JP2018002026A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering device that can reduce the number of components and further, can restrain a lubricant from leaking from a housing fitting portion.SOLUTION: A taper 21g is provided at a corner part on an inner peripheral side of a tip part 21d of a reduction gear housing 21. A first extension part 21c is provided at the outer peripheral side of the tip part 21d. A taper 22c is provided at a corner part on an outer peripheral side of a tip part in an insertion part 22d. On the outer peripheral surface of the insertion part 22d, an annular locking part 22a is protruded. On an outer peripheral surface of the locking part 22a, a second extension part 22b is provided. The first extension part 21c is fastened to the second extension part 22b by a bolt 30. In a state where the reduction gear housing 21 is fitted to a sensor housing 22, an annular space S is formed over the whole length in a circumferential direction of the housings, by being surrounded with the outer peripheral surface of the insertion part 22d, an annular surface on the reduction gear housing 21 side of the locking part 22a and the taper 21g.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electric power steering apparatus.

  Conventionally, as described in Patent Document 1, even if a sealing member such as an O-ring is omitted from the fitting portion of the housing that houses the speed reducer, it is possible to prevent the lubricant from leaking out of the housing. There is a simple electric power steering device.

  The housing is formed by fitting a worm housing and a sensor housing together. Lubricants for smooth meshing are applied to the teeth of the worm and worm wheel that are components of the reduction gear. When the worm wheel rotates, the lubricant travels along the side surface of the worm wheel and the inner surface of the sensor housing, reaches the mating portion of the worm housing and the sensor housing, and the lubricant may leak from the mating portion. Therefore, the worm wheel is provided with a return member. The return member has a cylindrical tube portion standing on the side surface of the worm wheel on the worm housing opening side, and an umbrella portion extending radially outward from the periphery of the tube portion. Lubricant that travels along the side surface of the worm housing and the inner surface of the sensor housing is blocked by the umbrella.

JP2014-2331260

  However, according to the electric power steering device described in Patent Document 1, it is possible to omit a sealing member such as an O-ring from the fitting portion of the housing, but a return member is newly provided. .

  The objective of this invention is providing the electric power steering apparatus which can suppress the leakage of the lubricant from a housing fitting part, after reducing a number of parts.

  An electric power steering apparatus that can achieve the above object includes a motor that generates assist force, a reduction gear that reduces the rotation of the motor and transmits the reduced rotation to the steering mechanism, and a housing that houses the reduction gear. It is assumed that The housing has a cylindrical bottomed first housing that houses a reduction gear therein, and a cylindrical second fitted in the axial direction so as to close the opening of the first housing. A peripheral edge of one of the first housing and the second housing is fitted into the other opening, and the first housing and An annular space is provided in a part of a region where the second housings are in contact with each other over the entire length in the circumferential direction, and the first housing and the second housing are part of each other. It is fastened with bolts in the axial direction.

  The reduction gear may be coated with a lubricant that facilitates its drive. In that case, there is a concern about the following in a state where the first housing and the second housing are fitted. Due to manufacturing tolerances, for example, the outer diameter of the opening periphery of one of the first housing and the second housing and the inner diameter of the other opening vary, or the first housing and the second housing The mounting position of the two housings may be shifted. For this reason, when the peripheral edge of one of the first housing and the second housing is fitted into the other opening, a minute gap is formed along a region where they contact each other. There is a fear. By forming the minute gap, there is a possibility that the lubricant is transmitted from the inside of the housing through the minute gap by capillary action and leaks to the outside of the housing.

  In that respect, in the configuration described above, an annular space is provided over the entire length in the circumferential direction of the housing in a part of the region where the first housing and the second housing contact each other as a lubricant leakage path. . Therefore, even if the lubricant is transmitted through a minute space, the lubricant can be dammed in the annular space. In addition, a part of the first housing and the second housing are fastened with bolts in their axial directions. Therefore, since the first housing and the second housing can be brought into close contact with each other in the mounting direction, formation of a minute space can be suppressed. Therefore, the leakage of the lubricant from the fitting portion of the housing can be suppressed while reducing the number of parts.

  Either one of the first housing and the second housing has an insertion portion fitted into the other opening, and the insertion portion is fitted into the other opening. At least the other opening portion among the outer peripheral corner portion at the distal end of the insertion portion and the inner corner portion at the peripheral edge portion of the other opening portion. A taper is provided at an inner corner portion of the peripheral edge portion of the insertion portion, and is surrounded by the taper provided at the inner corner portion of the outer peripheral surface of the insertion portion, the annular surface, and the peripheral edge portion of the other opening portion. It is preferable that the space is formed.

  According to the above configuration, by providing a taper at the outer peripheral corner portion at the distal end of the insertion portion and the inner corner portion at the peripheral edge portion of the other opening portion, either one of the first housing and the second housing is provided. The centering of the housings is improved when the peripheral edge of the opening is fitted to one of the other openings. Therefore, the fitting of the first housing and the second housing becomes smooth.

  In addition, by providing a taper at the inner corner of the peripheral edge of at least the other opening, when the first housing and the second housing are fitted, the insertion portion, the annular surface, and the other opening An annular space can be formed by being surrounded by a taper provided at an inner corner of the peripheral edge. That is, since it is only necessary to provide a taper at the inner corner of the peripheral edge of the other opening, the structure of the housing is not complicated.

It is preferable that the surface roughness of the surfaces of the first housing and the second housing that contact each other in the region is different.
According to the above configuration, even if a minute gap is formed in a region where the housings are in contact with each other, the gap is a minute space with a labyrinth shape by combining fine irregularities different in height and interval. It becomes. That is, the transmission path of the lubricant becomes longer, and the loss of the lubricant pressure becomes larger. Therefore, even if the lubricant is transmitted through a minute gap, the leakage of the lubricant from the housing fitting portion can be further suppressed.

It is preferable that a spiral groove is formed on the outer peripheral surface of the insertion portion or the inner peripheral surface of the other opening.
According to the above configuration, the outer peripheral surface of the insertion portion is in contact with the inner peripheral surface of the other opening in a state where the opening peripheral edge of one housing is fitted into the opening of the other housing. Therefore, a continuous spiral path is formed over the entire length in the axial direction of the insertion portion in a portion surrounded by the inner peripheral surface of the other opening and the outer peripheral surface of the insertion portion. With such a configuration, even if the lubricant has entered between the inner peripheral surface of the other opening and the outer peripheral surface of the insertion portion, the lubricant travels along a spiral path. That is, the lubricant transmission path can be made longer than in the case where no spiral groove is provided on the outer peripheral surface of the insertion portion or the inner peripheral surface of the other opening. Therefore, it is possible to further suppress the lubricant from leaking from the inside of the housing to the outside of the housing.

  According to the electric power steering apparatus of the present invention, the leakage of the lubricant from the housing fitting portion can be suppressed while reducing the number of parts.

1 is a schematic diagram of an electric power steering device according to a first embodiment. FIG. 3 is a partial cross-sectional view of the speed reduction mechanism according to the first embodiment. Sectional drawing which expanded the housing fitting part in 1st Embodiment. Sectional drawing which expanded the housing fitting part in 2nd Embodiment. Sectional drawing which expanded the housing fitting part in 3rd Embodiment. Sectional drawing which expanded the housing fitting part in other embodiment.

<First Embodiment>
Hereinafter, a first embodiment of an electric power steering apparatus (hereinafter referred to as “EPS”) of the present invention will be described.

  As shown in FIG. 1, the EPS 1 includes a steering mechanism 2 that steers the steered wheels 15 based on a user's operation of the steering wheel 10, and an EPS actuator 3 that assists the user's steering operation.

  The steering mechanism 2 includes a steering wheel 10 and a steering shaft 11 that rotates integrally with the steering wheel 10. The steering shaft 11 includes a column shaft 11a connected to the steering wheel 10, an intermediate shaft 11b connected to the lower end portion of the column shaft 11a, and a pinion shaft 11c connected to the lower end portion of the intermediate shaft 11b. doing. A lower end portion of the pinion shaft 11 c is connected to a rack shaft 12 as a steered shaft via a rack and pinion mechanism 13. Therefore, the rotational movement of the steering shaft 11 is caused in the axial direction of the rack shaft 12 via the rack and pinion mechanism 13 composed of a portion provided with pinion teeth on the pinion shaft 11 c and a portion provided with rack teeth on the rack shaft 12 ( It is converted into a reciprocating linear motion in the left-right direction in FIG. The reciprocating linear motion is transmitted to the left and right steered wheels 15 via the tie rods 14 respectively connected to both ends of the rack shaft 12, whereby the steered angle of the steered wheels 15 changes.

  The EPS actuator 3 is provided on the column shaft 11a. The EPS actuator 3 has a motor 50 and a speed reducer 40. The rotation of the motor 50 is decelerated by the speed reducer 40, and this decelerated rotation is transmitted to the column shaft 11a, thereby assisting the steering operation.

Next, the speed reducer 40 will be described.
As shown in FIG. 2, the speed reducer 40 is accommodated in the housing 20 through which the column shaft 11a penetrates in the axial direction. The column shaft 11a is rotatably supported with respect to the housing 20 via bearings 23, 24, and 25. The speed reducer 40 has a worm wheel (not shown) provided on the rotating shaft of the motor 50 and the worm wheel 26 fixed to the outer peripheral surface of the column shaft 11 a in the internal space of the housing 20. A worm gear 26 a is provided on the outer peripheral surface of the worm wheel 26. The worm gear 26a and the worm mesh with each other. Lubricant F is applied between the worm gear 26 a and the worm provided on the rotating shaft of the motor 50.

  The column shaft 11a has an input shaft 11d, an output shaft 11e, and a torsion bar 11f. A steering wheel 10 is fixed to the upper end portion of the input shaft 11d. An intermediate shaft 11b is connected to the lower end of the output shaft 11e. The input shaft 11d and the output shaft 11e are provided so as to be relatively rotatable via a torsion bar 11f. The torsion bar 11f is twisted according to the difference between the torque of the input shaft 11d and the torque of the output shaft 11e.

  A torque sensor 27 is accommodated in the housing 20. The torque sensor 27 includes a magnet unit 27a, a magnetic yoke unit 27b, a pair of magnetism collecting rings 27c, and a magnetic sensor (not shown). The magnetic flux of the magnet unit 27a is transmitted to the pair of magnetism collecting rings 27c via the magnetic yoke unit 27b according to the twist of the torsion bar 11f. The magnetic sensor generates a voltage signal corresponding to the magnetic flux of the pair of magnetism collecting rings 27c. The control device of the EPS 1 calculates a steering torque based on the voltage signal generated by the magnetic sensor, and controls power supply to the motor 50 according to the calculated steering torque.

  The housing 20 includes a speed reducer housing 21 as a first housing and a sensor housing 22 as a second housing. The reduction gear housing 21 and the sensor housing 22 are fitted along the axial direction of the column shaft 11a, and are fastened by two bolts 30 in the axial direction after fitting.

  The reduction gear housing 21 has a bottomed cylindrical shape extending along the axis of the column shaft 11a. A worm wheel 26 is accommodated in the reduction gear housing 21. The reduction gear housing 21 is erected along the axial direction of the column shaft 11a from the outer edge of the bottom wall 21a and the bottom wall 21a having a diameter larger than the outer diameter of the worm wheel 26, and surrounds the outer periphery of the worm wheel 26. And the two first extending portions 21c provided at the end portion 21d side portion of the outer peripheral surface of the peripheral wall 21b.

  The two first extending portions 21 c are provided at positions opposite to each other in the radial direction of the speed reducer housing 21. The two first extending portions 21c are provided with bolt insertion holes through which the bolts 30 are inserted.

  A taper 21g is provided over the entire circumference of the corner on the inner peripheral surface side of the tip 21d of the peripheral wall 21b. The taper 21g increases in diameter toward the opposite side of the bottom wall 21a in the axial direction of the reduction gear housing 21.

  The sensor housing 22 has a cylindrical shape. A torque sensor 27 is accommodated in the sensor housing 22. An annular locking portion 22 a is provided on the outer peripheral surface of the sensor housing 22 over the entire circumferential direction. Two second extending portions 22b are provided on the outer peripheral surface of the locking portion 22a. These two second extending portions 22 b are located on the opposite sides in the radial direction of the sensor housing 22. The two second extending portions 22 b are provided at positions corresponding to the two first extending portions 21 c of the reduction gear housing 21. The two second extending portions 22b each have a bolt insertion hole through which the bolt 30 is inserted. The sensor housing 22 has an outer diameter corresponding to the inner diameter of the peripheral wall 21 b of the reduction gear housing 21. The sensor housing 22 is fitted in the reduction gear housing 21. In the sensor housing 22, a taper 22 c is provided at a corner portion on the outer peripheral surface side of the distal end portion of the insertion portion 22 d which is a portion fitted to the speed reducer housing 21. The taper 22c decreases in diameter in the axial direction of the sensor housing 22 toward the distal end of the insertion portion 22d.

  The locking portion 22a is in contact with the distal end portion 21d of the peripheral wall 21b of the reduction gear housing 21 in the axial direction of the column shaft 11a. Further, the two second extending portions 22 b and the two first extending portions 21 c of the speed reducer housing 21 are in contact with each other in the axial direction of the housing 20. The bolt insertion hole of the second extension portion 22b coincides with the bolt insertion hole of the first extension portion 21c. The first extension portion 21c and the second extension portion 22b are fastened to each other by inserting and tightening the bolt 30 through the bolt insertion hole of the second extension portion 22b and the bolt insertion hole of the first extension portion 21c. .

Next, a method for assembling the housing 20 will be described.
When the sensor housing 22 is fitted to the peripheral wall 21b of the speed reducer housing 21, first, the two first extending portions 21c of the speed reducer housing 21 and the two second extending portions 22b of the sensor housing 22 are matched in the circumferential direction. Let Next, the sensor housing 22 is brought close to the speed reducer housing 21 along the axial direction thereof with the tip end of the input shaft 11 d in the sensor housing 22 facing the opening of the speed reducer housing 21. Then, the insertion portion of the sensor housing 22 is formed in such a manner that the taper 22c provided at the distal end portion of the insertion portion 22d in the sensor housing 22 is guided by the taper 21g provided at the distal end portion 21d of the peripheral wall 21b in the reduction gear housing 21. 22 d gradually fits into the reduction gear housing 21 while sliding with respect to the inner peripheral surface of the peripheral wall 21 b in the reduction gear housing 21. Eventually, the locking portion 22a of the sensor housing 22 comes into contact with the distal end portion 21d of the peripheral wall 21b in the reduction gear housing 21 in the axial direction. At the same time, the two first extending portions 21 c in the speed reducer housing 21 and the two second extending portions 22 b in the sensor housing 22 are in contact with each other in the axial direction. At this timing, the fitting of the sensor housing 22 to the reduction gear housing 21 is completed. Thereafter, the bolt 30 is inserted through the bolt insertion hole of the first extension portion 21c and the bolt insertion hole of the second extension portion 22b, and tightened.

  As shown in FIG. 3, a slight gap is formed between the insertion portion 22 d and the worm wheel 26 in a state where the sensor housing 22 is fitted to the reduction gear housing 21. Further, when the sensor housing 22 is fitted to the speed reducer housing 21, the sensor housing 22 is surrounded by the outer peripheral surface of the insertion portion 22d, the annular surface 22g on the speed reducer housing 21 side of the locking portion 22a, and the taper 21g. The space S is formed.

As described above in detail, according to the EPS 1 according to the present embodiment, the following operations and effects can be obtained.
(1) Due to manufacturing tolerances, for example, the inner diameter of the peripheral wall 21b of the reduction gear housing 21 and the outer diameter of the insertion portion 22d of the sensor housing 22 are varied, or the mounting positions of the reduction gear housing 21 and the sensor housing 22 are displaced. May occur. For this reason, when the reduction gear housing 21 and the sensor housing 22 are fitted to each other, they are in contact with each other (for example, between the inner peripheral surface of the reduction gear housing 21 and the outer peripheral surface of the sensor housing 22 or the peripheral wall 21b. A small gap may be formed along the tip surface of the tip portion 21d and the annular surface 22g of the locking portion 22a on the speed reducer housing 21 side. By forming the minute gap, the lubricant F may be transmitted from the inside of the housing 20 to the outside of the housing 20 through the minute gap due to a capillary phenomenon.

  In that respect, according to the EPS 1 of this example, an annular space is provided in the middle of the boundary between the reduction gear housing 21 and the sensor housing 22, which are leakage paths of the lubricant F, in the circumferential direction of the housing 20. S is provided. Therefore, even if the lubricant F is transmitted through a minute space, the lubricant F can be dammed in the space S.

  Moreover, the 1st extension part 21c of the reduction gear housing 21 and the 2nd extension part 22b of the sensor housing 22 are each fastened with the volt | bolt. That is, the distal end portion 21d of the peripheral wall 21b in the reduction gear housing 21 and the annular locking portion 22a of the sensor housing 22 can be brought into closer contact with each other in the mounting direction. Therefore, it is possible to suppress the formation of a minute gap between the tip portion 21d of the speed reducer housing 21 and the annular locking portion 22a of the sensor housing 22. Therefore, the leakage of the lubricant from the fitting portion of the housing 20 can be suppressed after reducing the number of parts. In addition, since it is only necessary to provide the reduction gear housing 21 with the taper 21g, the configuration is not complicated.

  (2) A taper 22 c is provided at a corner on the outer peripheral surface side of the insertion portion 22 d of the sensor housing 22. A taper 21g is provided at a corner on the inner peripheral surface side of the tip 21d of the reduction gear housing 21. For this reason, when fitting the sensor housing 22 to the reduction gear housing 21, the centering of these housings is improved. Therefore, the work for fitting the reduction gear housing 21 and the sensor housing 22 becomes smooth.

<Second Embodiment>
Hereinafter, a second embodiment of the electric power steering apparatus will be described. This embodiment is different from the first embodiment in the shape of the outer peripheral surface of the insertion portion 22d in the sensor housing 22. For this reason, about the thing corresponding to the structure similar to 1st Embodiment, the same code | symbol is attached | subjected for convenience and detailed description is omitted.

  As shown in FIG. 4, a spiral groove 22 e is provided on the outer peripheral surface of the insertion portion 22 d of the sensor housing 22. Here, the outer diameter of the sensor housing 22 includes the tip of the peak portion 22f of the groove 22e. In a state where the sensor housing 22 is fitted to the reduction gear housing 21, the crest portion 22 f of the groove 22 e in the insertion portion 22 d is in contact with the inner peripheral surface of the peripheral wall 21 b in the reduction gear housing 21. Therefore, a continuous spiral path R is formed over the entire length in the axial direction of the insertion portion 22d in a portion surrounded by the inner peripheral surface of the peripheral wall 21b and the groove 22e of the insertion portion 22d in the reduction gear housing 21. The In addition, you may provide the helical groove | channel 22e in the internal peripheral surface which the surrounding wall 21b in the reduction gear housing 21 makes.

  By adopting such a configuration, even if the lubricant F enters between the inner peripheral surface of the peripheral wall 21b in the reduction gear housing 21 and the outer peripheral surface of the insertion portion 22d in the sensor housing 22, the lubricant F is It travels along the spiral path R. That is, compared with the case where the groove 22e is not provided in the outer peripheral surface of the insertion part 22d of the sensor housing 22, the transmission path of the lubricant F can be lengthened. Therefore, the lubricant F can be further suppressed from leaking from the inside of the housing 20 to the outside of the housing 20.

<Third Embodiment>
Hereinafter, a third embodiment of the electric power steering apparatus will be described. Components corresponding to the same configurations as those in the first embodiment are denoted by the same reference numerals for the sake of convenience, and detailed description thereof is omitted.

  As shown in FIG. 5, in the state where the sensor housing 22 is fitted to the speed reducer housing 21, the surface state of the inner peripheral surface of the peripheral wall 21b and the surface state of the outer peripheral surface of the insertion portion 22d and the tip of the peripheral wall 21b are in contact with each other. The surface state of the tip surface of the portion 21d and the annular surface 22g on the reduction gear housing 21 side in the locking portion 22a are different from each other.

  The surface state is, for example, surface roughness. Here, the surface roughness of the outer peripheral surface of the insertion portion 22d and the annular surface 22g on the reduction gear housing 21 side in the locking portion 22a is the inner peripheral surface of the peripheral wall 21b. It is set to be rougher than the surface roughness of the distal end surface of the distal end portion 21d in the peripheral wall 21b. The surface roughness of the inner peripheral surface of the peripheral wall 21b may be made rougher than the surface roughness of the outer peripheral surface of the insertion portion 22d. Further, the surface roughness of the distal end surface of the distal end portion 21d in the peripheral wall 21b may be made rougher than the surface roughness of the annular surface 22g on the reduction gear housing 21 side in the locking portion 22a.

  By adopting such a configuration, the annular surface on the reduction gear housing 21 side between the outer peripheral surface of the insertion portion 22d and the inner peripheral surface of the peripheral wall 21b, and the front end surface of the front end portion 21d and the locking portion 22a on the peripheral wall 21b. A small labyrinth-shaped space is formed by combining unevenness with fine height, spacing, and the like due to the difference in surface roughness. For this reason, even if the lubricant F enters between the outer peripheral surface of the insertion portion 22d and the inner peripheral surface of the peripheral wall 21b, the route through which the lubricant F is transmitted becomes a maze-like shape. As the transmission path of F becomes longer, the pressure loss of the lubricant F increases. Therefore, the lubricant F can be further suppressed from leaking from the inside of the housing 20 to the outside of the housing 20.

<Other embodiments>
Note that the first to third embodiments may be modified as follows within a technically consistent range.

  In the first to third embodiments, the outer diameter of the insertion portion 22d and the inner diameter of the peripheral wall 21b are constant, but may be as follows, for example. As shown in FIG. 6, the insertion portion 22 d is provided in a truncated cone shape that decreases in diameter in the insertion direction (left direction in the drawing). That is, a taper 22i is provided on the outer peripheral surface of the insertion portion 22d. Along with the provision of the taper 22i, a taper 21h is provided on the inner peripheral surface of the peripheral wall 21b. The inner peripheral surface of the peripheral wall 21b is reduced in diameter toward the insertion direction of the insertion portion 22d. The taper 21h and the taper 22i are in contact with each other over the entire surface of the reduction gear housing 21 and the sensor housing 22 when they are fitted to each other. A taper 21g is provided at a corner between the taper 22i and the front end surface of the peripheral wall 21b (annular surface 22g contacting the locking portion 22a). The inclination angle of the taper 21g with respect to the axis of the speed reducer housing 21 is set larger than the inclination angle of the taper 21h.

  With such a configuration, the reduction gear housing 21 and the sensor housing 22 are brought into closer contact with each other in the axial direction by fastening the first extension portion 21c and the second extension portion 22b with the bolt 30. In addition to the force, the force that closely contacts the housings in the axial direction is decomposed into the force that closely contacts the housing 20 in the radial direction due to the inclination of the taper 21h and the taper 22i. A close force is generated in the radial direction. Therefore, it is possible to further suppress the formation of a minute gap between the reduction gear housing 21 and the sensor housing 22.

  In addition, in the first to third embodiments, the speed reducer housing 21 and the sensor housing 22 are fastened by the two bolts 30, but are not limited thereto. For example, the reduction gear housing 21 and the sensor housing 22 may be fastened with three or more bolts 30. In this case, the same number of first extending portions 21c and second extending portions 22b as the bolts 30 are provided. In addition, it is preferable to arrange | position the 1st extension part 21c and the 2nd extension part 22b at equal intervals in the circumferential direction of the housing 20, respectively. By setting it as such a structure, the reduction gear housing 21 and the sensor housing 22 can be fastened more firmly.

  In the first to third embodiments, the insertion portion 22d of the sensor housing 22 is fitted to the inner peripheral surface of the peripheral wall 21b in the speed reducer housing 21, but this is not restrictive. For example, the reduction gear housing 21 may be fitted to the sensor housing 22. In this case, the configurations of the reduction gear housing 21 and the sensor housing 22 are changed as appropriate. Even if it is such a structure, the effect similar to 1st-3rd embodiment is acquired.

  In the first to third embodiments, the speed reducer housing 21 and the sensor housing 22 are assembled by providing the taper 21g at the corner on the inner peripheral surface side of the tip 21d of the speed reducer housing 21. At this time, the annular space S is formed over the entire circumferential direction of the housing 20, but the present invention is not limited to this. One of the outer peripheral surface of the insertion portion 22d and the inner peripheral surface of the peripheral wall 21b opposed to each other in the radial direction, or one of the front end surface of the peripheral wall 21b and the annular surface 22g on the reduction gear housing 21 side of the locking portion 22a. A groove may be provided over the entire length of the housing 20 in the circumferential direction. By doing so, between the outer peripheral surface of the insertion portion 22d and the inner peripheral surface of the peripheral wall 21b, or between the distal end surface of the peripheral wall 21b and the annular surface 22g of the locking portion 22a on the reduction gear housing 21 side, An annular space S can be provided by being surrounded by opposing surfaces. In this case, the taper 22c can be omitted. By setting it as such a structure, the effect similar to 1st Embodiment-3rd Embodiment is acquired.

  In the first to third embodiments, the reduction gear housing 21 as the first housing that houses the worm wheel 26 and the sensor housing 22 as the second housing that houses the torque sensor 27 are fitted. Although it was trying to match, it is not restricted to this. That is, the speed reducer 40 and the torque sensor 27 may not be housed in the same housing 20 but may be provided at different positions on the column shaft 11a. For example, the configuration of the first housing and the second housing may be adopted in each of the reduction gear housing 21 and the sensor housing 22.

DESCRIPTION OF SYMBOLS 1 ... EPS, 2 ... Steering mechanism, 20 ... Housing, 21 ... Reduction gear housing, 21a ... Bottom wall, 21b ... Peripheral wall, 21c ... 1st extension part, 21g ... Taper, 22 ... Sensor housing, 22a ... Annular engagement Stop part, 22b ... 2nd extension part, 22c ... Taper, 22d ... Insertion part, 22e ... Spiral groove, 22f ... Mountain part, 22g ... Annular surface, 30 ... Bolt, 40 ... Reduction gear, 50 ... Motor, S: An annular space.

Claims (4)

In an electric power steering apparatus comprising: a motor that generates assist force; a speed reducer that decelerates rotation of the motor and transmits the decelerated rotation to a steering mechanism; and a housing that houses the speed reducer.
The housing has a bottomed cylindrical first housing that houses a reduction gear therein;
A cylindrical second housing fitted in the axial direction so as to close the opening of the first housing;
The opening peripheral edge of one of the first housing and the second housing is fitted into the other opening,
In a part of the region where the first housing and the second housing are in contact with each other, an annular space is provided over the entire length in the circumferential direction,
An electric power steering device in which a part of the first housing and the second housing are fastened with bolts in an axial direction. Either one of the first housing and the second housing has an insertion portion fitted into the other opening, and the insertion portion is fitted into the other opening. Having an annular surface that contacts the peripheral edge of the other opening;
Of the corners on the outer peripheral side at the tip of the insertion part and the inner corners in the peripheral part of the other opening, at least the inner corners in the peripheral part of the other opening are tapered. ,
2. The electric motor according to claim 1, wherein the space is formed by being surrounded by an outer peripheral surface of the insertion portion, the annular surface, and the taper provided at an inner corner portion of a peripheral edge portion of the other opening. Power steering device.   3. The electric power steering apparatus according to claim 1, wherein surface roughnesses of surfaces of the first housing and the second housing that contact each other in the region are different from each other.   The electric power steering apparatus according to claim 2, wherein a spiral groove is formed on an outer peripheral surface of the insertion portion or an inner peripheral surface of the other opening.