JP4238612B2 - Electric power steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric power steering device configured to assist steering by transmitting the rotational force of a steering assist motor to a middle of a column shaft that rotates in response to steering.
[0002]
[Prior art]
A steering assisting electric motor (hereinafter simply referred to as a motor) is driven in response to an operation of a steering member (for example, a steering wheel) for steering, and the rotational force of the motor is transmitted to the steering mechanism, thereby the steering mechanism In the electric power steering device that assists the steering performed by the operation of the steering wheel, it is necessary to detect the steering torque applied to the steering wheel in order to be used for the drive control of the steering assist motor. This is performed by a torque sensor arranged in the middle of the column shaft that communicates with the take-up mechanism.
[0003]
This torque sensor divides a column shaft to be detected into a first shaft and a second shaft that are coaxially connected via a small-diameter torsion bar, for example, near the connecting portion of the first and second shafts. Each of the detection rings is fitted and fixed to each other, and a sensor coil is fitted and held in a cylindrical housing that supports the column shaft so as to surround the opposing portion of the detection ring. The sensor coil is connected to a circuit board fixedly supported in a board chamber provided with an opening, and the relative displacement of the first and second shafts caused by the twisting of the torsion bar due to the steering torque is applied to the sensor coil. It is configured to take out through the circuit board as a change in impedance of the sensor coil accompanying an increase or decrease in the magnetic resistance of the magnetic circuit formed at the opposing portion of the detection ring by energization of the coil current. (E.g., see Patent Document 1).
[0004]
Also, as one type of electric power steering device, there is a column assist type electric power steering device configured to transmit the rotation of the steering assist motor to the middle of the column shaft and assist the rotation of the column shaft, In this type of electric power steering device, a gear reduction device such as a worm gear reduction device for transmission from a steering assisting motor to a column shaft is arranged on one side of the torque sensor (for example, a patent) Reference 2).
[0005]
When the torque sensor and the gear reduction device are arranged side by side as described above, generally, as disclosed in Patent Document 2, a gear reduction device housing (gear housing) and a torque sensor housing (sensor housing) are provided. Are assembled separately, and the gear reduction device is assembled around the column shaft that is supported at both ends inside the gear housing. On the other hand, the torque sensor housing side parts (sensor coil, circuit board, etc.) are installed inside the sensor housing. The torque sensor shaft-side parts (detection ring or the like) are respectively assembled to the column shaft protrusion to one side of the gear housing, and the sensor housing is coaxially connected to one side of the gear housing.
[0006]
Since the gear reduction device inside the gear housing is located inside the passenger compartment, it is necessary to reduce the meshing noise between the gears, the backlash between the gears is optimized, and at least the teeth are made of resin. Noise reduction measures are taken to reduce meshing noise, such as using gears.
[0007]
[Patent Document 1]
Japanese Patent Publication No. 7-21433 [Patent Document 2]
Japanese Patent Laid-Open No. 11-248564
[Problems to be solved by the invention]
Now, in the electric power steering apparatus configured as described above, in order to improve the reliability of the connection portion between the sensor coil of the torque sensor and the circuit board and to facilitate the assembly, a part of the outer peripheral surface has been developed. When a sensor coil having a connector projection for connection is integrally projected on the sensor housing and the sensor coil is assembled to the sensor housing, the connector projection projects into the board chamber for housing the circuit board. A configuration is adopted in which a circuit board is connected to the end.
[0009]
In order to enable such assembly, a connector hole for projecting a connector projection for connection into the board chamber is provided on one end surface of the sensor housing (on the side connected to the gear housing) for fitting the sensor coil. It is provided so as to be continuous with the opening, and when the sensor coil is fitted into the sensor housing, the connector protrusion is inserted through the opening of the connector hole and protrudes to a predetermined position inside the board chamber.
[0010]
However, when such an assembly structure of the torque sensor is adopted, a part of the opening of the connector hole remains in communication with the inside of the gear housing connected to the same side of the sensor housing, and the gear passes through the communication portion. As a result of the outside air entering the inside of the housing, there is a problem that the gear made of resin for the purpose of noise reduction as described above expands including the moisture of the entering outside air. Since this expansion amount greatly affects the conditions of the outside air, it is necessary to adjust the backlash amount between the gears of the gear reduction device in accordance with the conditions of the outside air at the destination of the vehicle, for example, and the assembly cost is increased. It was an increase factor.
[0011]
The present invention has been made in view of such circumstances, and it is possible to reliably prevent outside air from entering the gear housing from the opening for assembling the torque sensor with a simple configuration. An electric power steering device that makes it easy to assemble the torque sensor, reduces the influence of outside air entering the gear reduction device inside the gear housing, and prevents an increase in assembly cost by adjusting the backlash according to the outside air conditions. The purpose is to provide.
[0012]
[Means for Solving the Problems]
An electric power steering device according to a first aspect of the present invention includes a cylindrical sensor housing, a gear housing connected to one side of the sensor housing, and a column shaft supported inside the sensor housing, An electric power steering apparatus comprising an opening for assembling a torque sensor for detecting a steering torque applied to a column shaft together with a circuit board and a connector for connecting to the circuit board, on an end surface of the sensor housing connected to the gear housing. And a seal member that is interposed between the sensor housing and the gear housing and locally seals a connector hole provided in a part of the opening for allowing the connector to pass therethrough. .
[0013]
In the present invention, the seal member interposed between the sensor housing and the gear housing is connected to a part of an opening provided in the sensor housing for assembling the torque sensor, specifically, to the circuit board. A connector hole for inserting a connector for the connector is sealed by attaching a seal member to the connector hole, and outside air that enters the gear housing through the opening including the connector hole is blocked, Thus, the influence on the gear reduction device configured as described above is reduced, the effort for adjusting the backlash between the gears is reduced, and an increase in assembly cost is prevented.
[0014]
An electric power steering apparatus according to the second invention is characterized in that the seal member in the first invention is made of an elastic material.
[0015]
In the present invention, the sealing member is made of an elastic material, and is elastically contacted with the connector hole and the periphery of the opening of the connector hole to enhance the sealing effect and effectively prevent the entry of outside air.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is a longitudinal sectional view of a main part of an electric power steering apparatus according to the present invention.
[0017]
An electric power steering apparatus according to the present invention includes a cylindrical sensor housing 10, a gear housing 11 coaxially connected to one side of the sensor housing 10, and a circular tube coaxially connected to the other side. Column housing 12 and a column shaft 1 rotatably supported in these. A lower end portion (left end portion in the figure) of the column shaft 1 protruding outside the gear housing 11 is connected to a steering mechanism (not shown), and an upper end portion (right end portion in the drawing) of the column shaft 1 protruding outside the column housing 12. ), A steering wheel (not shown) is fitted and fixed, and the column shaft 1 rotates in response to a rotation operation of the steering wheel for steering, and this rotation is transmitted to the steering mechanism. Steering is performed by the operation.
[0018]
The column shaft 1 is divided into an upper shaft 14 and a lower shaft 15 that are coaxially connected via a torsion bar 13 inside the sensor housing 10. The lower shaft 15 is supported at both ends by bearings 16 and 17 that are fitted and fixed to the lower portion of the sensor housing 10 and the lower portion of the gear housing 11, respectively. Further, the upper shaft 14 is supported by a bearing 18 fitted and fixed to the upper portion of the sensor housing 10, and a lower end portion extended inside the sensor housing 10 is formed at an upper end portion of the lower shaft 15. The support holes are supported via bushes so that the rotation of both shafts 14 and 15 occurs with good concentricity.
[0019]
With the above configuration, the upper shaft 14 and the lower shaft 15 can be rotated together by the action of the steering torque applied to the column shaft 1 by the operation of the steering wheel for steering. The torsion bar 13 to be coupled is twisted by the action of the steering torque, and a relative angular displacement corresponding to the twist of the torsion bar 13 is generated between the upper shaft 14 and the lower shaft 15. Since the direction and magnitude of the relative angular displacement correspond to the direction and magnitude of the steering torque, the steering torque can be detected using the relative angular displacement of the shafts 14 and 15 as a medium.
[0020]
Cylindrical detection rings 21 and 22 are fitted and fixed in the vicinity of the connecting portion of the upper shaft 14 and the lower shaft 15, and the detection rings 21 and 22 facing each other with a substantially constant air gap therebetween are fixed. A plurality of tooth portions are arranged in parallel on the facing end surface so that the respective half portions face each other in the circumferential direction. Outside the detection rings 21 and 22, a sensor coil 20 fitted and held in the sensor housing 10 is arranged so as to surround the opposing portions of the two, and the detection rings 21 and 22 and the sensor The torque sensor 2 is constituted by the coil 20.
[0021]
As disclosed in Patent Document 1 (Japanese Patent Publication No. 7-21433) and the like, the torque sensor 2 is formed on the opposing end faces of the detection rings 21 and 22 by energization of a coil current to the sensor coil 20. A magnetic circuit that passes through the tooth portion is formed, and the relative angular displacement between the upper shaft 14 and the lower shaft 15 due to the action of the steering torque is changed according to the change in the opposing relationship between the tooth portions of the detection rings 21 and 22 that rotate integrally therewith. The detection is performed using the increase / decrease in the magnetic resistance of the magnetic circuit, and the impedance change of the sensor coil 20 is extracted as an output.
[0022]
A substrate chamber 30 is integrally formed on the outside of the sensor housing 10 so as to be aligned with the holding position of the sensor coil 20, and a circuit for supplying power to the sensor coil 20 and taking out the output is provided inside the substrate chamber 30. The substrate 3 is fixed as described later. The sensor coil 20 is provided with a connector projection 23 for connection projecting at one place in the circumferential direction. The sensor coil 20 and the circuit board 3 are connectors formed on the peripheral wall of the sensor housing 10 as described later. It is connected via the connector protrusion 23 fitted and held in the hole 31, and the feeding of the coil current to the sensor coil 20 and the extraction of the impedance of the sensor coil 20 are performed via the circuit board 3. is there.
[0023]
The detection result of the steering torque by the torque sensor 2 configured as described above is used for driving control of the steering assist motor 4 attached to the outside of the gear housing 11. The gear housing 11 is engaged with the worm wheel 50 that is fitted and fixed between the support portions of the bearings 16 and 17 in the middle of the lower shaft 15 and the teeth on the outer periphery of the worm wheel 50 from the tangential direction. The worm gear reduction device 5 is configured to include the worm 51 that performs the above operation. The steering assist motor 4 has an axis substantially perpendicular to the column shaft 1 and is attached to the outside of the gear housing 11. The output end of the motor 4 extending inside the gear housing 11 has a worm gear. Coaxially connected to the worm 51 of the reduction gear 5.
[0024]
With the above configuration, the rotation of the steering assisting motor 4 is transmitted to the column shaft 1 (output shaft 15) through deceleration by the worm gear reduction device 5 inside the gear housing 11, and the rotation of the column shaft 1 is transmitted to the steering mechanism. Then, the steering performed as described above is assisted by the operation of the steering mechanism. Here, the outer peripheral portion of the worm wheel 50 in which the teeth that mesh with the worm 51 are formed (the portion shown by hatching in FIG. 1) is made of a resin material, and meshes with the worm 51 accompanying the transmission described above. The sound is reduced.
[0025]
FIG. 2 is an external perspective view of the sensor housing 10 as viewed from the connection side with the gear housing 11. As shown in this figure, the sensor housing 10 has a cylindrical shape in which the sensor coil 20 of the torque sensor 2 can be fitted, and a rectangular chamber that can accommodate the circuit board 3 at one location on the outer periphery. A connector hole 31 penetrating the peripheral wall of the gear housing 11 is formed in the approximate center of the substrate chamber 30. The substrate chamber 30 and the connector hole 31 are extended toward the connection side with the gear housing 11 and communicated with a rectangular opening 32 formed on the end surface on the same side.
[0026]
A bearing seat 19 for internally fitting and holding a bearing 16 that supports the lower shaft 15 is formed on the end surface of the sensor housing 10 in an annular shape that is partially cut off by an opening 32 that continues to the substrate chamber 30 and the connector hole 31. There is no circumference. In FIG. 2, the sensor coil 20 fitted and held in the gear housing 11 and the bearing 16 fitted and held in the bearing seat 19 are shown together.
[0027]
FIG. 3 is an explanatory diagram of a procedure for assembling the sensor coil 20 of the torque sensor 2 to the sensor housing 10 configured as described above. In this assembly, first, the target sensor coil 20 is positioned on one side of the sensor housing 10 as indicated by a two-dot chain line in FIG. 3A, and then as indicated by an arrow in FIG. 3, and the connector protrusion 23 projecting from the outer periphery of the sensor coil 20 is fitted into the connector hole 31 through the opening 32, and as shown in FIG. The one end surface of the sensor coil 20 is brought into contact with the step portion 24 provided on the inner back side of the peripheral surface, and the tip of the connector protrusion 24 is protruded to the substantially central portion of the substrate chamber 30, and finally, the sensor coil 20 A retaining ring 25 engaged with the inner peripheral surface of the sensor housing 10 is brought into contact with the other end surface via a leaf spring 26 to restrain the sensor coil 20 from moving in the axial direction, and to the substrate chamber 30. The circuit board 3 is attached to the tip of the connector protrusion 24 protruding inward. Continue to complete the circuit board 3, and allowed fixed in position inside the substrate chamber 30 by fixing means such as screwing.
[0028]
In the electric power steering apparatus according to the present invention, as described above, one side of the sensor housing 10 in which the sensor coil 20 and the circuit board 3 are assembled is arranged on one side of the gear housing 11 in which the lower shaft 15 and the worm gear reduction device 5 are assembled. 1 and is coaxially connected by tightening connection flanges provided around both end faces, and is configured as shown in FIG. The connection as described above is performed in a state in which the bearing 16 is fitted and held in a bearing seat 19 provided around one end face of the sensor housing 10, and the lower shaft 15 protruding to the same side of the gear housing 11 by the bearing 16. Is supported.
[0029]
Here, as described above, a part of the bearing seat 19 that holds the bearing 16 is notched by the opening 32 connected to the substrate chamber 30 and the connector hole 31, and the inside of the gear housing 11 is interposed through the opening 32. The sensor housing 10 communicates with the inside. In the present invention, the seal member 6 is interposed between the sensor housing 10 and the gear housing 11 so as to locally block the communication portion by the opening 32 as described above.
[0030]
FIG. 4 is an external perspective view of the seal member 6. The appearance of the seal member 6 viewed from the opposite side is shown in FIG. 2, and the side sectional shape of the seal member 6 is shown in FIGS. 1 and 3 (b). As shown in these figures, the seal member 6 is connected to a rectangular block-shaped seal portion 60 having a width corresponding to the opening 32 connected to the substrate chamber 30 and the connector hole 31 and to one side of the seal portion 60. The holding portion 61 is preferably formed of an elastic material such as rubber. The holding part 61 has a shape in which a part of an annular ring having an outer diameter corresponding to the inner diameter of the gear housing 11 and an inner diameter corresponding to the outer diameter of the bearing 16 is cut out wider than the seal part 60. The seal portion 60 includes a stopper edge 62 that protrudes inwardly by an appropriate length from the inner diameter of the holding portion 61.
[0031]
As shown in FIGS. 2 and 3 (b), the seal member 6 configured in this way is positioned with the protruding side of the seal portion 60 facing the outside of the opening 32 provided on the end surface of the sensor housing 10. As shown by arrows in FIG. 3B, the seal portion 60 is fitted into the opening 32, and the end surface on the same side of the holding portion 61 that extends outside the seal portion 60 is brought into contact with the end surface of the sensor housing 10 for attachment. It is done.
[0032]
With this attachment, the outer surface of the seal portion 60 is brought into contact with the inner edge of the opening 32, and the inner surface of the holding portion 61 is continuous with the inner surface of the bearing seat 19 and is internally fitted and held by the bearing seat 19 as described above. The outer surface of the bearing 16 is brought into contact with the outer peripheral surface of the bearing 16, and the outer surface of the holding portion 61 is brought into contact with the inner peripheral surface of the gear housing 11 connected to the sensor housing 10 as described above. As shown in FIG. 4, the sealing member 6 is closed, and the communication portion between the sensor housing 10 and the gear housing 11 can be reliably sealed.
[0033]
Therefore, the outside air entering the inside of the gear housing 11 through the sensor housing 10 is blocked, and the possibility that the resin worm wheel 50 inside the gear housing 11 expands due to the action of moisture in the outside air is reduced. As a result, the backlash amount between the worm 51 and the worm wheel 50 can be set without considering the condition of the outside air in use, and an increase in the assembly cost of the worm gear reduction device 5 can be prevented. It becomes.
[0034]
Further, as described above, when the seal member 6 made of an elastic material such as rubber is used, the seal member 6 is elastically deformed at the contact portions with the sensor housing 10, the gear housing 11 and the bearing 16, and the seals are respectively sealed. The stopping is strengthened, and it is possible to more reliably prevent the outside air from entering the gear housing 11. The seal member 6 made of an elastic material is elastically contacted with a bearing 16 that supports the lower shaft 15, and vibrations transmitted to the lower shaft 15 through the worm wheel 50 in accordance with the deceleration transmission from the motor 4 for assisting steering. Therefore, it is possible to suppress the generation of sound due to this vibration and perform a quiet operation.
[0035]
The torque sensor 2 configured in the sensor housing 10 is not limited to the illustrated configuration disclosed in Japanese Patent Publication No. 7-21433 and the like, and various known configurations can be adopted. The gear reduction device configured inside is not limited to the worm gear reduction device 5 shown in the embodiment, and an appropriate gear reduction device using a hypoid gear, a spur gear, a bevel gear, or the like can be used.
[0036]
【The invention's effect】
As mentioned above and described in detail in the electric power steering apparatus according to the present invention, the sealing member is attached to the connector holes constituting a part of an opening provided in the sensor housing for assembly of the torque sensor, the connector by the sealing member Since the holes are locally sealed, it is possible to reliably prevent the outside air from entering the gear housing from the opening portion of the connector hole with a simple configuration, and the assembly cost can be reduced by adjusting the backlash according to the conditions of the outside air. The present invention has an excellent effect such that it is possible to prevent the increase.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a main part of an electric power steering apparatus according to the present invention.
FIG. 2 is an external perspective view of the sensor housing as viewed from the connection side with the gear housing.
FIG. 3 is an explanatory diagram of a procedure for assembling a sensor coil of a torque sensor to a sensor housing.
FIG. 4 is an external perspective view of a seal member.
[Explanation of symbols]
1 Column shaft 2 Torque sensor 6 Seal member
10 Sensor housing
11 Gear housing
23 Connector protrusion
32 openings

Claims (2)

A sensor housing forming a cylindrical, and a gear housing connected to one side of the sensor housing, and a column shaft which is supported on these internal, a torque sensor for detecting steering torque applied to the column shaft, the circuit In the electric power steering apparatus provided with an opening for assembling together with a board and a connector for connection with the circuit board on an end face on the connection side with the gear housing of the sensor housing ,
An electric power comprising: a seal member interposed between the sensor housing and the gear housing and locally sealing a connector hole provided in a part of the opening for allowing the connector to pass therethrough. Steering device. The electric power steering apparatus according to claim 1, wherein the seal member is made of an elastic material.

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