JP2010023656A - Motor unit and electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor unit capable of simply achieving the transmission of the rotation from a worm shaft to a worm wheel without occupying a large area around the worm wheel, and an electric power steering device using the same. <P>SOLUTION: A worm shaft 2 having a worm part 20 in the middle of the shaft longitudinal direction is supported by bearings 21, 22 at both ends inside a housing 10. Two motors 3a, 3b are juxtaposed inside the housing 10 so as to be parallel to the worm shaft 2. Driving gears 31, 32 at output ends of the motors 3a, 3b are engaged with a driven gear 23 fixed to the worm shaft 2 on one side of the worm part 20, and the rotation of the motors 3a, 3b is transmitted to the worm shaft 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor unit that is made compact by integrating a motor and a speed reducer, and an electric power steering apparatus using the motor unit.

  In recent years, an electric power steering apparatus equipped in many automobiles detects a steering torque applied to a steering member such as a steering wheel, obtains a target auxiliary force based on the detected steering torque, and generates the target auxiliary force. Therefore, the steering assist motor is driven and controlled, and the generated force of the motor is applied to the steering mechanism to assist the steering.

  This electric power steering apparatus changes the correspondence relationship between the steering torque and the target auxiliary force based on the detection result of the running state that affects the steering, such as the vehicle speed, the yaw rate, the steering angle, and the steering speed. While having an advantage that an assisting force characteristic suitable for the traveling state can be obtained, there is a problem that a large motor that generates an output necessary for assisting steering is required, and it is difficult to secure a space for disposing the motor.

  In particular, in a column assist type electric power steering apparatus configured to attach a motor for assisting steering in the middle of a steering column and transmit the rotational force of the motor to a steering shaft supported inside the steering column, It is important to downsize the steering assist motor that occupies the driver's foot space and is located inside the cabin, and the rotational force of the steering assist motor is decelerated (increased) by the reducer and transmitted to the steering shaft. The miniaturization of the motor is attempted. As the speed reducer, since a large reduction ratio can be obtained with a compact configuration, a worm gear speed reduction in which a worm connected to the output end of the steering assist motor is engaged with a worm wheel fixed in the middle of the steering shaft. The machine is widely used (see, for example, Patent Document 1).

Furthermore, in the electric power steering apparatus disclosed in Patent Document 1, two motors for assisting steering are provided, and each output is transmitted to both ends of a single worm, thereby reducing the size of each motor. When a large auxiliary force is required, both motors are driven to eliminate the shortage of steering auxiliary force.
JP 2007-137099 A

  As described above, in the column assist type electric power steering apparatus, the worm gear reducer is used to reduce the transmission of the rotation of the steering assist motor to the steering shaft, and the steering assist motor is connected to the steering shaft. It is connected to the end of the worm that meshes with the secured worm wheel.

  Here, the worm and the worm wheel of the worm gear reducer are supported by having axes that are orthogonal to each other, and are configured by meshing the worm with the worm teeth on the outer periphery of the worm wheel. Therefore, the steering assist motor connected to one end of the worm must be mounted on the outside of the steering column that supports the worm wheel so that it protrudes in the tangential direction of the worm wheel. However, the effect of reducing the occupied area in the axial section of the steering column is small, and there is a problem that the original purpose of securing the driver's foot space cannot be achieved.

  As in the above electric power steering device, transmission devices configured to take out the rotation of the motor through the worm and the worm wheel are widely adopted in various industrial fields, and in these transmission devices, There is an urgent need to reduce the length of the motor protruding to the outside of the housing that houses the output shaft and worm wheel, thereby reducing the size of the transmission.

  The present invention has been made in view of such circumstances. The worm shaft and the motor are compactly arranged in a common housing to form a unit, and the worm shaft is attached to the housing that supports the worm wheel. It is an object of the present invention to provide a motor unit that can be simply realized without occupying a large area around the worm wheel, and to provide an electric power steering device using the motor unit.

  A motor unit according to a first aspect of the present invention includes a worm shaft having a worm portion in the middle of the axial length direction, a housing that supports the worm shaft on both sides of the worm portion, and the worm shaft inside the housing. A plurality of motors are provided in parallel with the shaft and each output end is interlocked and connected to the worm shaft.

  A motor unit according to a second invention of the present invention is such that the plurality of motors in the first invention have output ends extending in the same direction, and drive gears of the respective output ends are arranged on one side of the worm portion. It is engaged with the worm shaft by meshing with a driven gear fixed to the worm shaft.

  According to a third aspect of the present invention, there is provided a motor unit, wherein the plurality of motors according to the first aspect have output ends extending in opposite directions, and drive gears at the respective output ends are arranged on both sides of the worm portion. The driven gear is individually meshed with the worm shaft and interlocked with the worm shaft.

  According to a fourth aspect of the present invention, there is provided a motor unit in which the plurality of motors according to the first aspect have two output ends respectively extending on both sides in the axial length direction, and the drive gears at the respective output ends. Is engaged with the driven gears on both sides of the worm portion and interlocked with the worm shaft.

  In the motor unit according to the fifth aspect of the present invention, the drive gears at the output ends on both sides of the motor according to the fourth aspect are attached to the respective output ends via the clutch means, and the drive gear on one side is the same side The driven gear is meshed with an intermediate gear through an intermediate gear.

  According to a sixth aspect of the present invention, there is provided an electric power steering apparatus that transmits a rotational force of a steering assist motor driven in accordance with an operation of a steering member to a steering shaft that communicates the steering member and a steering mechanism. In the electric power steering apparatus for assisting steering executed by the operation of the take-off mechanism, the motor unit of any one of the first to fifth inventions is provided as the steering auxiliary motor, and the worm is fixed to the worm wheel fixed to the steering shaft. The worm portion of the shaft is meshed.

  In the motor unit according to the first invention, the worm shaft and the plurality of motors are arranged side by side in a common housing, and the output end of each motor is linked to the worm shaft to rotationally drive the worm shaft. The motor does not protrude in the axial direction of the shaft, and the use of multiple motors reduces the size of each motor and reduces the radial dimension of the worm shaft. Transmission from the worm shaft to the worm wheel Can be realized simply by suppressing the area occupied around the worm wheel.

  In the motor unit according to the second aspect of the invention, the drive gears at the output ends of the plurality of motors are engaged with the driven gear fixed to the worm shaft, and the motor and the worm shaft are interlockedly connected. Therefore, the motor can be reliably decelerated and the motor can be reduced in size.

  In the motor unit according to the third aspect of the invention, the output ends of the plurality of motors extend in the reverse direction, and the drive gears of the respective output ends are meshed with the respective driven gears fixed to the worm shaft. The meshing reaction forces applied to the meshing portions of the drive gear and the driven gear of the motor are canceled out, and stable transmission can be realized.

  In the motor unit according to the fourth aspect of the present invention, a motor having output ends on both sides in the axial direction is used, and the drive gears at the respective output ends are engaged with the respective driven gears fixed to the worm shaft. And the meshing reaction force applied to the meshing portion of the driven gear are canceled by each of the plurality of motors, and stable transmission can be realized.

  In the motor unit according to the fifth aspect of the invention, since the clutch means interposed between the output ends of the plurality of motors and the drive gear blocks the reverse input from the driven gear, the inertia of the motor in the non-rotating state is warm. Without being added to the shaft and the worm wheel, the worm wheel and the worm shaft can be idled without being affected by the inertia of the motor. In addition, since the drive gear on one side is engaged with the driven gear via the intermediate gear, the output rotations of a plurality of motors are collectively transmitted to the driven gears, and the worm shafts are moved forward and backward without changing the rotation direction of each motor. It can be rotationally driven in both directions.

  In the electric power steering device according to the sixth aspect of the present invention, the motor for assisting the steering can be provided while suppressing the occupied area around the steering shaft to be transmitted, and the driver's foot space is sufficiently secured. In addition, it is possible to reduce the possibility that the driving operation by the foot such as the accelerator operation and the brake operation is hindered.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is a longitudinal sectional view showing a first embodiment of a motor unit according to the present invention, and FIG. 2 is a transverse sectional view taken along line II-II in FIG.

  The motor unit 1 according to the present invention includes a worm shaft 2 housed in a common housing 10 and two motors 3a and 3b. The worm shaft 2 includes a worm portion 20 that is integrally formed with a central portion in the axial length direction having a large diameter over an appropriate length. Bearings 21 and 22 on both sides of the worm portion 20 are provided inside the housing 10. Both ends are supported.

  Furthermore, the worm shaft 2 includes a driven gear 23 that is coaxially fitted and fixed between one side of the worm portion 20 and a bearing 21 that supports the worm portion 20. The driven gear 23 shown as a disk in FIG. 1 is a large-diameter spur gear with teeth (straight teeth or inclined teeth) provided on the entire outer surface as shown in FIG. Drive gears 31 and 32 fixed to the output ends of the two motors 3a and 3b are meshed at different positions in the circumferential direction.

  As shown in FIG. 1, the motor 3a is mounted in parallel with the worm shaft 2 at a position overlapping the worm portion 20 at the center of the worm shaft 2 in the axial direction. A motor 3b not shown in FIG. 1 is attached in parallel to the worm shaft 2 at a position overlapping the motor 3a in a direction perpendicular to the paper surface. The output end of the motor 3a (and the motor 3b) extends toward the driven gear 23, and the drive gear 31 (and the drive gear 32) are fixed to each output end.

  As described above, the housing 10 that supports the worm shaft 2 and the motors 3a and 3b includes the opening 11 that is opened over the entire length of the worm portion 20 on the side away from the support position of the motors 3a and 3b. On the outside of the opening 11, a fixed seat 12 flattened over an appropriate width is provided over the entire circumference.

  The motor unit 1 configured as described above is fixed by tightening a fixing bolt (not shown) by aligning the fixed seat 12 of the housing 10 with the corresponding seat 41 of the worm housing 40 indicated by a two-dot chain line in FIG. The worm portion 20 exposed from the opening 11 is used by being engaged with the worm wheel 4 supported in the worm housing 40.

  As shown in FIGS. 1 and 2, an elastic sheet 13 made of an elastic material such as rubber is interposed between the fixed seat 12 and the seat portion 41. The elastic sheet 13 functions as a sealing material that hermetically seals between the fixed seat 12 and the seat portion 41. The elastic sheet 13 is deformed according to the tightening degree of the fixing bolt, and is used as a means for adjusting the backlash at the meshing portion between the worm portion 20 and the worm wheel 4.

  When one or both of the motors 3a and 3b are driven under the above use conditions, the respective rotational outputs are transmitted to the driven gear 23 via the drive gears 31 and 32 at the output end, and the driven gear 23 is fixedly installed. The worm shaft 2 thus rotated rotates. The rotation of the worm shaft 2 is transmitted to the worm wheel 4 meshing with the worm portion 20, and an output shaft (not shown) to which the worm wheel 4 is attached is rotationally driven.

  The motor unit 1 is parallel to the worm shaft 2 and has motors 3a and 3b arranged on the worm portion 20 side, and the worm shaft 2 is driven to rotate by the rotation of these motors 3a and 3b. As shown in FIG. 1, there is no protrusion on one side or both sides of the worm shaft 2 in the axial direction.

  The motor unit 1 also includes two motors 3a and 3b. The resultant force of the rotational outputs of the motors 3a and 3b is wormed via a driven gear 23 that meshes with the drive gears 31 and 32 at their output ends. It is configured to be transmitted to the shaft 2. Furthermore, the driven gear 23 has a larger diameter than the drive gears 31 and 32, and the rotation of the motors 3a and 3b is reduced and transmitted to the driven gear 23. Therefore, compared with a motor widely used in an electric power steering apparatus to be described later, small motors 3a and 3b with a small output can be used, and a height dimension H (see FIG. 1) from the fixed seat 12 is also small. Can be suppressed.

  As described above, the motor unit 1 according to the present invention has the worm housing 40 around the worm housing 40 that accommodates the worm wheel 4 in the use state shown in FIGS. Therefore, a transmission device that takes out the rotation of the worm wheel 4 as an output by using the motor unit 1 as a drive source can be configured in a compact manner.

  The two motors 3a, 3b of the motor unit 1 are selectively driven according to the magnitude of the output to be transmitted to the worm wheel 4. For example, when high output is required, both motors 3a and 3b are driven, and when high output is not required, only one motor 3a (or 3b) is driven. Output control can be performed.

  In the above use state, the reaction force in various directions is applied to the worm shaft 2 of the motor unit 1 from the worm wheel 4 meshing with the worm portion 20, but the housing 10 and the worm wheel 4 of the motor unit 1 are supported. The elastic sheet 13 is interposed between the worm housing 40 and the worm housing 40, and the elastic sheet 13 exists on the entire circumference of the opening 11 provided to expose the worm part 20. Therefore, the worm shaft 2 can be displaced in an appropriate direction in the plane of the opening 11 with the deformation of the elastic sheet 13, and the worm shaft 2 and the worm wheel 4 are always kept in an appropriate meshing state, and are quiet. Transmission can be realized.

  FIG. 3 is a schematic diagram of an electric power steering apparatus according to the present invention. This electric power steering apparatus includes a steering mechanism 5 for turning steering wheels 50, 50 disposed on the left and right sides of a vehicle body, and a steering wheel (steering member) 6 that is rotated for steering. The motor unit 1 according to the present invention is provided as a steering assist motor that applies a steering assist force according to the operation of the steering wheel 6 to the steering mechanism 5.

  The steering mechanism 5 includes a rack shaft 52 supported so as to be movable in the axial length direction inside a cylindrical rack housing 51 extending in the left-right direction, and a pinion housing 53 that crosses the rack housing 51 in the middle. This is a known rack and pinion type steering mechanism including a pinion shaft 54 rotatably supported therein.

  Both ends of the rack shaft 52 projecting outward from both sides of the rack housing 51 are connected to left and right steering wheels 50, 50 via separate tie rods 55, 55. Further, an end portion of the pinion shaft 54 that protrudes to the outside of the pinion housing 53 is connected to the steering shaft 60 via an intermediate shaft 56. A pinion (not shown) is provided on a half of the pinion shaft 54 extending inside the pinion housing 53, and the pinion is formed on the outer surface of the rack shaft 52 at an appropriate length at the intersection with the rack housing 51. Meshed with the rack.

  The steering shaft 60 is rotatably supported inside a cylindrical column housing 61, and is attached to the interior of a vehicle compartment (not shown) while maintaining an inclined posture with the front facing down. The upper and lower ends of the steering shaft 60 protrude outside the column housing 61. A steering wheel 6 is attached to the protruding end of the steering shaft 60 in the rear upper direction of the column housing 61. Similarly, the protruding end of the steering shaft 60 in the front lower direction is connected to the pinion shaft 54 via the intermediate shaft 56 described above. It is connected.

  With the above configuration, when the steering wheel 6 is rotated for steering, this rotation operation is transmitted to the pinion shaft 54 via the steering shaft 60 and the intermediate shaft 56, and the pinion shaft 54 rotates. The rotation of the pinion shaft 54 is converted in motion at the meshing portion of the pinion and the rack and transmitted to the rack shaft 52. The rack shaft 52 is moved in the axial length direction, and this movement is performed by the wheels by the respective tie rods 55 and 55. 50, 50, and these wheels 50, 50 are steered.

  The lower part of the column housing 61 that rotatably supports the steering shaft 60 has a large diameter, and the sensor housing 62 and the worm housing 40 are arranged side by side in the vertical direction. Inside the sensor housing 62, a torque sensor 63 for detecting a steering torque applied to the steering shaft 60 by the operation of the steering wheel 6 is provided. The torque sensor 63 divides the steering shaft 60 to be detected into two upper and lower axes that are coaxially connected by a torsion bar having a known torsion characteristic, and the relative generated by the torsion bar being twisted between these two axes. It has a known configuration for detecting angular displacement.

  A worm wheel 4 fitted to the steering shaft 60 is disposed inside the worm housing 40. The motor unit 1 according to the present invention having the above-described configuration is attached to the outside of the worm housing 40 as shown in FIGS. The output rotation of 3b is transmitted to the worm wheel 4 via the worm shaft 2 and applied to the steering shaft 60, and the steering performed as described above according to the rotation of the steering shaft 60 is assisted by the output of the motor unit 1. It has a transmission configuration.

  The motor unit 1 is driven in accordance with a control command given from the assist control unit 7. The assist control unit 7 is provided with the detected value of the steering torque from the torque sensor 63 described above, and is also provided with the detected value of the running speed of the vehicle from the vehicle speed sensor 64 disposed in an appropriate part of the vehicle. .

  The assist control unit 7 includes a CPU, a ROM, and a RAM. By the operation of the CPU according to a control program stored in the ROM, the motor unit 1 according to the present invention, more specifically, two motors 3a built in the motor unit 1 are provided. , 3b is executed as an object to be controlled. In the assist control operation, the detected value of the steering torque given from the torque sensor 63 is applied to a preset control map to determine a target auxiliary force as a control amount, and the motor unit 1 is driven to generate this target auxiliary force. This is a known operation to control.

  A plurality of control maps used for determining the target assist force are prepared according to the vehicle speed, and are selected and used according to the detected value of the vehicle speed by the vehicle speed sensor 64. As a result, the assist force characteristics are made different according to the level of the vehicle speed. For example, when the road surface reaction force applied to the steering wheels 50 and 50 is small, the steering assist force generated by the motor unit 1 is reduced to reduce the steering force. The wheel 6 can be given a sense of rigidity, and stable running without wobbling can be realized. Conversely, when the road surface reaction force is large and the vehicle is stopped at low speeds, the steering assist force is increased so that the steering wheel 6 can be operated. It is possible to perform it lightly and reduce the labor burden on the driver required for steering.

  As described above, the motor unit 1 used for assisting steering has the two motors 3a and 3b. The output rotation of these motors 3a and 3b is caused by the drive gears 31 and 32, the driven gear 23, and the like. Is transmitted to the worm shaft 2, and further decelerated by the worm shaft 2 and the worm wheel 4 and transmitted to the steering shaft 60. Therefore, a sufficient steering assist force can be generated by the small and small output motors 3a and 3b.

  Further, as described above, the motor unit 1 does not occupy a large area around the worm housing 40, that is, around the column housing 61, and ensures a sufficient space around the foot of the driver who operates the steering wheel 6. Therefore, there is no possibility of hindering the driving operation by the foot such as the accelerator operation and the brake operation.

  The assist control unit 7 selectively drives the two motors 3a and 3b of the motor unit 1 according to the magnitude of the output to be transmitted to the worm wheel 4, and when the target assist force is large as described above. Both motors 3a and 3b are driven together, and only one motor 3a (or 3b) is driven when the target auxiliary force is small. As a result, the assist control operation can be performed with high accuracy over a wide range.

  When brushless motors are employed as the motors 3a and 3b, it is necessary to detect their respective rotational positions in order to drive them. Here, as described above, the two motors 3a and 3b have the drive gears 31 and 32 at their output ends meshed with the common driven gear 23, and rotate in synchronization with each other. Therefore, a rotational position detector can be attached to only one of the two motors 3a and 3b, and both motors 3a and 3b can be driven based on the detection result of the rotational position detector. With this configuration, the number of rotational position detectors can be reduced.

  FIG. 4 is a longitudinal sectional view showing a second embodiment of the motor unit according to the present invention, and FIG. 5 is a view taken along the line VV in FIG. The motor unit 1 shown in the figure includes a worm shaft 2 and two motors 3a and 3b housed in a common housing 10 as in the motor unit 1 shown in the first embodiment.

  In this second embodiment, the worm shaft 2 includes a driven gear 23 on one side of the central worm portion 20 and a driven gear 24 on the other side of the worm portion 20. The two motors 3a and 3b arranged in parallel with the worm part 20 have output ends extending in opposite directions, and a drive gear 31 fixed to the output end of the motor 3a is engaged with the driven gear 23. A driving gear 32 fixed to the output end of the motor 3b is engaged with the driven gear 24. Other configurations are the same as those of the embodiment shown in FIGS. 1 and 2 including the usage pattern, and the corresponding components are denoted by the same reference numerals as those in FIGS.

  In this embodiment, the directions of the reaction forces applied from the driven gears 23 and 24 meshed with the drive gears 31 and 32 at the output ends of the two motors 3a and 3b are reversed and cancel each other. , 3b is not subjected to rotational force in the plane shown in FIG. 5, that is, in the mounting surface to the worm housing 40, and stable transmission is possible.

  FIG. 6 is a longitudinal sectional view showing a third embodiment of the motor unit according to the present invention, and FIG. 7 is a view taken along the line VII-VII in FIG. The motor unit 1 shown in this figure is also provided with a worm shaft 2 and two motors 3a and 3b housed in a common housing 10 in the same manner as the motor unit 1 shown in the first and second embodiments. Yes.

  In this third embodiment, the worm shaft 2 includes driven gears 23 and 24 fixed to both sides of the central worm portion 20 as in FIGS. On the other hand, the two motors 3a and 3b arranged in parallel with the worm portion 20 have output ends extending on both sides in the axial length direction, and are fixed to the output ends on one side of the motors 3a and 3b, respectively. The driven gears 31a and 31b are meshed with the driven gear 23, and the driven gears 32a and 32b fixed to the other output ends of the motors 3a and 3b are meshed with the driven gear 24, respectively. The other configuration is the same as that of the embodiment shown in FIGS. 1 and 2 including the usage pattern, and the corresponding components are denoted by the same reference numerals as those in FIGS. 1 and 2 and the description thereof is omitted.

  In this embodiment, the directions of the reaction forces applied from the driven gears 23 and 24 that mesh with the drive gears 31a and 32a at the two output ends of the motor 3a are opposite in plan view shown in FIG. Offset. Such cancellation of reaction force also occurs in the other motor 3b. Accordingly, stable transmission is possible not only when both the motors 3a and 3b are driven, but also when only one of the two motors 3a and 3b is driven.

  FIG. 8 is a longitudinal sectional view showing a fourth embodiment of the motor unit according to the present invention, and FIG. 9 is a view taken along the line IX-IX in FIG. Similarly to the motor unit 1 shown in the first to third embodiments, the motor unit 1 shown in the figure also includes a worm shaft 2 and two motors 3a and 3b housed in a common housing 10. Yes.

  In this embodiment, the worm shaft 2 includes driven gears 23 and 24 fixed to both sides of the central worm portion 20 as in the second and third embodiments. On the other hand, one motor 3a arranged in parallel with the worm portion 20 has output ends extending on both sides in the axial direction via separate electromagnetic clutches 34a and 35a. The drive gear 31a fixed to the worm portion 20 on one side of the driven gear 23 and the drive gear 32a fixed to the other output end of the worm portion 20 on the other side of the driven gear 24 are as shown below. Meshed.

  Similarly, the other motor 3b arranged in parallel with the worm portion 20 has output ends extending on both sides in the axial direction via the respective electromagnetic clutches 34b and 35b, and one output end The drive gear 31b fixed to the worm portion 20 on one side of the driven gear 23 and the drive gear 32b fixed to the other output end of the worm portion 20 on the other side of the driven gear 24 are as shown below. Meshed.

  FIG. 10 is an explanatory view showing the meshed state of the drive gear and the driven gear on both sides of the motor. FIG. 10 (a) shows the meshed state of the drive gears 31a, 31b and the driven gear 23 in FIG. b) shows the meshing state of the drive gears 32a, 32b and the driven gear 24, respectively. As shown in the figure, the drive gears 31a and 31b on one side of the motors 3a and 3b are directly meshed with different positions on the circumference of the driven gear 23, whereas the drive gears 32a and 32b on the other side are driven. The gears 24 are engaged at different positions on the circumference of the gear 24 via different intermediate gears (counter gears) 33a and 33b. In these figures, the illustration of teeth provided on the circumference of each gear is omitted.

  The electromagnetic clutches 34a, 35a, 34b, 35b are well-known clutch means that perform an engaging operation in response to the supply of excitation current, and the drive gears 31a, 32a, 31b, 32b at the output ends of the motors 3a, 3b When the electromagnetic clutches 34a, 35a, 34b, 35b are in a non-engagement state while being driven to rotate by engagement of another electromagnetic clutch 34a, 35a, 34b, 35b, the drive gears 31a, 32a, 31b, 32b respectively And the motors 3a and 3b are cut off.

  In this embodiment, the motors 3a and 3b are rotationally driven in opposite directions, and the electromagnetic clutches 34a and 35b located diagonally in FIG. 9 are engaged and the electromagnetic clutches 35a and 34b are disengaged. (Or the electromagnetic clutches 35a and 34b are engaged and the electromagnetic clutches 34a and 35b are disengaged). When the electromagnetic clutches 34a and 35b are engaged, the rotation of the motor 3a is transmitted to the driven gear 23 via the drive gear 31a, and the rotation of the motor 3b is transmitted to the driven gear 24 via the drive gear 32b and the intermediate gear 33b. The worm shaft 2 is rotationally driven in one direction by the resultant force of the two motors 3a and 3b.

  On the other hand, when the electromagnetic clutches 35a and 34b are engaged, the rotation of the motor 3a is transmitted to the driven gear 24 via the drive gear 32a and the intermediate gear 33a, and the rotation of the motor 3b is transmitted to the driven gear 23 via the drive gear 31b. The worm shaft 2 is rotationally driven in the direction opposite to that when the electromagnetic clutches 34a and 35b are engaged by the resultant force of the driving forces of the two motors 3a and 3b.

  In this way, the two motors 3a and 3b are driven in their respective directions, and the electromagnetic clutches 34a, 35a, 34b and 35b provided at the respective output ends are selectively engaged to rotate the motors 3a and 3b. The worm shaft 2 can be driven to rotate in both directions without switching the directions (the rotation directions of the motors 3a and 3b are one each). The electromagnetic clutches 34a, 35a, 34b, and 35b are kept in the disengaged state while the respective motors 3a and 3b are in the non-driven state. When the worm shaft 2 is rotated by reverse input from the worm wheel 4 in this state, this rotation is transmitted to the drive gears 31a and 31b at the output end on one side of the motors 3a and 3b via the driven gear 23 and is also driven. It is transmitted to the drive gears 32a and 32b on the other output side of the motors 3a and 3b via the gears 24 and the intermediate gears 33a and 33b, but is cut off by the electromagnetic clutches 34a, 35a, 34b and 35b to the motors 3a and 3b Is not transmitted. Therefore, the worm wheel 4 meshing with the worm shaft 2 and the worm portion 20 can freely rotate without adding the inertia of the motors 3a and 3b.

  This is important in application to the electric power steering apparatus shown in FIG. That is, when the driver releases his hand from the steering wheel 6 and returns to the straight traveling state, a reverse input accompanying the returning operation of the steering mechanism 5 is applied to the motor unit 1 via the worm wheel 4. Since the electromagnetic clutches 34a, 35a, 34b, and 35b are disconnected, the motors 3a and 3b that are not driven do not rotate. Therefore, the inertia of both motors 3a and 3b does not affect the return operation of the steering mechanism 1, and a good steering feeling can be realized.

  Also in this embodiment, as in the third embodiment, the reaction forces applied to the output ends of the two motors 3a and 3b cancel each other. As a result, the housing 10 that supports the motors 3a and 3b has a structure shown in FIG. In this plane, that is, the rotational force in the mounting surface to the worm housing 40 is not applied, and stable transmission is possible.

  In the above embodiment, the case where the motor unit 1 includes the two motors 3a and 3b has been described. However, the number of motors arranged in parallel is as long as transmission to the driven gear 23 or the driven gears 23 and 24 is possible. Three or more may be sufficient.

It is a longitudinal section showing a 1st embodiment of a motor unit concerning the present invention. It is a cross-sectional view by the II-II line of FIG. 1 is a schematic diagram of an electric power steering apparatus according to the present invention. It is a longitudinal section showing a 2nd embodiment of a motor unit concerning the present invention. It is an arrow view by the VV line of FIG. It is a longitudinal cross-sectional view which shows 3rd Embodiment of the motor unit based on this invention. It is an arrow view by the VII-VII line of FIG. It is a longitudinal section showing a 4th embodiment of a motor unit concerning the present invention. It is an arrow view by the IX-IX line of FIG. It is explanatory drawing which shows the meshing state of the drive gear and driven gear in the both sides of a motor.

Explanation of symbols

1 Motor unit, 2 worm shaft, 3a, 3b motor, 4 worm wheel,
5 Steering mechanism, 6 Steering wheel (steering member), 10 Housing, 20 Worm, 23, 24 Drive gear, 31, 32, 31a, 32a, 31b, 32b Drive gear, 34a, 35a, 34b, 35b Electromagnetic clutch ( Clutch means), 60 steering shaft

Claims (6)

A worm shaft having a worm portion in the middle of the axial direction;
A housing that supports the worm shaft on both sides of the worm portion;
A motor unit comprising: a plurality of motors arranged in parallel with the worm shaft inside the housing, each output end being interlocked with the worm shaft.   The plurality of motors have output ends extending in the same direction, and the drive gears of the respective output ends are meshed with driven gears fixed to one side of the worm portion, and interlocked with the worm shaft. The motor unit according to claim 1, which is connected.   The plurality of motors have output ends that extend in opposite directions, and the drive gears of the respective output ends are individually engaged with the driven gears on both sides of the worm portion to be interlocked with the worm shaft. The motor unit according to claim 1.   The plurality of motors have two output ends respectively extending on both sides in the axial direction, and the drive gears on the respective output ends are meshed with the driven gears on both sides of the worm portion, so that the worm The motor unit according to claim 1, wherein the motor unit is interlocked with the shaft.   The drive gears at the output ends on both sides of the motor are attached to the respective output ends via clutch means, and the drive gear on one side is engaged with the driven gear on the same side via an intermediate gear. 4. The motor unit according to 4. Electric power that assists the steering executed by the operation of the steering mechanism by transmitting the rotational force of the steering assist motor driven in accordance with the operation of the steering member to the steering shaft that connects the steering member and the steering mechanism. In the steering device,
A motor unit according to any one of claims 1 to 5 is provided as the steering assist motor, and a worm wheel fixed to the steering shaft is engaged with a worm portion of the worm shaft. Electric power steering device.

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