Steering device

Abstract

To provide a steering device that can increase strength against a load acting in a longitudinal direction of a rack housing.SOLUTION: A steering device includes: a plurality of mounting parts 20 provided in a rack housing 10; a plurality of mounting holes 30 disposed in the respective mounting parts 20, through which fastening members extend to couple the rack housing 10 to a vehicle frame. Each of the mounting holes 30 has a motor side mounting hole 32 and a steering side mounting hole 31. The motor side mounting hole 32 includes: a reference hole 35 that restricts the position of the rack housing 10; and an elongated hole 36 that is placed at a position different from the reference hole 35 in a direction orthogonal to a longitudinal direction of the rack housing 10 and extends in a direction intersecting the longitudinal direction of the rack housing 10. The elongated hole 36 has a width that is equal to or larger than a diameter of the reference hole 35 and is smaller than the size of the steering-side mounting hole 31 in the longitudinal direction of the rack housing 10.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a steering device.

Background Art

[0002] The steering device is attached to the vehicle body by a plurality of mount portions provided in a steering gear housing. In a conventional steering device, among the mount holes of the plurality of mount portions for positioning the steering gear housing with respect to the vehicle body, some of the mount holes are used as positioning mount holes, and the mount holes other than the positioning mount holes have a larger hole size than the positioning mount holes in order to improve the assemblability to the vehicle body.

[0003] For example, in the power steering device described in Patent Document 1, one mount hole on one side and one mount hole on the other side in the longitudinal direction of the steering gear housing are used as positioning mount holes. Further, in Patent Document 1, among these two positioning mount holes, one positioning mount hole is a reference hole that regulates the position in all directions, and the other positioning mount hole is an elongated hole extending in the longitudinal direction of the steering gear housing, and the steering gear housing is regulated in position on an arc centered on the reference hole with respect to the vehicle body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, when the vehicle is running, for example, when a wheel collides with a curb, a large load may act on the wheel. The large load acting on the wheel acts on the steering device as a load in the vehicle width direction via the tie rod. When a large load in the vehicle width direction acts on the steering device, among the plurality of mounting holes for attaching the housing to the vehicle body, the mounting hole for positioning in the vehicle width direction and the bolt for attaching the housing to the vehicle body will receive the large load.

[0006] That is, among the plurality of mounting holes for attaching the housing to the vehicle body, the mounting holes other than the mounting hole for positioning in the vehicle width direction have a gap in the direction in which the load acts between the bolts for attaching the housing to the vehicle body, making it difficult to transmit the load to the bolts. For this reason, when a large load in the vehicle width direction, that is, in the longitudinal direction of the housing that houses the rack shaft, acts on the steering device, the load is transmitted from the mounting hole for positioning in the longitudinal direction of the housing to the bolt and is received by the bolt.

[0007] Here, among the plurality of mounting holes of the housing, the mounting holes for positioning are only some of the mounting holes in consideration of the assemblability when attaching the housing to the vehicle body. Also in Patent Document 1, the mounting holes for positioning in the longitudinal direction of the housing are only the reference holes that regulate the position in all directions. However, when there is one mounting hole for positioning in the longitudinal direction of the housing, when a large load in the longitudinal direction of the housing acts on the steering device, this load will be mainly received by one bolt passed through the mounting hole for positioning in the longitudinal direction of the housing. For this reason, there is a possibility that the strength of the bolt against the load is insufficient, and there was room for improvement in the conventional steering device from the viewpoint of the strength against the load acting in the longitudinal direction of the housing.

[0008] The present disclosure has been made in view of the above, and an object thereof is to provide a steering device capable of improving the strength against a load acting in the longitudinal direction of a rack housing.

Means for Solving the Problems

[0009] The steering device of the present disclosure includes a rack bar extending linearly, a rack housing that houses the rack bar, a plurality of mount portions disposed in the rack housing, and a plurality of mount holes through which fastening members for coupling the rack housing to a vehicle body frame are passed, respectively, for each of the plurality of mount portions. The plurality of mount holes include a mount hole disposed closer to one end in the longitudinal direction of the rack housing and a mount hole disposed closer to the other end in the longitudinal direction of the rack housing. The mount hole disposed closer to the one end has a reference hole that is a round hole for restricting the position of the rack housing, and a long hole disposed at a position different from that of the reference hole in a direction orthogonal to the longitudinal direction of the rack housing and extending in a direction intersecting the longitudinal direction of the rack housing. The width of the long hole in a direction orthogonal to the extending direction of the long hole is equal to or larger than the diameter of the reference hole and smaller than the size of the rack housing in the longitudinal direction in the mount hole disposed closer to the other end.

[0010] According to this configuration, among the plurality of mounting holes of the plurality of mounting portions arranged in the rack housing, the mounting holes arranged closer to one end in the longitudinal direction of the rack housing have a reference hole for regulating the position of the rack housing and a long hole extending in a direction intersecting the longitudinal direction of the rack housing. Among these, the long hole has a width in a direction orthogonal to the extending direction of the long hole that is equal to or greater than the diameter of the reference hole and is smaller than the size in the longitudinal direction of the rack housing in the mounting hole arranged closer to the other end in the longitudinal direction of the rack housing. Therefore, when the rack housing receives a large load acting in the longitudinal direction of the rack housing and the contact surface between the mounting portion and the vehicle body frame is displaced in the longitudinal direction of the rack housing, the two mounting holes, namely the reference hole and the long hole, can be brought into contact with the fastening member. As a result, when the rack housing receives a large load in the longitudinal direction, the load can be received by the two fastening members passed through the reference hole and the long hole, and the strength against the large load acting in the longitudinal direction of the rack housing can be ensured. Consequently, the strength against the load acting in the longitudinal direction of the rack housing can be improved.

[0011] As a desirable form, the long hole extends in a direction orthogonal to the longitudinal direction of the rack housing.

[0012] According to this configuration, since the long hole extends in a direction orthogonal to the longitudinal direction of the rack housing, when a large load acting in the longitudinal direction of the rack housing acts on the rack housing, it is possible to easily bring the long hole into contact with the fastening member. As a result, when the rack housing receives a large load acting in the longitudinal direction, in addition to the fastening member passed through the reference hole, the fastening member passed through the long hole can also easily receive a large load, and the strength against the large load acting in the longitudinal direction of the rack housing can be ensured. Consequently, the strength against the load acting in the longitudinal direction of the rack housing can be improved.

[0013] Desirably, the elongated hole is disposed at the same position as the reference hole in the longitudinal direction of the rack housing.

[0014] According to this configuration, since the elongated hole is disposed at the same position as the reference hole in the longitudinal direction of the rack housing, the distance between the elongated hole and the reference hole can be minimized as much as possible. As a result, the relative dimensional error of the elongated hole with respect to the reference hole can be minimized, and thus the width in the direction orthogonal to the extending direction of the elongated hole, that is, the width of the elongated hole in the longitudinal direction of the rack housing, can be minimized as much as possible. Therefore, when a large load acting in the longitudinal direction of the rack housing acts on the rack housing, the elongated hole can be easily brought into contact with the fastening member, and in addition to the fastening member passed through the reference hole, the fastening member passed through the elongated hole can also be easily subjected to a large load. Thereby, when a large load acts on the rack housing, the two fastening members passed through the reference hole and the elongated hole can receive a large load, and the strength against the large load acting in the longitudinal direction of the rack housing can be ensured. As a result, the strength against the load acting in the longitudinal direction of the rack housing can be improved.

[0015] Desirably, on the rack bar, a first pinion gear that rotates by torque input from the steering side and a second pinion gear that rotates by the driving force generated by the electric motor mesh with each other at different positions in the longitudinal direction of the rack bar, and the electric motor is disposed at the position closest to the reference hole among the plurality of mount holes.

[0016] According to this configuration, since the electric motor is arranged at the position closest to the reference hole among the plurality of mounting holes, when attaching the rack housing to the vehicle body frame while positioning it with the fastening member through the reference hole, the force required to rotate the rack housing around the reference hole can be reduced. That is, by arranging the heavy electric motor at a position close to the reference hole, the rack housing can be rotated with a relatively small force when rotating it around the reference hole. As a result, the labor required for attaching the rack housing to the vehicle body frame can be reduced, and the rack housing can be easily attached to the vehicle body frame. As a result, the assemblability of the rack housing can be improved.

[0017] As a desirable form, the mounting hole arranged closer to the other end has a large-diameter hole which is a round hole with a diameter larger than that of the reference hole.

[0018] According to this configuration, since the mounting hole arranged closer to the other end in the longitudinal direction of the rack housing has a large-diameter hole which is a round hole with a diameter larger than that of the reference hole, the assemblability when attaching the rack housing to the vehicle body frame can be ensured. That is, since the mounting hole arranged closer to the other end in the longitudinal direction of the rack housing is at a distance from the reference hole, the relative dimensional error of the mounting hole with respect to the reference hole is likely to increase. Therefore, by having the mounting hole arranged closer to the other end in the longitudinal direction of the rack housing have a large-diameter hole with a diameter larger than that of the reference hole, even when the relative dimensional error of the large-diameter hole with respect to the reference hole is large when attaching the rack housing to the vehicle body frame, the fastening member can be passed through the large-diameter hole and through the fastening hole formed in the vehicle body frame. As a result, when attaching the rack housing to the vehicle body frame, the fastening member can be easily passed through the mounting hole at a distance from the reference hole, and the rack housing can be easily attached to the vehicle body frame. As a result, the assemblability of the rack housing can be improved.

[0019] Desirably, the mounting hole disposed closer to the other end has a long hole-shaped second long hole extending in a direction along the longitudinal direction of the rack housing.

[0020] According to this configuration, the mounting hole disposed closer to the other end in the longitudinal direction of the rack housing has a second long hole extending in a direction along the longitudinal direction of the rack housing. Therefore, when the rack housing receives a large load in a direction orthogonal to the longitudinal direction thereof, and the contact surface between the mounting portion and the vehicle body frame is displaced in a direction orthogonal to the longitudinal direction of the rack housing, the two mounting holes, i.e., the reference hole and the second long hole, can be brought into contact with the fastening member. As a result, when the rack housing receives a large load in a direction orthogonal to the longitudinal direction thereof, the two fastening members passed through the reference hole and the second long hole can receive the large load, and the strength against the large load acting in the direction orthogonal to the longitudinal direction of the rack housing can be ensured. Consequently, the strength against the load acting in the longitudinal direction of the rack housing and the strength against the load acting in a direction orthogonal to the longitudinal direction of the rack housing can be improved.

Effect of the Invention

[0021] The steering device according to the present disclosure has an effect of being able to improve the strength against the load acting in the longitudinal direction of the rack housing.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0023] Hereinafter, the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited by the following mode for carrying out the invention (hereinafter referred to as an embodiment). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, substantially the same ones, and those within a so-called equivalent range. Furthermore, the constituent elements disclosed in the following embodiments can be combined as appropriate.

[0024] [First Embodiment] FIG. 1 is a schematic diagram for explaining an electric power steering apparatus 80 according to the first embodiment. In the first embodiment, the electric power steering apparatus 80 is used as an example of a steering apparatus for explanation. As shown in FIG. 1, the electric power steering apparatus 80 includes, in the order in which the force applied from the operator is transmitted, a steering wheel 81, a steering shaft 82, a universal joint 84, an intermediate shaft 85, a universal joint 86, a stub shaft 87, a steering gear 90, and a tie rod 93. The electric power steering apparatus 80 also includes a control device (hereinafter referred to as an ECU (Electronic Control Unit)) 100, a torque sensor 101, and an electric motor 102. A vehicle speed sensor 103 is provided in the vehicle and outputs a vehicle speed signal V to the ECU 100 by CAN (Controller Area Network) communication.

[0025] The steering shaft 82 is connected to the steering wheel 81 at one end and to the universal joint 84 at the other end.

[0026] The intermediate shaft 85 is connected to the universal joint 84 at one end and to the universal joint 86 at the other end. The stub shaft 87 is connected to the universal joint 86 at one end and to the torque sensor 101 at the other end. The torque sensor 101 is connected to the stub shaft 87 at one end and to a first pinion gear 91 of the steering gear 90 at the other end.

[0027] Specifically, the first pinion gear 91 is a shaft-like member having a gear (not shown) formed at an end opposite to the side connected to the stub shaft 87, which meshes with a rack bar 50 described later. The stub shaft 87 and the first pinion gear 91 are connected via a torsion bar (not shown). One end of the torsion bar is connected to the stub shaft 87, and the other end is connected to the first pinion gear 91. The torsion bar transmits rotational torque between the stub shaft 87 and the first pinion gear 91. The first pinion gear 91 rotates by the rotational torque transmitted from the torsion bar. Therefore, in other words, the first pinion gear 91 rotates by the torque input from the steering side.

[0028] The torque sensor 101 is a torque detection device that detects the torque acting on the shaft connected to the torque sensor 101, and detects the rotational torque transmitted between the stub shaft 87 and the first pinion gear 91 via the torsion bar. That is, the stub shaft 87 and the first pinion gear 91 connected via the torsion bar are the shafts to be detected when the torque sensor 101 detects the torque.

[0029] The steering gear 90 includes a first pinion gear 91, a rack bar 50, and a second pinion gear 92. The first pinion gear 91 is connected to the stub shaft 87 via a torsion bar. The rack bar 50 is formed to extend linearly, and the first pinion gear 91 and the second pinion gear 92 mesh with the rack bar 50 at different positions in the linear longitudinal direction of the rack bar 50, respectively.

[0030] Specifically, the rack bar 50 has rack teeth (not shown) formed thereon that mesh with the gear of the first pinion gear 91. Further, on the rack bar 50, rack teeth (not shown) that mesh with the gear (not shown) of the second pinion gear 92 are formed at a position different from the position where the rack teeth that mesh with the first pinion gear 91 are formed in the longitudinal direction of the rack bar 50. For this reason, the rack bar 50 meshes with the second pinion gear 92 at a position different from the position where it meshes with the first pinion gear 91. That is, the rack bar 50 meshes with the second pinion gear 92 at a position closer to one end in the longitudinal direction and meshes with the first pinion gear 91 at a position closer to the other end.

[0031] The second pinion gear 92 rotates by the driving force generated by the electric motor 102. That is, the electric motor 102 is connected to the second pinion gear 92 via a worm reduction gear 94 (see FIG. 2), and the second pinion gear 92 rotates by the driving force transmitted from the electric motor 102. The electric motor 102 rotates the second pinion gear 92 via the worm reduction gear 94. The electric motor 102 is, for example, a brushless motor, but may also be a motor provided with a brush (sliding contact) and a commutator (commutator).

[0032] The steering gear 90 converts the rotational motion transmitted to the first pinion gear 91 and the second pinion gear 92 into a linear motion by the rack bar 50 disposed inside the rack housing 10. The electric power steering apparatus 80 according to the first embodiment is a dual pinion assist system in which the rack bar 50 performs a linear motion by the rotational motion transmitted from the first pinion gear 91 and the second pinion gear 92. The tie rods 93 are respectively connected to both ends in the longitudinal direction of the rack bar 50. That is, the electric power steering apparatus 80 according to the first embodiment is a rack and pinion type electric power steering apparatus 80.

[0033] The torque sensor 101 detects the driver's steering force transmitted to the steering shaft 82 via the steering wheel 81 as steering torque. The vehicle speed sensor 103 detects the traveling speed (vehicle speed) of the vehicle on which the electric power steering device 80 is mounted. The electric motor 102, the torque sensor 101, and the vehicle speed sensor 103 are electrically connected to the ECU 100.

[0034] The ECU 100 controls the operation of the electric motor 102. Also, the ECU 100 acquires signals from the torque sensor 101 and the vehicle speed sensor 103 respectively. That is, the ECU 100 acquires the steering torque T from the torque sensor 101 and the vehicle speed signal V of the vehicle from the vehicle speed sensor 103. The ECU 100 is supplied with electric power from a power supply device (for example, an in-vehicle battery) 105 when the ignition switch 104 is on. The ECU 100 calculates an auxiliary steering command value of an assist command based on the steering torque T and the vehicle speed signal V. Then, the ECU 100 adjusts the power value X supplied to the electric motor 102 based on the calculated auxiliary steering command value. The ECU 100 acquires information on the induced voltage from the electric motor 102 or information output from a rotation detection device such as a resolver provided in the electric motor 102 as operation information Y.

[0035] The steering force of the operator (driver) input to the steering wheel 81 is transmitted to the first pinion gear 91. The steering force transmitted to the first pinion gear 91 is transmitted to the tie rod 93 via the steering gear 90 to displace the wheels.

[0036] Also, the steering force of the operator input to the steering wheel 81 is transmitted to the torque sensor 101 disposed in the transmission path of the steering force from the steering wheel 81 to the first pinion gear 91. At this time, the ECU 100 acquires the steering torque T from the torque sensor 101 and the vehicle speed signal V from the vehicle speed sensor 103. Then, the ECU 100 controls the operation of the electric motor 102. The auxiliary steering torque generated by the electric motor 102 is transmitted to the second pinion gear 92.

[0037] The auxiliary steering torque transmitted to the second pinion gear 92 is transmitted to the tie rod 93 via the steering gear 90 to displace the wheels. That is, the electric power steering apparatus 80 displaces the wheels using, in addition to the steering force of the operator transmitted to the rack bar 50 via the first pinion gear 91, the auxiliary steering torque of the electric motor 102 transmitted to the rack bar 50 via the second pinion gear 92. The electric power steering apparatus 80 according to the first embodiment is thus a dual pinion type electric power steering apparatus in which an assist force is applied to the second pinion gear 92.

[0038] FIG. 2 is a schematic plan view of the rack housing 10 that houses the rack bar 50 shown in FIG. 1. The rack bar 50 (see FIG. 1) is housed in the rack housing 10. The rack housing 10 is formed in a substantially cylindrical shape and houses the rack bar 50 inside. The rack bar 50 is housed inside the cylinder of the rack housing 10 in a direction such that the longitudinal direction of the rack bar 50 is along the axial direction of the cylinder that is the shape of the rack housing 10, or in a direction along the longitudinal direction of the rack housing 10. The rack bar 50 is housed inside the rack housing 10 so as to be movable in the longitudinal direction of the rack bar 50 with respect to the rack housing 10.

[0039] Since the rack bar 50 is housed in the rack housing 10 in a direction such that the longitudinal direction of the rack bar 50 is along the longitudinal direction of the rack housing 10, in the following description, it is described assuming that the longitudinal direction of the rack bar 50 and the longitudinal direction of the rack housing 10 substantially refer to the same direction. That is, it is described that the longitudinal direction of the rack bar 50 is the longitudinal direction of the rack housing 10, and the longitudinal direction of the rack housing 10 is the longitudinal direction of the rack bar 50.

[0040] The tie rods 93 (see FIG. 1) are respectively connected to both ends of the rack bar 50 in the longitudinal direction. Therefore, when the rack bar 50 moves relative to the rack housing 10 in the longitudinal direction, the tie rods 93 also move relative to the rack housing 10 together with the rack bar 50.

[0041] The first pinion gear 91 and the second pinion gear 92 (see FIG. 1) mesh with the rack bar 50 inside the rack housing 10 respectively. The second pinion gear 92 meshes with the rack bar 50 at a position near one end of the rack bar 50 in the longitudinal direction, and the first pinion gear 91 meshes with the rack bar 50 at a position near the other end. Therefore, the first pinion gear 91 and the second pinion gear 92 are arranged at different positions from each other in the longitudinal direction of the rack housing 10.

[0042] Among them, the second pinion gear 92 is connected to a worm reduction gear 94 that transmits the driving force generated by the electric motor 102 to the second pinion gear 92. Therefore, the worm reduction gear 94 is arranged at a position near one end of the rack housing 10 in the longitudinal direction, and the first pinion gear 91 is arranged at a position near the other end. The electric motor 102 is connected to the worm reduction gear 94, and the electric motor 102 is arranged at a distance from the rack housing 10.

[0043] In addition, a plurality of mount portions 20 that are coupled to a vehicle body frame (not shown) by fastening members (not shown) are arranged on the rack housing 10. Mount holes 30 are respectively arranged in the plurality of mount portions 20. Each mount hole 30 is formed as a hole that penetrates the mount portion 20, and it is possible to pass a fastening member through it. Since a bolt is used as the fastening member, the mount hole 30 is a hole through which the bolt used as the fastening member can pass. The plurality of mount portions 20 can couple the rack housing 10 to the vehicle body frame by screwing a bolt and a nut with the bolt passed through the mount hole 30 formed in the mount portion 20 and the fastening hole formed in the vehicle body frame.

[0044] The plurality of mounting portions 20 include a motor-side mounting portion 22 which is a mounting portion 20 arranged closer to one end in the longitudinal direction of the rack housing 10, and a steering-side mounting portion 21 which is a mounting portion 20 arranged closer to the other end in the longitudinal direction of the rack housing 10. The motor-side mounting portion 22 is arranged at a position closer to the electric motor 102 in the longitudinal direction of the rack housing 10, and the steering-side mounting portion 21 is arranged at a position closer to the first pinion gear 91 in the longitudinal direction of the rack housing 10. Here, the position closer to the electric motor 102 in the longitudinal direction refers to the position closer to the portion where the electric motor 102 is indirectly attached to the rack housing 10. In other words, it refers to the position closer to the worm reduction gear 94 in the longitudinal direction, or the position closer to the second pinion gear 92 (see FIG. 1) in the longitudinal direction.

[0045] Among the plurality of mounting portions 20, a plurality of motor-side mounting portions 22 are provided, and the plurality of motor-side mounting portions 22 are respectively arranged on different sides with respect to the rack housing 10 in a direction orthogonal to the longitudinal direction of the rack housing 10. That is, the plurality of motor-side mounting portions 22 are arranged on both sides sandwiching the rack housing 10 in a direction orthogonal to the longitudinal direction of the rack housing 10. In the first embodiment, two motor-side mounting portions 22 are provided, and the two motor-side mounting portions 22 are arranged on opposite sides sandwiching the rack housing 10 in a direction orthogonal to the longitudinal direction of the rack housing 10.

[0046] On the other hand, in the first embodiment, one steering-side mounting portion 21 is arranged on the rack housing 10.

[0047] Each of these mounting portions 20 is provided with a mounting hole 30. Among the mounting holes 30 respectively arranged in the plurality of mounting portions 20, the mounting hole 30 arranged in the motor-side mounting portion 22 is the motor-side mounting hole 32, and the mounting hole 30 arranged in the steering-side mounting portion 21 is the steering-side mounting hole 31. That is, the plurality of mounting holes 30 include a motor-side mounting hole 32 arranged closer to one end in the longitudinal direction of the rack housing 10 and a steering-side mounting hole 31 arranged closer to the other end in the longitudinal direction of the rack housing 10. The motor-side mounting hole 32 is the mounting hole 30 arranged at a position closer to the electric motor 102 in the longitudinal direction of the rack housing 10, and the steering-side mounting hole 31 is the mounting hole 30 arranged at a position closer to the first pinion gear 91 in the longitudinal direction of the rack housing 10.

[0048] The rack housing 10 is coupled to the vehicle body frame 200 of a vehicle equipped with an electric power steering device 80 by a motor-side mounting portion 22 in which the motor-side mounting hole 32 is formed and a steering-side mounting portion 21 in which the steering-side mounting hole 31 is formed as described above.

[0049] Among the motor-side mounting holes 32 respectively arranged in the two motor-side mounting portions 22, one motor-side mounting hole 32 is a reference hole 35 of a round hole that regulates the position of the rack housing 10, and the other motor-side mounting hole 32 is an elongated hole 36 extending in a direction intersecting the longitudinal direction of the rack housing 10.

[0050] The reference hole 35 is a hole having an inner diameter approximately the same as the outer diameter of the bolt and slightly larger than the outer diameter of the bolt. Thereby, the reference hole 35 becomes a hole that can regulate the position of the rack housing 10 by making relative movement with the bolt in the radial direction of the reference hole 35 and the bolt as impossible as possible.

[0051] The reference hole 35 is arranged in the motor side mounting portion 22 on the side closer to the electric motor 102 among the two motor side mounting portions 22. Specifically, as shown in FIG. 2, the electric motor 102 is offset with respect to the rack housing 10 in a direction orthogonal to the longitudinal direction of the rack housing 10 in a plan view of the rack housing 10 in which the two motor side mounting portions 22 are located on both sides of the rack housing 10 with the rack housing 10 interposed therebetween. For this reason, among the two motor side mounting portions 22, one motor side mounting portion 22 is located on the same side as the electric motor 102 in a plan view of the rack housing 10, and the other motor side mounting portion 22 is located on the opposite side of the side where the electric motor 102 is located in a plan view of the rack housing 10.

[0052] The reference hole 35 is arranged in the motor side mounting portion 22 that is located on the same side as the electric motor 102 in a plan view of the rack housing 10 among the two motor side mounting portions 22 arranged in this way. In other words, the electric motor 102 is arranged at the position closest to the reference hole 35 among the plurality of mounting holes 30 arranged in the plurality of mounting portions 20.

[0053] The motor side mounting portion 22 in which the long hole 36 is arranged is the motor side mounting portion 22 that is arranged at a different position from the motor side mounting portion 22 in which the reference hole 35 is arranged in a direction orthogonal to the longitudinal direction of the rack housing 10. For this reason, the long hole 36 is arranged at a position different from the reference hole 35 in a direction orthogonal to the longitudinal direction of the rack housing 10. Further, the long hole 36 extending in a direction intersecting the longitudinal direction of the rack housing 10 is formed as a hole extending in a direction orthogonal to the longitudinal direction of the rack housing 10 in the first embodiment. Furthermore, in the first embodiment, the long hole 36 is arranged at the same position as the reference hole 35 in the longitudinal direction of the rack housing 10.

[0054] The long hole 36 formed in the motor-side mounting portion 22 has a width in a direction orthogonal to the extending direction of the long hole 36 that is the same size as the diameter of the reference hole 35 or slightly larger than the diameter of the reference hole 35. In the first embodiment, since the long hole 36 extends in a direction orthogonal to the longitudinal direction of the rack housing 10, the width of the long hole 36 in the longitudinal direction of the rack housing 10 is the same size as the diameter of the reference hole 35 or slightly larger than the diameter of the reference hole 35. Also, the length of the long hole 36 in the extending direction of the long hole 36 is a length with a margin with respect to the outer diameter of the bolt.

[0055] In a plan view of the rack housing 10, the steering-side mounting portion 21 is located on the same side of the rack housing 10 in a direction orthogonal to the longitudinal direction of the rack housing 10 as the motor-side mounting portion 22 where the reference hole 35 is disposed. That is, in a plan view of the rack housing 10, the steering-side mounting portion 21 is located on the opposite side of the rack housing 10 in a direction orthogonal to the longitudinal direction of the rack housing 10 from the side where the motor-side mounting portion 22 where the long hole 36 is disposed is located.

[0056] The steering-side mounting hole 31 formed in the steering-side mounting portion 21 is a large-diameter hole 37 of a round hole having a diameter larger than the diameter of the reference hole 35. That is, the large-diameter hole 37 formed in the steering-side mounting portion 21 has a size within a range that allows the steering-side mounting portion 21 and the vehicle body frame to be fastened by bolts, and is a round hole having a diameter with a margin with respect to the outer diameter of the bolt.

[0057] In addition, the diameter of the large-diameter hole 37 formed in the steering-side mounting portion 21 is larger than the width of the long hole 36 in the direction orthogonal to the extending direction of the long hole 36 formed in the motor-side mounting portion 22. For this reason, the long hole 36 formed in the motor-side mounting portion 22 has a width in the direction orthogonal to the extending direction of the long hole 36 that is equal to or greater than the diameter of the reference hole 35 formed in the motor-side mounting portion 22 and is smaller than the longitudinal dimension of the rack housing 10 in the steering-side mounting hole 31 formed in the steering-side mounting portion 21. Regarding the size relationship among the diameter of the reference hole 35 which is the motor-side mounting hole 32, the width of the long hole 36 which is the motor-side mounting hole 32, and the diameter of the large-diameter hole 37 which is the steering-side mounting hole 31, these mounting holes 30 have a size relationship of reference hole 35 diameter ≤ long hole 36 width < large-diameter hole 37 diameter.

[0058] Next, a procedure for attaching the rack housing 10 to the vehicle body frame will be described. FIG. 3 is an explanatory diagram of the attachment method when attaching the rack housing 10 to the vehicle body frame. When attaching the rack housing 10 to the vehicle body frame, it is performed with the rack bar 50 accommodated in the rack housing 10 and the steering gear 90 and the electric motor 102 attached. The rack housing 10 is attached to the vehicle body frame in a direction in which the longitudinal direction of the rack housing 10 is along the vehicle width direction.

[0059] The attachment of the rack housing 10 to the vehicle body frame is first performed by passing a bolt through the reference hole 35 formed in the motor-side mounting portion 22 and also through the fastening hole on the vehicle body frame side to position the rack housing 10. That is, the reference hole 35 is used as the positioning mounting hole 30 for the rack housing 10, and the reference hole 35 is positioned with respect to the vehicle body frame (see the dashed line in FIG. 3). At the stage of positioning the reference hole 35, the bolt and nut passed through the reference hole 35 are temporarily fixed or the nut is not attached to the bolt.

[0060] When positioning the vehicle body frame by passing a bolt through the reference hole 35, the rack housing 10 is rotated about the reference hole 35 (see the arrow in FIG. 3), aligning the long hole 36 formed in the motor side mount portion 22 and the large diameter hole 37 formed in the steering side mount portion 21 with the positions of the fastening holes on the vehicle body frame side. After aligning the long hole 36 and the large diameter hole 37 with the positions of the fastening holes on the vehicle body frame side, bolts are passed through the long hole 36, the large diameter hole 37, and the fastening holes on the vehicle body frame side.

[0061] At that time, since the large diameter hole 37 arranged at a position with a large distance from the reference hole 35 has a diameter larger than the diameter of the reference hole 35, the bolt can be easily passed through. That is, when the distance from the reference hole 35 is large, the relative dimensional error with respect to the reference hole 35 tends to be large, but since the diameter of the large diameter hole 37 is larger than the diameter of the reference hole 35, the dimensional error with respect to the reference hole 35 can be absorbed and the bolt can be easily passed through.

[0062] After passing bolts through each mounting hole 30 and the fastening holes on the vehicle body frame side, the bolts and nuts, which are fastening members, are tightened. Thereby, each mount portion 20 of the rack housing 10 and the vehicle body frame are coupled, and the rack housing 10 is attached to the vehicle body frame.

[0063] Next, the operation of the electric power steering device 80 will be described. When the steering wheel 81 is operated during the operation of a vehicle equipped with the electric power steering device 80, the steering force applied to the steering wheel 81 is transmitted from the steering wheel 81 to the steering shaft 82. The steering force transmitted to the steering shaft 82 is transmitted as a steering torque from the steering shaft 82 to the intermediate shaft 85, and from the intermediate shaft 85 to the first pinion gear 91 via the stub shaft 87. Thereby, the steering gear 90 having the first pinion gear 91 converts the rotational motion transmitted from the first pinion gear 91 into a linear motion of the rack bar 50 and operates the tie rod 93.

[0064] In addition, the electric power steering apparatus 80 according to the first embodiment has an electric motor 102 that generates an auxiliary steering torque for assisting the driver's steering. The electric motor 102 generates an auxiliary steering torque based on the steering torque detected by a torque sensor 101 disposed between a stub shaft 87 and a first pinion gear 91.

[0065] The torque sensor 101 detects the steering torque applied to the stub shaft 87 based on the angle of relative rotation when the stub shaft 87 and the first pinion gear 91 rotate relative to each other. That is, since the stub shaft 87 and the first pinion gear 91 are connected via a torsion bar (not shown), when a steering torque is applied to the stub shaft 87, the steering torque is transmitted between the stub shaft 87 and the first pinion gear 91 via the torsion bar. At this time, the torsion bar is slightly twisted, causing the stub shaft 87 and the first pinion gear 91 to rotate relative to each other. The torque sensor 101 detects the relative rotation between the stub shaft 87 and the first pinion gear 91 due to the slight twisting of the torsion bar and transmits it to the ECU 100 as an electrical signal.

[0066] The ECU 100 operates the electric motor 102 based on the electrical signal transmitted from the torque sensor 101 and causes the electric motor 102 to generate an auxiliary steering torque. That is, the electrical signal transmitted from the torque sensor 101 to the ECU 100 changes based on the steering torque T acting between the stub shaft 87 and the first pinion gear 91. For this reason, the ECU 100 uses the electrical signal transmitted from the torque sensor 101 as information that changes according to the steering torque T acting on the stub shaft 87 and the first pinion gear 91, adjusts the power value X supplied to the electric motor 102 based on the electrical signal transmitted from the torque sensor 101, and causes the electric motor 102 to generate an auxiliary steering torque.

[0067] That is, the ECU 100 acquires the signal of the steering torque T from the torque sensor 101, acquires the vehicle speed signal V of the vehicle from the vehicle speed sensor 103, and further acquires the operation information Y of the electric motor 102 from the rotation detection device provided on the electric motor 102, and generates an auxiliary steering torque for the electric motor 102 based on these operation information Y, the steering torque T, and the vehicle speed signal V. The auxiliary steering torque generated by the electric motor 102 is transmitted to the second pinion gear 92. The steering gear 90 having the second pinion gear 92 converts the rotational motion transmitted from the second pinion gear 92 into the linear motion of the rack bar 50. Thereby, the steering force applied by the driver to the steering wheel 81 is assisted by the auxiliary steering torque generated by the electric motor 102.

[0068] Specifically, when the driver steers the steering wheel 81, the stub shaft 87 and the first pinion gear 91 rotate by the transmission of the steering force. When the first pinion gear 91 rotates, the steering torque of the first pinion gear 91 is transmitted from the first pinion gear 91 to the rack teeth (not shown) of the rack bar 50 that meshes with the first pinion gear 91. Thereby, the rack bar 50 linearly moves in the axial direction while being supported by the rack housing 10.

[0069] In addition, the driving force generated by the electric motor 102 is transmitted to the second pinion gear 92 via the worm reduction gear 94, and the second pinion gear 92 rotates by the driving force generated by the electric motor 102. When the second pinion gear 92 rotates, the auxiliary steering torque of the second pinion gear 92 is transmitted from the second pinion gear 92 to the rack teeth (not shown) of the rack bar 50 that meshes with the second pinion gear 92. Thereby, the rack bar 50 linearly moves while the linear motion due to the steering torque from the first pinion gear 91 is assisted by the auxiliary steering torque from the second pinion gear 92.

[0070] The linear motion of the rack bar 50 is transmitted to the tie rods 93 respectively connected to both ends on both sides in the longitudinal direction of the rack bar 50, and the direction of the wheels is changed as the tie rods 93 move. That is, the tie rods 93 to which the linear motion of the rack bar 50 is transmitted move in the substantially width direction of the vehicle according to the direction of the linear motion of the rack bar 50, thereby changing the direction of the vehicle used as the steering wheels.

[0071] When the driver steers the steering wheel 81, in addition to the steering torque by the driver's operation as described above, the tie rod 93 is linearly moved by the auxiliary steering torque by the driving force generated by the electric motor 102 to change the direction of the wheels. That is, when the steering wheel 81 is steered, the electric motor 102 which is the power source of the auxiliary steering torque operates to generate a driving force.

[0072] The electric power steering device 80 mounted on the vehicle operates as described above. However, during the running of the vehicle, a large load may act on the wheels due to, for example, the wheels colliding with a curbstone due to a driving mistake. When a large load acts on the wheels, the load is transmitted to the rack bar 50 via the tie rod 93, and is transmitted from the rack bar 50 to the rack housing 10 via the first pinion gear 91 and the second pinion gear 92.

[0073] Since the rack bar 50 and the rack housing 10 are arranged in such a direction that the longitudinal direction of the rack bar 50 and the rack housing 10 is along the width direction of the vehicle, the large load transmitted from the wheel side acts as a load acting in the longitudinal direction of the rack housing 10 on the rack housing 10. That is, the large load transmitted to the rack housing 10 via the tie rod 93, the rack bar 50, etc. from the wheel acts as a lateral load Fx which is a load acting in the direction along the longitudinal direction of the rack housing 10 on the rack housing 10.

[0074] When a large lateral load Fx acts on the rack housing 10, the contact surfaces between the mounting portion 20 of the rack housing 10 and the vehicle body frame may shift relative to each other in the longitudinal direction of the rack housing 10 due to the lateral load Fx. When the contact surfaces between the mounting portion 20 of the rack housing 10 and the vehicle body frame shift relative to each other, the mounting holes 30 formed in the mounting portion 20 will shift in the longitudinal direction of the rack housing 10 with respect to the bolts that fasten the rack housing 10 to the vehicle body frame.

[0075] When the mounting holes 30 formed in the mounting portion 20 shift with respect to the bolts, some of the plurality of mounting holes 30 formed in the plurality of mounting portions 20 will come into contact with the bolts. In the first embodiment, among the plurality of mounting holes 30, the mounting hole 30 with the smallest size in the longitudinal direction of the rack housing 10 is the reference hole 35 formed in the motor-side mounting portion 22. Therefore, when the rack housing 10 shifts in the longitudinal direction due to the lateral load Fx, the inner peripheral surface of the reference hole 35 will come into contact with the bolt.

[0076] In addition, the elongated holes 36 formed in the motor-side mounting portion 22 different from the motor-side mounting portion 22 where the reference hole 35 is formed have the same size as the reference hole 35 or are slightly larger than the reference hole 35 in the longitudinal direction of the rack housing 10, and the size in the longitudinal direction of the rack housing 10 is smaller than that of the steering-side mounting hole 31. For this reason, when a large lateral load Fx acts on the rack housing 10 and the rack housing 10 shifts in the longitudinal direction of the rack housing 10 with respect to the bolts that fasten the rack housing 10 to the vehicle body frame, the inner peripheral surfaces of the elongated holes 36 formed in the motor-side mounting portion 22 will also come into contact with the bolts.

[0077] Therefore, when a large lateral load Fx acts on the rack housing 10, the rack housing 10 can receive the large lateral load Fx by the reference holes 35 and the long holes 36 formed in the motor-side mount portion 22 and the bolts passed through these motor-side mount holes 32. Thereby, even when a large lateral load Fx acts on the rack housing 10, the lateral load Fx can be received by the two bolts, so that the strength against the lateral load Fx can be ensured. For this reason, even when a large lateral load Fx acts on the rack housing 10, damage to the bolts and the mount portion 20 can be suppressed, and the running of the vehicle can be continued.

[0078] As described above, the plurality of mount holes 30 included in the plurality of mount portions 20 disposed in the rack housing 10 of the electric power steering apparatus 80 according to the first embodiment have a motor-side mount hole 32 and a steering-side mount hole 31. The motor-side mount hole 32 has a reference hole 35 that regulates the position of the rack housing 10 and a long hole 36 that extends in a direction intersecting the longitudinal direction of the rack housing 10. Among these, the long hole 36 has a width in a direction orthogonal to the extending direction of the long hole 36 that is equal to or greater than the diameter of the reference hole 35 and smaller than the size of the rack housing 10 in the longitudinal direction in the steering-side mount hole 31.

[0079] For this reason, when the rack housing 10 receives a large lateral load Fx and the contact surface between the mount portion 20 and the vehicle body frame is displaced in the longitudinal direction of the rack housing 10, the two mount holes 30 of the reference hole 35 and the long hole 36 can be brought into contact with the bolts that are fastening members. Thereby, when the rack housing 10 receives a large lateral load Fx, the large lateral load Fx can be received by the two bolts passed through the reference hole 35 and the long hole 36, and the strength against the large load acting in the longitudinal direction of the rack housing 10 can be ensured. As a result, the strength against the load acting in the longitudinal direction of the rack housing 10 can be improved.

[0080] Further, among the plurality of motor-side mounting holes 32, the long hole 36 extends in a direction orthogonal to the longitudinal direction of the rack housing 10. Therefore, when a large load acting in the longitudinal direction of the rack housing 10 acts on the rack housing 10, it is possible to easily bring the long hole 36 into contact with the bolt, which is a fastening member. As a result, when the rack housing 10 receives a large lateral load Fx, in addition to the bolt passed through the reference hole 35, the bolt passed through the long hole 36 can also easily receive the large lateral load Fx, ensuring the strength against the large load acting in the longitudinal direction of the rack housing 10. Consequently, the strength against the load acting in the longitudinal direction of the rack housing 10 can be improved.

[0081] Further, since the long hole 36 among the plurality of motor-side mounting holes 32 is arranged at the same position as the reference hole 35 in the longitudinal direction of the rack housing 10, the distance between the long hole 36 and the reference hole 35 can be minimized as much as possible. As a result, the relative dimensional error between the long hole 36 and the reference hole 35 can be minimized, so that the width in the direction orthogonal to the extending direction of the long hole 36, that is, the width of the long hole 36 in the longitudinal direction of the rack housing 10, can be minimized as much as possible. For this reason, when a large lateral load Fx acts on the rack housing 10, it is possible to easily bring the long hole 36 into contact with the bolt. In addition to the bolt passed through the reference hole 35, the bolt passed through the long hole 36 can also easily receive the large lateral load Fx. Thus, when a large lateral load Fx acts on the rack housing 10, the two bolts passed through the reference hole 35 and the long hole 36 can receive the large lateral load Fx, ensuring the strength against the large load acting in the longitudinal direction of the rack housing 10. Consequently, the strength against the load acting in the longitudinal direction of the rack housing 10 can be improved.

[0082] In addition, since the electric motor 102 is disposed at the position closest to the reference hole 35 among the plurality of mounting holes 30, when the rack housing 10 is attached to the vehicle body frame while positioning it at the reference hole 35 by passing a bolt through the reference hole 35, the force required to rotate the rack housing 10 about the reference hole 35 can be reduced. That is, by disposing the heavy electric motor 102 at a position close to the reference hole 35, the rack housing 10 can be rotated with a relatively small force when rotating the rack housing 10 about the reference hole 35. Thereby, the labor required when attaching the rack housing 10 to the vehicle body frame can be reduced, and the rack housing 10 can be easily attached to the vehicle body frame. As a result, the assemblability of the rack housing 10 can be improved.

[0083] In addition, since the steering side mounting hole 31 has a large diameter hole 37 which is a round hole having a diameter larger than the diameter of the reference hole 35, the assemblability when attaching the rack housing 10 to the vehicle body frame can be ensured. That is, since the steering side mounting hole 31 is located at a distance from the reference hole 35, the relative dimensional error of the steering side mounting hole 31 with respect to the reference hole 35 tends to be large. For this reason, since the steering side mounting hole 31 has the large diameter hole 37 having a diameter larger than that of the reference hole 35, even when the relative dimensional error of the large diameter hole 37 with respect to the reference hole 35 is large when attaching the rack housing 10 to the vehicle body frame, a bolt can be passed through the large diameter hole 37 and through the fastening hole formed in the vehicle body frame. Thereby, when attaching the rack housing 10 to the vehicle body frame, a bolt can be easily passed through the steering side mounting hole 31 which is located at a distance from the reference hole 35, and the rack housing 10 can be easily attached to the vehicle body frame. As a result, the assemblability of the rack housing 10 can be improved.

[0084] [Second Embodiment] Next, the electric power steering apparatus 80 according to the second embodiment will be described. The same reference numerals are given to the same constituent parts as those in the first embodiment, and the description thereof will be omitted. Hereinafter, the description will be centered on the differences from the first embodiment.

[0085] FIG. 4 is a schematic plan view of a rack housing 10 included in an electric power steering apparatus 80 according to a second embodiment. In the electric power steering apparatus 80 according to the second embodiment, as in the first embodiment, the rack housing 10 has a motor-side mount hole 32 formed in a motor-side mount portion 22, and the motor-side mount hole 32 has a reference hole 35 and a long hole 36. On the other hand, unlike the first embodiment, a steering-side mount hole 31 formed in a steering-side mount portion 21 has a second long hole 38 extending in a direction along the longitudinal direction of the rack housing 10. Similar to the first embodiment, the steering-side mount portion 21 having the second long hole 38 is disposed on the same side of the rack housing 10 as the motor-side mount portion 22 where the reference hole 35 is disposed in a direction orthogonal to the longitudinal direction of the rack housing 10 in a plan view of the rack housing 10.

[0086] The second long hole 38 extending in a direction along the longitudinal direction of the rack housing 10 has a width in a direction orthogonal to the extending direction of the second long hole 38 that is larger than the width in a direction orthogonal to the extending direction of the long hole 36 in the long hole 36 formed in the motor-side mount portion 22. That is, the second long hole 38 has a width in a direction orthogonal to the longitudinal direction of the rack housing 10 that is larger than the width of the long hole 36 in the longitudinal direction of the rack housing 10.

[0087] Further, the second long hole 38 has a length in the extending direction of the second long hole 38 that provides a margin with respect to the outer diameter of the bolt. Therefore, when comparing the second long hole 38 and the long hole 36, the long hole 36 formed in the motor-side mount hole 32 has a width in a direction orthogonal to the extending direction of the long hole 36 that is smaller than the size in the longitudinal direction of the rack housing 10 in the second long hole 38 formed in the steering-side mount portion 21. Accordingly, regarding the size relationship among the diameter of the reference hole 35 which is the motor-side mount hole 32, the width of the long hole 36 which is the motor-side mount hole 32, and the length of the second long hole 38 which is the steering-side mount hole 31, these mount holes 30 have a size relationship of reference hole 35 diameter ≤ long hole 36 width < second long hole 38 length.

[0088] When attaching the rack housing 10 formed in this way to the vehicle body frame, as in the first embodiment, first, pass a bolt through the reference hole 35 formed in the motor side mount portion 22, and use the reference hole 35 to position it with respect to the vehicle body frame. After positioning the reference hole 35, by rotating the rack housing 10 around the reference hole 35, the elongated hole 36 formed in the motor side mount portion 22 and the second elongated hole 38 formed in the steering side mount portion 21 are aligned with the positions of the fastening holes on the vehicle body frame side. After aligning the elongated hole 36 and the second elongated hole 38 with the positions of the fastening holes on the vehicle body frame side, pass bolts through the elongated hole 36, the second elongated hole 38, and the fastening holes on the vehicle body frame side.

[0089] At that time, the second elongated hole 38 arranged at a position with a large distance from the reference hole 35 has a length that is sufficient with respect to the outer diameter of the bolt and a width that is larger than the width of the elongated hole 36, so the bolt can be easily passed through. That is, when the distance from the reference hole 35 is large, the relative dimensional error with respect to the reference hole 35 tends to be large, but since the width of the second elongated hole 38 is larger than the width of the elongated hole 36, the dimensional error with respect to the reference hole 35 can be absorbed and the bolt can be easily passed through. After passing bolts through each mount hole 30 and the fastening holes on the vehicle body frame side, tighten the bolt and nut, which are fastening members, to attach the rack housing 10 to the vehicle body frame.

[0090] During the running of a vehicle with the rack housing 10 attached to the vehicle body frame as described above, a large load may act on the wheels due to, for example, a driving mistake causing the wheels to collide with a curb. When a large load acts on the wheels, the load is transmitted to the rack housing 10 via the tie rod 93, the rack bar 50, etc. As the load acting on the rack housing 10, a lateral load Fx along the vehicle width direction mainly acts. However, when a large lateral load Fx acts on the rack housing 10, similar to the first embodiment, a reference hole 35 and a long hole 36 formed in the motor side mount portion 22, and bolts passed through these mount holes 30 can receive the large lateral load Fx.

[0091] Also, when a large load acts on the wheels due to, for example, the wheels colliding with a curb during the running of the vehicle, in addition to the lateral load Fx along the vehicle width direction, a longitudinal load Fy, which is a load acting in the direction along the vehicle traveling direction, may also act. The longitudinal load Fy along the vehicle traveling direction acts on the rack housing 10 as a load in a direction orthogonal to the longitudinal direction of the rack housing 10.

[0092] When a large longitudinal load Fy acts on the rack housing 10, the contact surfaces between the mount portion 20 of the rack housing 10 and the vehicle body frame may shift from each other in a direction orthogonal to the longitudinal direction of the rack housing 10 due to the longitudinal load Fy. When the contact surfaces between the mount portion 20 of the rack housing 10 and the vehicle body frame shift from each other, the mount holes 30 formed in the mount portion 20 shift in a direction orthogonal to the longitudinal direction of the rack housing 10 with respect to the bolts fastening the rack housing 10 to the vehicle body frame.

[0093] When the mounting holes 30 formed in the mounting portion 20 are displaced with respect to the bolts, among the plurality of mounting holes 30 formed in the plurality of mounting portions 20, some of the mounting holes 30 abut against the bolts. In the second embodiment, among the plurality of mounting holes 30, the reference hole 35 formed in the motor side mounting portion 22 is the mounting hole 30 having the smallest size in the direction orthogonal to the longitudinal direction of the rack housing 10. Therefore, when the rack housing 10 is displaced in the direction orthogonal to the longitudinal direction by the vertical load Fy, the inner peripheral surface of the reference hole 35 abuts against the bolt.

[0094] Further, the second long hole 38 formed in the steering side mounting portion 21 has a size in the direction orthogonal to the longitudinal direction of the rack housing 10 that is smaller than the size in the direction orthogonal to the longitudinal direction of the rack housing 10 in the long hole 36 formed in the motor side mounting portion 22. For this reason, when a large vertical load Fy acts on the rack housing 10 and the rack housing 10 is displaced in the direction orthogonal to the longitudinal direction of the rack housing 10 with respect to the bolts that fasten the rack housing 10 to the vehicle body frame, the inner peripheral surface of the second long hole 38 formed in the steering side mounting portion 21 also abuts against the bolt.

[0095] Therefore, when a large vertical load Fy acts on the rack housing 10, the rack housing 10 can receive the large vertical load Fy by the reference hole 35 formed in the motor side mounting portion 22, the second long hole 38 formed in the steering side mounting portion 21, and the bolts passed through these mounting holes 30. As a result, even when a large vertical load Fy acts on the rack housing 10, the vertical load Fy can be received by the two bolts, so that the strength against the vertical load Fy can be ensured. For this reason, even when a large vertical load Fy acts on the rack housing 10, damage to the bolts and the mounting portion 20 can be suppressed, and the vehicle can continue to run.

[0096] As described above, in the electric power steering apparatus 80 according to the second embodiment, the steering-side mount hole 31 formed in the steering-side mount portion 21 has an elongated hole-shaped second elongated hole 38 extending in a direction along the longitudinal direction of the rack housing 10. Therefore, when the rack housing 10 receives a large vertical load Fy and the contact surface between the mount portion 20 and the vehicle body frame is displaced in a direction orthogonal to the longitudinal direction of the rack housing 10, the two mount holes 30, i.e., the reference hole 35 and the second elongated hole 38, can be brought into contact with bolts which are fastening members. As a result, when the rack housing 10 receives a large vertical load Fy, the two bolts passed through the reference hole 35 and the second elongated hole 38 can receive the large vertical load Fy, and the strength against a large load acting in a direction orthogonal to the longitudinal direction of the rack housing 10 can be ensured. Consequently, the strength against the load acting in the longitudinal direction of the rack housing 10 and the strength against the load acting in a direction orthogonal to the longitudinal direction of the rack housing 10 can be improved.

[0097] [Modification Example] In addition, in the first embodiment described above, the elongated hole 36 formed in the motor-side mount portion 22 different from the reference hole 35 is arranged at the same position as the reference hole 35 in the longitudinal direction of the rack housing 10, but the elongated hole 36 may be arranged at a position displaced from the reference hole 35.

[0098] FIG. 5 is a schematic plan view of the rack housing 10 in a case where the elongated hole 36 is arranged at a position displaced from the reference hole 35, which is a modification example of the electric power steering apparatus 80 according to the first embodiment. As shown in FIG. 5, the reference hole 35 and the elongated hole 36 arranged in the two motor-side mount portions 22 of the rack housing 10 may be arranged at different positions in the longitudinal direction of the rack housing 10. That is, the motor-side mount portion 22 in which the reference hole 35 is formed and the motor-side mount portion 22 in which the elongated hole 36 is formed may be arranged at different positions in the longitudinal direction of the rack housing 10.

[0099] The elongated hole 36 is preferably arranged such that the distance from the reference hole 35 is minimized within a range according to the shape of the rack housing 10 and the shape around the portion where the rack housing 10 is attached. The elongated hole 36 may be arranged at a position where the distance from the reference hole 35 is minimized considering the form around the elongated hole 36, even if the position of the rack housing 10 in the longitudinal direction is not exactly the same as the position of the reference hole 35.

[0100] Also, in the above-described first embodiment and second embodiment, three mount portions 20 are arranged on the rack housing 10, but the number of mount portions 20 arranged on the rack housing 10 may be other than three.

[0101] Figs. 6 and 7 are schematic plan views of a rack housing 10 having a steering-side mount portion 21 in which a large-diameter hole 37 is formed and a steering-side mount portion 21 in which a second elongated hole 38 is formed, which are modified examples of the electric power steering apparatus 80 according to the second embodiment. The mount portion 20 arranged on the rack housing 10 may have two steering-side mount portions 21, or may have a total of four mount portions 20 including two motor-side mount portions 22. In this case, as shown in Figs. 6 and 7, it is preferable that a second elongated hole 38 is formed in one of the two steering-side mount portions 21, and a large-diameter hole 37 is formed in the other steering-side mount portion 21.

[0102] The second elongated hole 38 and the large-diameter hole 37 may be, for example, as shown in Fig. 6, in a direction orthogonal to the longitudinal direction of the rack housing 10 in a plan view of the rack housing 10, the second elongated hole 38 is located on the same side as the reference hole 35 with respect to the rack housing 10, and the large-diameter hole 37 is located on the same side as the elongated hole 36 with respect to the rack housing 10. Or, as shown in Fig. 7, in a plan view of the rack housing 10, in a direction orthogonal to the longitudinal direction of the rack housing 10, the large-diameter hole 37 is located on the same side as the reference hole 35 with respect to the rack housing 10, and the second elongated hole 38 is located on the same side as the elongated hole 36 with respect to the rack housing 10.

[0103] The mounting portion 20 of the rack housing 10 has a plurality of steering-side mounting portions 21 and a plurality of steering-side mounting holes 31, so that the number of bolts used as fastening members can be increased, and the force for coupling the mounting portion 20 to the vehicle body frame by the bolts can be increased. Thereby, even when a large load acts on the rack housing 10, it is possible to suppress the contact surface between the mounting portion 20 and the vehicle body frame from shifting due to the acting load, and the strength against the load acting on the rack housing 10 can be ensured.

[0104] Also, in the above-described first embodiment, second embodiment, and modification, although the electric power steering device 80 has been described as an example of the steering device, the steering device in which the mounting holes 30 arranged in the mounting portion 20 of the rack housing 10 are formed in the above-described form may be other than the electric power steering device 80. The steering device having the rack housing 10 in which the mounting holes 30 are formed in the above-described form may be, for example, a hydraulic power steering device, and the type of the steering device does not matter.

[0105] As described above, the preferred embodiments of the present disclosure have been described, but the present disclosure is not limited to those described in the above embodiments. The configurations described as embodiments or modifications may be combined as appropriate.

Explanation of Reference Numerals

[0106] 10 Rack housing 20 Mounting portion 21 Steering-side mounting portion 22 Motor-side mounting portion 30 Mounting hole 31 Steering-side mounting hole 32 Motor-side mounting hole 35 Reference hole 36 Long hole 37 Large-diameter hole 38 Second long hole 50 Rack bar 80 Electric power steering device 81 Steering wheel 82 Steering Shaft 84, 86 Universal Joint 85 Intermediate Shaft 87 Stub Shaft 90 Steering Gear 91 First Pinion Gear 92 Second Pinion Gear 93 Tie Rod 94 Worm Reduction Gear 100 ECU 101 Torque Sensor 102 Electric Motor 103 Vehicle Speed Sensor 104 Ignition Switch 105 Power Supply

Claims

1. A rack bar extending linearly, a rack housing for accommodating the rack bar, a plurality of mount portions disposed in the rack housing, a plurality of mount holes through which fastening members for coupling the rack housing to the vehicle body frame pass, each of the plurality of mount portions having one, comprising: The plurality of mount holes are a mount hole disposed near one end in the longitudinal direction of the rack housing, and a mount hole disposed near the other end in the longitudinal direction of the rack housing, The mount hole disposed near the one end is a reference hole of a round hole that regulates the position of the rack housing, and has an elongated hole disposed at a position different from the reference hole in a direction orthogonal to the longitudinal direction of the rack housing and extending in a direction intersecting the longitudinal direction of the rack housing, The elongated hole has a width in a direction orthogonal to the extending direction of the elongated hole that is equal to or greater than the diameter of the reference hole and smaller than the size of the rack housing in the longitudinal direction in the mount hole disposed near the other end. A steering device.

2. The steering device according to claim 1, wherein the elongated hole extends in a direction orthogonal to the longitudinal direction of the rack housing.

3. The steering device according to claim 1 or 2, wherein the elongated hole is disposed at the same position as the reference hole in the longitudinal direction of the rack housing.

4. On the rack bar, a first pinion gear that rotates by torque input from the steering side and a second pinion gear that rotates by a driving force generated by an electric motor mesh with each other at different positions in the longitudinal direction of the rack bar, The steering device according to claim 1 or 2, wherein the electric motor is disposed at a position closest to the reference hole among the plurality of the mounting holes.

5. The steering device according to claim 1 or 2, wherein the mounting hole disposed closer to the other end has a large-diameter hole which is a round hole having a diameter larger than the diameter of the reference hole.

6. The steering device according to claim 1 or 2, wherein the mounting hole disposed closer to the other end has a second elongated hole which is an elongated hole extending in a direction along the longitudinal direction of the rack housing.

Images