extending in the left-right direction of the vehicle body; a cylindrical rack housing 3 for movably housing the rack shaft 2; A cylindrical body 4 provided on the rack shaft 2, a cylindrical expandable and contractible boot 5 disposed around the rack housing 3, and a pair of tie rods. One tie rod mounting body 7 holding the base end of 6, 6
And the tie rod mounting body 7 with the rack housing 3
And a threaded body 8, 8 penetrating through the boot 5 and attached to one end of the rack shaft 2, and is a center take-off type rack-and-pinion type steering device.

As shown in FIGS. 1 and 2, the rack shaft 2 is accommodated in the cylindrical rack housing 3 having one end closed so as to be movable in the axial direction. At one end of the rack shaft 2, the cylindrical body 4, an annular recess 21, a detent groove 23 extending in the axial direction, and a mounting hole 22 for mounting the tie rod mounting body 7 are provided. The rack teeth are provided at an intermediate portion on the other end side, and the side opposite to the rack teeth is supported by the rack housing 3 via a guide sheet.

The recess 21 and the detent groove 23 are provided at positions where the cylindrical body 4 is provided as shown in FIG.
Also, as shown in FIGS. 1 and 5, two recesses 21 are provided at predetermined intervals in the axial direction. These recesses 21 and 2
The two mounting holes 22 are provided on the outside of the rack 1 so as to be inclined so as to intersect with the axial length direction of the rack shaft 2, and flat receiving seats 24 are provided in the openings thereof. I have.

The cylindrical body 4 has the rack shaft 2 as a core material, and a synthetic resin material is molded on the outer surface of the rack shaft 2 as shown in FIG.
And a pair of connecting portions 42, 4 for integrally connecting the both ends in the circumferential direction of the cylindrical body 41 across the split portion 4a.
2, a pair of restraining portions 43, 43 which enter the recesses 21, 21 to restrain the cylinder 4 from moving in the axial direction, and enter the detent groove 23 to prevent the cylinder 4 from moving in the circumferential direction. And one restraining portion 44 for restraining the movement.

The cylindrical body 4 is formed by placing one end of the rack shaft 2 in a molding die and filling the die with a synthetic resin material. As shown in FIGS. 4 and 5, the cylindrical body 4 formed in this manner has a cylindrical main body 41 protruding from the outer surface of the rack shaft 2, and the cylindrical main body 41
Connecting part 4 that connects both ends in the circumferential direction of the part to straddle part 4a
2, 42, and constraining portions 43, 43 which enter the recesses 21, 21 to form an annular shape and a part of which also serves as the connecting portions 42, 42;
A restraining portion 44 that enters the detent groove 23 and has a rod shape is integrated, one restraining portion 43 restricts movement of the cylindrical body 4 in the axial length direction, and the other restraining portion 44 controls the cylindrical body 4. Is restricted in the circumferential direction. A plurality of oil retaining grooves 4 extending over the entire length are provided on the outer surface near the center in the bending direction of the cylinder main body 41.
5 and 45 are provided, and a lubricant such as grease is held in these oil retaining grooves 45 and 45.

As shown in FIG. 3, the rack housing 3 is formed in a bottomed cylindrical shape having one end closed and the other end open, and a pinion is provided at a middle portion of the closed side so as to intersect therewith. A housing 9 is continuously provided, and the pinion shaft 1 is supported inside the pinion housing 9 so as to be rotatable around an axis. The rotation of the pinion shaft 1 is slid in the axial direction of the rack shaft 2. It is converted to motion.

As shown in FIG. 3, a window hole 31 for moving the tie rod mounting member 7 with respect to the rack housing 3 is provided in a middle portion of the open side of the rack housing 3, and an area where the window hole 31 is formed. The surrounding area is covered with the boot 5 to prevent foreign substances such as dust and water from entering the rack housing 3 through the window hole 31.

As shown in FIG. 1, the tie rod mounting member 7 has a pair of holding pieces 7 for holding the base end of the tie rod 6.
1, 71 and a pair of cylindrical projections 72, 72 fixed to the holding pieces 71, 71 at a predetermined interval and intersecting the axial direction of the rack shaft 2, and are formed in the holding pieces 71, 71. The screw bodies 8 are inserted into a pair of through holes provided and central holes of the projections 72, and the screw bodies 8 are tightened to the mounting holes 22 of the rack shaft 2. As a result, the projections 72 are brought into contact with the receiving seats 24 of the rack shaft 2, and the tie rod mounting body 7 is arranged outside the boot 5 and fixed.

The boot 5 is made of a flexible synthetic resin, rubber, or the like. As shown in FIG. 3, the elastic portions 51, 51 having bellows at both ends, and these elastic portions 51, 51, A connecting tube portion 52 for connecting the connecting portion 51 is provided. The connecting tube portion 52 is provided with a flat portion 53 facing the tie rod mounting body 7, and the flat portion 53 is fitted with the fitting holes 72 and 72. 54, 54 are provided. Further, both ends of the elastic portions 51, 51 are detachably attached to the rack housing 3 by attachment rings 10, 10.

The rack and pinion type steering device of the embodiment shown in FIG. 3 is configured as a power steering device for assisting the sliding of the rack shaft 2 by hydraulic pressure.
The hydraulic cylinder 11 that applies an auxiliary force to the rack housing 2 extends a piston rod 12 coaxially connected to one end of a rack shaft 2 into a cylinder tube 13 connected to an open end of the rack housing 3. Piston 1 attached to extension end
4 is slidably fitted inside the cylinder tube 13.

The cylinder tube 13 is a closed-end cylindrical member having a closed end opposite to the connection end with the rack housing 3, and has a seal member 15 inside on the connection side with the rack housing 3. The seal holder 16 is mounted. The piston rod 12 is sealed in a liquid-tight manner in the middle part thereof by the
It extends inside.

As described above, the hydraulic cylinder 11 has a pair of oil chambers sealed on both sides of the piston 14 in a liquid-tight manner inside the cylinder tube 13. The piston rod 12 is pushed and pulled in the axial direction by a pressure difference generated on both sides of the piston 14 in response to the feeding, and the rack shaft 2 connected to the base end of the piston rod 12 moves in the axial direction. Is added.

The oil chambers on both sides of the piston 14 are connected to a pair of oil supply ports 91 provided outside the pinion housing 9 by separate oil supply pipes 17, 17 connected respectively to corresponding positions outside the cylinder tube 13. , 92. The pinion housing 9 performs a hydraulic supply / discharge operation in accordance with a steering torque applied to the pinion shaft 1 in accordance with a steering operation for steering.
2 is provided with a known hydraulic control valve for sending oil to the oil supply ports 91 and 92.
The hydraulic cylinder 11 is fed to the hydraulic cylinder 11 through 7, 17, and the hydraulic pressure generated in response to the feed is applied to the rack shaft 2 to assist the steering that occurs as described above.

The center take-off type rack-and-pinion type steering apparatus constructed as described above has a rack shaft 2 as a core material, and a cylindrical body 41 having a split portion 4a on an outer surface of the rack shaft 2 and a cylindrical body 41. Since the cylindrical body 4 is provided with the connecting portions 42, 42 that integrally connect the both ends in the circumferential direction across the split portion 4a, the arc of the cylindrical body 4 can be favorably maintained, The outer surface of the cylindrical body 4 can be brought into good contact with the inner surface of the rack housing 3.
The cylindrical body 4 can be easily fixed to the rack shaft 2. In addition, since the restraining portions 43, 43 for entering the recesses 21, 21 of the rack shaft 2 and restraining the movement are formed integrally with the cylinder main body 41, the fixed state of the cylinder 4 can be maintained for a long period of time. it can.

The rotation of the steering wheel causes the pinion shaft 1 to rotate.
When the rack shaft 2 reciprocates in the axial direction via the tie rods 6 and 6, the tie rods 6 and 6 operate via the tie rod mounting members 7 attached to the rack shaft 2. A pressing force in a direction intersecting with the axial direction acts on the rack shaft 2 via the tie rod mounting body 7, and the cylindrical body 4 is pressed against the inner surface of the rack housing 3 by the pressing force. Therefore, the rack shaft 2 reciprocates with the outer surface of the cylindrical body 4 in contact with the inner surface of the rack housing 3. In this case, since the cylindrical body 4 is made of synthetic resin, the rack shaft 2 can be moved smoothly, and the cylindrical body 4 is formed on the rack shaft 2;
Since the restraining portions 43, 43 enter the recesses 21, 21 of the rack shaft 2 to restrain the movement of the cylinder 4, the fixed state of the cylinder 4 can be maintained for a long period of time.

In the embodiment described above, the cylinder 4
Connecting portion 4 using restraint portions 43, 43 for restraining the movement of
2 and 42 are formed.
May be formed separately from the restraining portions 43, 43. Although one detent groove 23 is provided as a means for restraining the circumferential movement of the cylinder 4, a knurl extending in the axial direction is provided on the outer surface of the rack shaft instead of the detent groove 23. You may. In addition to the provision of the annular recess 21 and the detent groove 23 as means for restraining the movement of the cylindrical body 4, the outer surface of the rack shaft 2 may have a rough surface such as a satin pattern, or may have a rough surface. One or a plurality of appropriately shaped non-circular recesses or protrusions may be provided on the outer surface of the second. Also,
The means for restraining the movement of the cylinder 4 is provided on the rack shaft,
For example, the flat part 53 of the connecting cylinder part in the boot 5 is used, and the flat parts 53 are connected to the connecting parts 43, 43 and the split part 4.
The protrusion may be provided to engage with a to restrict the movement. The cylindrical body 4 may be made of a synthetic resin, or may be made of a material different from the rack shaft 2 such as an aluminum alloy or a sintered metal.

[0034]

As described above in detail, according to the first and third aspects of the present invention, since the rack shaft is used as the core material and the cylinder can be formed on the rack shaft, the arc state of the cylinder can be improved. The outer surface of the cylindrical body can be brought into good contact with the inner surface of the rack housing. In addition, the cylindrical body can be easily fixed to the rack shaft, and the number of components can be reduced as compared with the conventional example using extra pins and holding members for fixing, and the cost can be reduced.

According to the second aspect of the present invention, since the restricting portion formed integrally with the cylindrical body restricts the movement of the cylindrical body, the fixed state of the cylindrical body to the rack shaft can be favorably maintained for a long period of time. Can be.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of a main part of a rack and pinion type steering device according to the present invention.

FIG. 2 is a longitudinal sectional side view of a main part of a rack and pinion type steering device according to the present invention.

FIG. 3 is a cross-sectional view of the entire rack and pinion type steering device according to the present invention.

FIG. 4 is a front view of a rack shaft according to the present invention.

FIG. 5 shows a rack shaft according to the present invention, in which (a)
4 is an enlarged cross-sectional view taken along line XX of FIG. 4, and FIG.
The enlarged sectional view of the line, (c) is an enlarged bottom view, and (d) is an enlarged plan view.

FIG. 6 is a bottom view of only the shaft main body of the rack shaft according to the present invention.

7A and 7B show a conventional example, in which FIG.
(B) is a longitudinal side view.

[Explanation of symbols]

 2 Rack Shaft 21 Concave Section 3 Rack Housing 4 Cylindrical Body 4a Splitting Section 41 Cylindrical Body 42 Connecting Section 43 Restraining Section

Claims (3)

[Claims] 1. A rack housing for accommodating a rack shaft that moves in the left-right direction of a vehicle body in conjunction with a pinion shaft that rotates in accordance with a steering operation, and a load acting on the rack shaft from a tie rod attached to the rack shaft. In the rack and pinion type steering device, wherein a cylindrical body that receives the inner surface of the rack housing is provided on the rack shaft, the cylindrical body includes a cylindrical body provided with a split portion in an axial length direction, and a periphery of the cylindrical body. A rack-and-pinion type steering device, comprising: a connecting portion that connects both ends in the direction across the split portion, wherein the rack is formed on the rack shaft using the rack shaft as a core material. 2. A recess is provided at a position corresponding to the cylinder on the rack shaft, and a restricting portion is formed in the cylinder to enter the recess and restrict movement of the cylinder. The rack and pinion type steering device according to claim 1. 3. A rack shaft, comprising: a cylindrical body provided on an outer surface of a shaft main body to which a steering tie rod is attached, for receiving a load acting from the tie rod on an inner surface of a rack housing in which the shaft main body is housed. The tubular body includes a tubular body provided with a split portion over the entire length and a connecting portion that connects the circumferential ends of the tubular body across the split portion,
A rack shaft, wherein the shaft body is formed on the shaft body using the shaft body as a core material.