JPH11165645A - Jointing structure, jointing method and jointing device for torsion bar in torque sensor for power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the sensitivity of a sensor and prevent degradation of steering feeling by improving jointing strength in the drawing direction of a torsion bar, in the jointing structure, jointing method, and jointing device of the torsion bar in a torque sensor for power steering device. SOLUTION: This jointing structure of a torsion bar 5 in a torque sensor for power steering device is so constructed that a press-in part to the press-in hole 7 of the output shaft 4 of the torsion bar 5 may be formed into a straight serration part 5a, a rear end part 5b may be pressed-in deeper than the formation surface 10 of the press-in hole 7 when the serration 5a is pressed in the press-in hole 7 of the output shaft 4, the surrounding part of the opening part of the press-in hole 7 may be caulked, and a wall 23 at the caulked part may be built over the rear end part 5b of the serration part 5a, in the jointing structure of the torsion bar 5 in the torque sensor for power steering device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coupling structure, a coupling method, and a coupling device for a torsion bar in a torque sensor of a power steering device, and more particularly, to improving the coupling strength in a direction in which the torsion bar is pulled out to maintain sensor sensitivity. Further, the present invention relates to a coupling structure, a coupling method, and a coupling device of a torsion bar in a torque sensor of a power steering device that prevent deterioration of a steering feeling.

[0002]

2. Description of the Related Art In a torque sensor of a power steering device such as an electric power steering device, when a torsion bar is displaced in a pulling direction, a relative torsion between an input shaft and an output shaft of a steering force is generated. Since the sensor cannot accurately detect the amount, the steering assist force cannot be obtained properly, the steering feeling deteriorates, and in the worst case, the function of the power steering system is lost. It is necessary to increase the bonding strength of

Conventionally, in a power steering device,
An input shaft interlocked to the steering wheel and an output shaft (pinion shaft) interlocked to the wheel are connected by a torsion bar, and when the steering wheel is rotated left and right, the input shaft is Since relative torsion occurs between the output shaft and the output shaft, the amount of torsion is detected by a torque sensor, and a steering assist force corresponding to the amount of torsion is transmitted to the output side.

At this time, when connecting the torsion bar to the pinion shaft which is the output shaft, as shown in FIG. 11, the large-diameter end portion 05a of the serration-processed torsion bar 05 is Then, until the surface of the end portion 05b is flush with the surface around the opening of the press-fitting hole 07 formed at one end of the pinion shaft 04 (the surface on which the press-fitting hole 07 is formed) 010,
The connection was made by press-fitting into the press-fitting hole 07.

For this reason, the torsion bar 05 and the pinion shaft
The strength of the connection with 04 is based only on the press-fitting into the press-fitting hole 07 of the pinion shaft 04 at the large-diameter end 05a of the torsion bar 05 that has been subjected to serration processing. Even if there is, when relative torsion occurs between the input shaft (not shown) and the output shaft (pinion shaft) 04 as described above, the torsion bar 05 receives a compressive force in the axial direction, and The compressive force may cause an abnormal situation in which the large-diameter end portion 05a is pulled out of the press-fitting hole 07 of the pinion shaft 04, and it has been necessary to take a double fail-safe.

When the large-diameter end portion 05a of the torsion bar 05 is withdrawn even slightly from the press-fitting hole 07 of the pinion shaft 04, the neutral position of the core of the torque sensor goes wrong, so that the torque sensor moves between the input shaft and the output shaft 04. The relative amount of torsion cannot be accurately detected, so that an appropriate steering assist force cannot be obtained, and the steering feeling deteriorates. In the worst case, the function of the power steering system may be lost. Was.

In order to prevent the large-diameter end portion of the serration-processed torsion bar from being pulled out from the press-fit hole of the pinion shaft, there is one in which the periphery of the opening of the press-fit hole of the pinion shaft is caulked ( See Japanese Utility Model Publication No. 7-381).

However, in this case, the large-diameter end of the torsion bar on which the serration processing is performed is
Since the taper tapered in the direction of the front end face is provided, there is a disadvantage that the coupling strength of the torsion bar to the pinion shaft is not sufficient with respect to the load in the pull-out direction.

The invention of the present application improves the coupling strength of the torsion bar in the pulling-out direction, maintains the sensitivity of the torque sensor normally, thereby obtains an appropriate steering assist force, deteriorates the steering feeling, and reduces the power steering. An object of the present invention is to provide a coupling structure, a coupling method, and a coupling device of a torsion bar in a torque sensor of a power steering device, which can eliminate the possibility of losing the function of the system.

[0010]

The invention of the present application relates to a coupling structure, a coupling method and a coupling device of a torsion bar in a power steering device which solves the above-mentioned problems, and is described in claim 1. According to the invention, in the coupling structure of the torsion bar in the torque sensor of the power steering device, a press-fitting portion of the output shaft of the torsion bar into the press-fitting hole is a straight serration portion, and the serration portion is formed by press fitting of the output shaft. When pressed into the hole, the rear end is pressed deeper than the surface on which the press-fit hole is formed, and the periphery of the opening of the press-fit hole of the output shaft is caulked, and the flesh of the caulked portion is formed. Is raised on the rear end of the serration portion in the torque sensor of the power steering device. It is a binding structure of Shonba.

Since the invention described in claim 1 is configured as described above, the coupling of the torsion bar to the output shaft (pinion shaft) is performed by connecting the press-fitting portion of the torsion bar, which is a serration portion, to the output shaft. Bonding force due to press-fitting into the press-fitting hole, and jointing force due to the fact that the flesh of the caulked portion around the opening of the press-fitting hole of the output shaft rises above the rear end of the serration portion of the torsion bar. As a result, a double fail-safe coupling structure is obtained, the coupling strength of the torsion bar to the output shaft is improved, and the press-fit portion of the torsion bar is pulled out from the press-fit hole of the output shaft. Disappears. As a result, the sensitivity of the torque sensor is normally maintained, an appropriate steering assist force is obtained, and it is possible to eliminate the risk of deterioration of the steering feeling and loss of the function of the power steering system.

Further, the invention described in claim 2 is:
In the method of coupling a torsion bar in a torque sensor of a power steering device, a press-fitting portion of the torsion bar into a press-fitting hole of an output shaft is a straight serration, and the serration is press-fitted into a press-fitting hole of the output shaft. When the rear end portion is pressed deeper than the surface where the press-fitting hole is formed, the periphery of the opening of the press-fitting hole of the output shaft is caulked, and the flesh of the caulked portion is the rear end of the serration portion. A method of coupling a torsion bar in a torque sensor of a power steering device, wherein the torsion bar is coupled to the output shaft so as to swell over a portion.

According to the second aspect of the present invention, since the torsion bar is connected to the output shaft, the press-fit portion of the torsion bar, which is a serration portion, is pressed into the press-fit hole of the output shaft. And the binding power of
The flesh of the caulked part around the opening of the press-fit hole of the output shaft is
An effect similar to the above-mentioned effect achieved by the invention according to claim 1, wherein the effect is obtained based on the binding force by being raised above the rear end of the serration portion of the torsion bar. Can be played.

[0014] Further, the invention described in claim 3 is:
In the coupling device of the torsion bar in the torque sensor of the power steering device, the press-fitting portion of the torsion bar into the press-fitting hole of the output shaft is a straight serration portion, and the serration portion is formed in the press-fitting hole of the output shaft. The rear end portion is pressed deeper than the surface on which the press-fitting hole is formed, and the assembly of the press-fitted torsion bar and the output shaft, and caulking around the opening of the press-fitting hole of the output shaft, A cylindrical caulking jig for allowing the meat of the caulked portion to rise above the rear end of the serration portion, and a torsion bar of the assembly is passed through the cylinder of the caulking jig, and the caulking is performed. With the tip of the jig abutting around the opening of the press-fit hole of the output shaft in the assembly, and in the state where the caulking jig and the assembly are coaxial Holding means for holding the caulking jig and the assembly; and press means for pressing an end of the output shaft of the assembly opposite to the side where the torsion bar is press-fitted. And a torsion bar coupling device in the torque sensor of the power steering device.

According to the third aspect of the present invention, since it is configured as described above, the assembly of the torsion bar and the output shaft and the periphery of the opening of the press-fitting hole of the output shaft are caulked. A cylindrical caulking jig that causes the flesh of the caught portion to rise above the rear end of the serration portion; holding means for holding the caulking jig and the assembly in coaxial abutting relationship; Press means for pressurizing the end opposite to the side where the torsion bar is press-fitted, and the assembly further includes a press-fitting portion into a press-fitting hole of an output shaft of the torsion bar,
A straight serration is formed, and the serration is press-fitted into the press-fitting hole such that the rear end thereof is deeper than the surface on which the press-fitting hole is formed. When the end opposite to the side where the bar is pressed is pressed, the periphery of the opening of the press-fit hole of the output shaft is easily caulked, and the flesh of the caulked portion is the rear end of the serration portion of the torsion bar. It can be raised on the top.

[0016] Thus, the coupling of the torsion bar to the output shaft depends on the coupling force by press-fitting the press-fit portion of the torsion bar, which is a serration portion, into the press-fit hole of the output shaft, and around the opening of the press-fit hole of the output shaft. The joint structure obtained based on the joint force obtained by making the meat of the crimped portion rise above the rear end portion of the serration portion of the torsion bar can be easily obtained, and the claim 1 can be easily obtained. The same effect as the above-described effect of the invention can be achieved.

Further, the holding means passes the torsion bar of the assembly into the cylinder of the caulking jig so that the tip of the caulking jig abuts around the opening of the press-fitting hole of the output shaft. Since the caulking jig and the assembly can be held in a state where the jig and the assembly are coaxial, press working can be performed safely and accurately.

According to a fourth aspect of the present invention, the caulking jig is constituted by a stepped cylindrical body having a large diameter portion and a small diameter portion. The end of the small diameter portion of the body is tapered, and a plurality of claws are provided at its tip in the circumferential direction.Therefore, the number of caulking portions necessary for coupling the torsion bar to the output shaft is formed on the output shaft. It can be effectively and easily formed around the opening of the press-fitting hole. Further, the caulking jig after the caulking can be easily pulled out.

Further, by configuring the invention according to the fourth aspect as described in the fifth aspect, the angle of the claw is set to 2 or the like so that the angle between both sides in the circumferential direction is 90 °. Since the taper is symmetrical with respect to the parting surface, it has good bite into the machined surface, and can be easily caulked around the opening of the press-fit hole of the output shaft.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claims 1 to 5 of the present application shown in FIGS. 1 to 10 will be described below. FIG. 1 is a partial longitudinal side view of a portion around a torque sensor of an electric power steering device to which a torsion bar coupling structure according to the present embodiment is applied, FIG. 2 is a longitudinal side view of the same portion, FIG.
2 is a partially enlarged view of FIG. 2, FIG. 4 is a partially enlarged view of FIG. 3, FIG. 5 is a schematic overall configuration diagram of a coupling device for manufacturing a torsion bar coupling structure in the present embodiment, and FIG. , FIG. 7 is a vertical side view of the caulking jig, FIG. 8 is a right side view of FIG. 7, and FIG. 9 is a partial enlarged view of FIG. FIG. 10 is a partially enlarged view of FIG. 9 showing a part of the cross section on the processing surface side.

In FIGS. 1 and 2, a torque sensor 1 of an electric power steering system has a steering wheel (not shown) connected to an upper end of an input shaft 3 in the drawing, and the input shaft 3 is connected to a torsion bar 5. Through a pinion shaft 4 serving as an output shaft.

One end of the torsion bar 5 is connected to one end of the input shaft 3 by a pin 6, and the other end is press-fitted into a press-fit hole 7 formed at one end of the pinion shaft 4.
You are joined there. The pinion of the pinion shaft 4 meshes with a rack (not shown), and is further connected to the wheels via a link mechanism.

The other end of the input shaft 3 is inserted into a fitting hole 8 formed at one end of the pinion shaft 4 and is rotatably held therein. 2
It is rotatably supported by bearings 9 in the upper part of the inside of the sensor housing 2 made of the divided body. The bottom surface 10 of the fitting hole 8 forms a surface on which the press-fit hole 7 is formed.

One end of the pinion shaft 4 is rotatably positioned in the axial direction and supported by a bearing 11 below the inside of the sensor housing 2 in the drawing. Note that the bearing 11 is pressed by a holder 12, and the holder 12 is pressed and fixed by an internal circlip 13.

In FIG. 2, a pair of left and right pins 14 are inserted through one end of the pinion shaft 4 through the wall (cylindrical wall) 4a of the fitting hole 8. Are fitted into a pair of left and right vertical grooves 16 formed in the lower part of the core 15 of the torque sensor 1, whereby the core 15 rotates integrally with the pinion shaft 4 and
Is movable in the axial direction.

The upper part of the core 15 is fitted to the input shaft 3 and the lower part thereof is fitted to the pinion shaft 4 inside the sensor housing 2. And rotate integrally with the pinion shaft 4,
The pinion shaft 4 is movable in the axial direction.

The upper part of the core 15 passes through a cylindrical wall of the input shaft 3 through a pair of front and rear spiral grooves 17 (the rear spiral groove 17 is not shown) formed in the reduced diameter cylindrical part. A pair of attached front and rear slider pins 18 (rear slider pins 18 are not shown) are engaged, whereby the pinion shaft 4 is fixed, and the core 15 is movable only in the axial direction of the pinion shaft 4. When the input shaft 3 rotates, the slider pin 18 pushes up or down the inclined wall of the spiral groove 17 so that the core 15 can move in the axial direction according to the rotation amount of the input shaft 3. Has been.

In the above case, the amount of rotation of the input shaft 3 with the pinion shaft 4 fixed is equivalent to the relative amount of rotation of the input shaft 3 with respect to the pinion shaft 4.
When the input shaft 3 is rotated by the steering wheel, the pinion shaft 4 connected to the input shaft 3 via the torsion bar 5 causes the pinion shaft 4 to move due to the steering resistance on the wheel side. Cannot follow the rotation of the torsion bar 5, and the rotation is delayed from this, and the torsion bar 5 has an amount corresponding to the amount of twist.

As described above, the amount of torsion of the torsion bar 5, that is, the input shaft 3 is controlled by the amount of axial movement of the core 15.
Since a relative rotation amount difference between the two based on the torque acting between the pinion shaft 4 and the pinion shaft 4 can be detected, a steering assist force corresponding to the axial movement amount is applied to the output side after the pinion shaft 4. Thus, the amount of twist of the torsion bar 5 can be eliminated, and the wheels can be steered, so that a light feeling of steering can be obtained.

The amount of movement of the core 15 in the axial direction is determined by the non-magnetic metal ring 19 attached to the core body 15a (made of a hard plastic material) of the core 15.
2, the upper and lower coils 20a embedded in FIG.
These coils caused by passing the magnetic flux created by 20b
By detecting a change in inductance of 20a and 20b, it can be obtained along with the direction of movement.

When the core 15 is in its neutral state, its axial center is located at the boundary between the coil 20a and the coil 20b. Reference numeral 21 denotes a coil spring, which abuts against the lower surface of a ring-shaped spring spacer 22 and constantly urges the core 15 upward through the spring spacer 22 so that the neutral position does not fluctuate. ,
The input shaft 3 and the pinion shaft 4 are supported so that they can be constantly displaced by following a change in torque acting between the input shaft 3 and the pinion shaft 4.

When the torsion bar 5 is twisted due to a relative rotation difference between the input shaft 3 and the pinion shaft 4, it receives a compressive force in the axial direction. Due to this compressive force, the torsion bar 5 whose one end is connected to one end of the input shaft 3 by the pin 6 has a press-fit portion 5a press-fitted into the press-fit hole 7 of the pinion shaft 4 at the other end. It receives force in the direction of being pulled out from.

When the press-fitting portion 5a of the torsion bar 5 is slightly pulled out from the press-fitting hole 7 by this force, the input shaft 3 is displaced slightly upward integrally with the torsion bar 5, so that the input shaft 3 and the slider pin 18 are displaced. Then, the neutral position of the core 15 engaged with the core 15 is displaced via the spiral groove 17, and the amount of twist of the torsion bar 5, that is, the relative rotation difference between the input shaft 3 and the pinion shaft 4 can be accurately detected. Disappears. As a result, an appropriate steering assist force according to the steering torque cannot be obtained, so that the steering feeling deteriorates.

In this embodiment, the torsion bar 5
In order to prevent the press-fitting portion 5a at the other end of the pinion shaft 5 from being pulled out from the press-fitting hole 7 of the pinion shaft 4, the following structure is adopted. As shown in FIGS. 2 and 3, the press-fit portion 5a at the other end of the torsion bar 5 has a larger diameter than the central portion thereof and is formed in a straight shape without taper. The large-diameter portion is a serration portion, and serration processing is performed except for a small length at both ends.

The torsion bar 5 thus obtained
The serration part (press-fit part) 5a at the other end of the pinion shaft 4
When press-fitted into the press-fitting hole 7, the serration is crushed, and a firm connection between the torsion bar 5 and the pinion shaft 4 is obtained. Thereby, the serration portion 5a at the other end of the torsion bar 5 can be prevented from being pulled out from the press-fit hole 7 of the pinion shaft 4 to some extent.

When the serration portion 5a is press-fitted into the press-fitting hole 7 of the pinion shaft 4, its rear end 5b is made deeper than the surface 10 where the press-fitting hole 7 is formed (the bottom surface of the fitting hole 8). ing. As shown in detail in FIG. 4, around the opening of the press-fitting hole 7, a surface on which the press-fitting hole 7 is formed is formed.
10 is caulked and the caulked portion of meat 23
Is the serration part 5 which is deeply pressed as described above.
Above the rear end 5b of a, it rises over a slight width a.

The raised portion does not need to be provided over the entire circumference, and is appropriately spaced in the circumferential direction.
It may be provided at a plurality of locations. In the present embodiment, 4
A raised portion having a circumferential width of several mm to 10 mm is formed at each location. 24 is a nail of a caulking jig 25 described later
25d is the remains after swaging.

As described above, the flesh 23 of the crimped portion around the opening of the press-fitting hole 7 is raised on the rear end portion 5b of the serration portion 5a, so that the torsion bar 5 and the pinion shaft 4 are raised. Is obtained. Thus, the serration portion 5a at the other end of the torsion bar 5 can be reliably prevented from being pulled out from the press-fit hole 7 of the pinion shaft 4.

Next, the periphery of the opening of the press-fitting hole 7 of the pinion shaft 4 is swaged, and the flesh 23 of the swaged portion is raised on the rear end 5b of the serration 5a at the other end of the torsion bar 5. The method and apparatus for doing so will be described with reference to FIGS.

First, the serration portion 5a at the other end of the torsion bar 5 is inserted into the press-fitting hole 7 of the pinion shaft 4, and the rear end 5b of the serration portion 5a is formed from the surface 10 on which the press-fitting hole 7 is formed (the bottom surface of the fitting hole 8). Press down and assemble it so that it is located deep (see FIGS. 3 and 6). The pinion shaft 4 has a bearing
11 is fitted in advance.

Next, in the press machine 30, the caulking jig 25 is inserted into the large-diameter step portion 33a inside the work / jig holding cylinder 33 held by the upper and lower shank 32a, 32b on the work holding table 31. It is fitted and fixed from the side of the large diameter portion 25a (see FIGS. 6 and 7). The axial length of the large-diameter step portion 33a of the work / jig holding cylinder 33 is the same as the axial length of the large-diameter portion 25a of the caulking jig 25.

The work / jig holding cylinder 33 is provided with a lower shank 32.
The coil spring 34 is interposed between the upper and lower shanks 32a and 32b. Is held by the work holding table 31 via the.

Next, the cap / guide cylinder 35 is fitted to the upper end of the work / jig holding cylinder 33 and screwed thereto. The cap / guide cylinder 35 has a partition wall 35c having a hole 35d through which a small-diameter portion 25b (see FIGS. 6 and 7) of the caulking jig 25 can be inserted at a substantially central portion in the axial direction. One side partitioned by the partition wall 35c is a cap portion 35a capable of covering the upper end portion of the work / jig holding cylinder 33, and the other side is a serration portion 5a at the other end of the torsion bar 5 described above. Of the pinion shaft 4 in the assembly assembled by press-fitting into the press-fit hole 7 of the pinion shaft 4.
The guide portion 35b is capable of receiving a and guiding the outer peripheral surface thereof.

Therefore, the cap 35a is passed through the small diameter portion 25 of the jig 25 into the hole 35d of the partition wall 35c of the cap / guide cylinder 35, and the cap 35a is connected to one end of the work / jig holding cylinder 33 as described above. And screw it into it. Thus, the surface of the step portion that transitions from the large diameter portion 25a to the small diameter portion 25b of the caulking jig 25 can be held flush with the upper end surface of the work / jig holding cylinder 33. Thus, the caulking jig 25 is set in the work / jig holding cylinder 33.

Then, one end of the torsion bar 5 in the assembly of the torsion bar 5 and the pinion shaft 4 is passed through the cylinder of the jig 25 to hold the work / jig holding cylinder.
While being fitted into the small-diameter step portion 33b of the pinion 33, the inner peripheral surface of the end cylindrical wall 4a of the pinion shaft 4 is caulked along the outer peripheral surface of the small-diameter portion 25b of the jig 25 and the outer peripheral surface of the cylindrical wall 4a. Along the inner peripheral surface of the guide portion 35b of the cap / guide member 35 until the claw portion 25d (see FIG. 7) at the tip of the caulking jig 25 comes into contact with the forming surface 10 of the press-fit hole 7 of the pinion shaft 4. Push in.

The inner peripheral surface of the end cylindrical wall 4a of the pinion shaft 4 and the outer peripheral surface of the small diameter portion 25b of the caulking jig 25 (taper 25c to be described later)
(Excluding the outer peripheral surface portion marked with a circle) has the same diameter, so that the assembly of the torsion bar 5 and the pinion shaft 4 maintains the concentricity with the caulking jig 25 by the above-described procedure. Then, the work / jig holding cylinder 33 holds the work. In this way, a standby state for the swaging operation is established.

In FIG. 6, reference numeral 36 denotes a table, 37 denotes a support frame, and 38 denotes a rail provided for the work holding table 31 to travel on the support frame 37. In addition, a short cylindrical body 32c having the same diameter is provided at the step above the upper shank 32a.
Are stacked so as to guide the lower outer peripheral portion of the cap and guide cylinder 35 and to prevent the rotation thereof.

The caulking jig 25 is, as described above, a large diameter portion 25.
a and a small-diameter portion 25b, and the end of the small-diameter portion 25b has a taper having an inclination angle α at its tip as shown in detail in FIGS. 25c and a plurality (four) of claws 25 in the circumferential direction.
d is provided.

The claw 25d is provided with tapers 25e, 25e symmetrical with respect to a plane bisecting the angle β so that the angle β between the both sides in the circumferential direction is 90 °. The intersection line of both side surfaces is formed so as to be directed in a direction orthogonal to the axis of the caulking jig 25. further,
The claw 25d is tapered at an angle γ so that the inner wall surface extends outward.

Next, the torsion bar 5 and the pinion shaft 4 placed in the standby state for the caulking operation as described above
A crimping operation is performed by applying a pressing force from the end face 4c of the other end 4b of the pinion shaft 4 to the assembly and the caulking jig 25.

In FIG. 5, the press drive mechanism 39 of the press machine 30 may be a mechanical type or a hydraulic type, and the pressing force is applied via a plunger 40 to the pinion shaft 4.
To the end face 4c of the other end 4b. Reference numeral 41 denotes a plunger guide, which is attached to the traversing member 42. The traversing member 42 can move up and down along the left and right columns 43, 43. 44 is a bed.

As described above, the nail 25d of the caulking jig 25
As a result, caulking is performed around the opening of the press-fit hole 7 of the pinion shaft 4, and the flesh 23 of the caulked portion rises above the rear end 5 b of the serration 5 a at the other end of the torsion bar 5. This situation is better illustrated in FIGS. FIG. 4 shows a state where the caulking jig 25 has been removed.

According to the experimental results, in the assembly (combined body) of the torsion bar 5 and the pinion shaft 4 of a given size, all the swaged products satisfy the condition of a pulling load of 600 kgf and a pulling displacement of 0.1 mm or less. I was The minimum load at a displacement of 0.1 mm for the caulked product was 1,300 kgf, whereas the minimum load at a displacement of 0.1 mm for the non-caulked product was 1200 kgf. in this way,
According to the invention of the present application, a remarkable effect was recognized.

Since the first embodiment is configured as described above, the following effects can be obtained. The coupling of the torsion bar 5 to the pinion shaft 4 is performed by press-fitting the press-fitting portion 5a of the torsion bar 5 serving as the serration portion 5a into the press-fitting hole 7 of the pinion shaft 4.
The flesh 23 of the crimped portion around the opening of the press-fitting hole 7 of the pinion shaft 4 is obtained on the basis of the binding force due to being raised above the rear end 5b of the serration portion 5a of the torsion bar 5. As a result, a double fail-safe coupling structure is obtained, the coupling strength of the torsion bar 5 to the pinion shaft 4 is improved, and the press-fit portion 5 of the torsion bar 5 is formed.
a is not removed from the press-fit hole 7 of the pinion shaft 4. As a result, the sensitivity of the torque sensor 1 is normally maintained, an appropriate steering assist force is obtained, and it is possible to eliminate the possibility of deterioration of the steering feeling and loss of the function of the power steering system.

The coupling device for coupling the torsion bar 5 to the pinion shaft 4 includes a coaxial assembly of the assembly of the torsion bar 5 and the pinion shaft 4, the caulking jig 25, and the caulking jig 25 and the assembly. Holding means (work holding table 31, work / jig holding cylinder 33, cap / guide cylindrical body 35) and press means, and the assembly is provided with a pinion of the torsion bar 5. Press-fit hole 7 of shaft 4
The press-fitted portion 5a is formed as a straight serrated portion 5a, and the serrated portion 5a is press-fitted into the press-fit hole 7 so that its rear end 5b is deeper than the surface 10 on which the press-fit hole 7 is formed. Therefore, if the pressing means presses the end face 4c of the other end 4b of the pinion shaft 4, the periphery of the opening of the press-fitting hole 7 of the pinion shaft 4 is easily caulked, and the flesh 23 of the caulked portion is The torsion bar 5 can be raised above the rear end 5b of the serration 5a.

The holding means passes the torsion bar 5 of the assembly into the cylinder of the caulking jig 25, and the claw 25 d at the tip of the caulking jig 25 around the opening of the press-fit hole 7 of the pinion shaft 4. , And in a state where the caulking jig 25 and the assembly are coaxial, the caulking jig 25 and the assembly can be held, so that press working can be performed safely and accurately. . In addition, since the assembly can be easily attached to and detached from the holding means, a large amount of assemblies can be caulked quickly and easily.

Further, the caulking jig 25 is composed of a stepped cylinder having a large diameter portion 25a and a small diameter portion 25b, and the end of the small diameter portion 25b of the stepped cylinder is tapered 25c. At its tip, a plurality of claws 25d are provided in the circumferential direction, so that caulking portions necessary for coupling the torsion bar 5 to the pinion shaft 4 are formed around the opening of the press-fit hole 7 of the pinion shaft 4. Effectively and easily, the caulking jig 25 after the caulking can be easily pulled out.

Further, the claw 25d is provided with tapers 25e, 25e symmetrical with respect to a plane bisecting the angle so that an angle between both sides in the circumferential direction is 90 °. It has good bite into the surface, and can be easily caulked around the opening of the press-fit hole 7 of the pinion shaft 4.

In this embodiment, the torque sensor 1 of the power steering device is a torque sensor of the electric power steering device, but is not limited to this.
It goes without saying that the torque sensor of the hydraulic power steering device may be used.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional side view of a portion around a torque sensor of an electric power steering apparatus to which a torsion bar coupling structure is applied according to an embodiment of the present invention described in claims 1 to 5 of the present application; It is.

FIG. 2 is a vertical sectional side view of the same part.

FIG. 3 is a partially enlarged view of FIG. 2;

FIG. 4 is a partially enlarged view of FIG. 3;

FIG. 5 is a schematic overall configuration diagram of a coupling device for manufacturing the torsion bar coupling structure in the embodiment of FIG. 1;

6 is a schematic vertical sectional side view of a holding portion of a work and a caulking jig in FIG. 5;

FIG. 7 is a longitudinal sectional side view of the caulking jig in the embodiment of FIG. 1;

FIG. 8 is a right side view of FIG. 7;

9 is a diagram showing a partially enlarged view of FIG. 7 together with a part of a cross section on a processing surface side.

FIG. 10 is a partially enlarged view of FIG. 9;

FIG. 11 is a diagram showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Torque sensor, 2 ... Sensor housing, 3 ... Input shaft, 4 ... Output shaft (pinion shaft), 4a ... Wall (cylindrical wall),
4b: the other end, 4c: the end face, 5: torsion bar, 5a
... Press-fit part (serration part), 5b ... rear end part, 6 ... Pin, 7 ... Press-fit hole, 8 ... Fit hole, 9 ... Bearing, 10 ... Press-fit hole forming surface (Fit hole bottom surface), 11 ... Bearing, 12… Holder, 13… Internal circlip, 14… Pin, 15… Core, 15a…
Core body, 16 vertical groove, 17 spiral groove, 18 slider pin, 19 non-magnetic ring, 20a, 20b coil, 21 coil spring, 22 spring spacer, 23 meat, 24
… Working trace, 25… Crimping jig, 25a… Large diameter part, 25b… Small diameter part, 25c… Taper, 25d… Claw, 25e… Taper, 30… Press machine, 31… Work holder, 32a, 32b… vertical shank , 32c… short cylinder, 33… work and jig holding cylinder, 33a… large diameter step, 33b… small diameter step, 34… coil spring, 35…
Cap / guide cylinder, 35a cap, 35b guide, 35c partition wall, 35d hole, 36 table, 37 support frame, 38 rail, 39 pressure drive mechanism, 40 plunger, 41 ... plunger guide, 42 ... laid down, 43 ... column, 44 ... bed.

Claims (5)

[Claims] 1. A coupling structure of a torsion bar in a torque sensor of a power steering device, wherein a press-fitting portion of the output shaft of the torsion bar into a press-fitting hole is a straight serration portion, and the serration portion is provided on the output shaft. When press-fitted into the press-fitting hole, the rear end portion is made to press-fit deeper than the surface where the press-fitting hole is formed, and the periphery of the opening of the press-fitting hole of the output shaft is caulked,
The joint structure of a torsion bar in a torque sensor of a power steering device, wherein the flesh of the crimped portion is raised on a rear end of the serration portion. 2. A method of coupling a torsion bar in a torque sensor of a power steering device, wherein a press-fitting portion of the output shaft of the torsion bar into a press-fitting hole is a straight serration portion, and the serration portion is provided on the output shaft. When pressed into the press-fitting hole, the rear end of the press-fitting hole is pressed deeper than the surface where the press-fitting hole is formed, and the periphery of the opening of the press-fitting hole of the output shaft is caulked. A method of coupling a torsion bar in a torque sensor of a power steering device, wherein the torsion bar is coupled to the output shaft so as to rise above a rear end of a serration portion. 3. A coupling device for a torsion bar in a torque sensor of a power steering device, wherein a press-fitting portion of the output shaft of the torsion bar into a press-fitting hole is a straight serration portion, and the serration portion is formed on the output shaft. Into the press-fitting hole, the rear end of which is deeper than the surface on which the press-fitting hole is formed, so that an assembly of the torsion bar and the output shaft, which are press-fitted, and the opening of the press-fitting hole of the output shaft. A caulking jig for caulking the periphery so that the meat of the caulked portion rises above the rear end of the serration portion, and a torsion bar in the assembly is inserted into the cylinder of the caulking jig. Through which the tip of the jig is brought into contact with the periphery of the opening of the press-fit hole of the output shaft in the assembly, and the swaging jig and the assembly are made coaxial. And holding means for holding the caulking jig and the assembly in a folded state; and pressing means for pressing an end of the output shaft of the assembly on a side opposite to a side where the torsion bar is press-fitted. A coupling device for a torsion bar in a torque sensor of a power steering device. 4. The caulking jig is formed of a stepped cylinder having a large diameter portion and a small diameter portion, and the end of the small diameter portion of the stepped cylinder is tapered;
The coupling device for a torsion bar in a torque sensor of a power steering device according to claim 3, wherein a plurality of claws are provided in a tip end thereof in a circumferential direction. 5. The claw is tapered symmetrically with respect to a plane bisecting the angle so that the angle between both sides in the circumferential direction is 90 °. 4
A coupling device for a torsion bar in a torque sensor of the power steering device according to the above.