WO2023157961A1

WO2023157961A1 - Steering device

Info

Publication number: WO2023157961A1
Application number: PCT/JP2023/005881
Authority: WO
Inventors: 敦吉武; 直也杉本
Original assignee: クノールブレムゼステアリングシステムジャパン株式会社
Priority date: 2022-02-21
Filing date: 2023-02-20
Publication date: 2023-08-24
Also published as: JPWO2023157961A1

Abstract

A steering device comprises a steering shaft (1), a sector gear (5) positioned radially outward of the steering shaft (1), an intermediate shaft (2) positioned on the side opposite from the steering shaft (1) with the sector gear (5) therebetween, first and second bevel gears (42, 43) connecting the steering shaft (1) and the intermediate shaft (2), a torque sensor (8) that detects steering torque accompanying rotational force, a first electric motor (6) that imparts torque for rotational force, and a ball screw mechanism (4) that transmits thrust generated by the rotational force to the sector gear (5). The intermediate shaft (2) is provided so as to be inclined at an inclination angle (α) with respect to the steering shaft (1) by the first and second bevel gears (42, 43). The torque sensor (8) and the first electric motor (6) are provided to the steering shaft (1), and the ball screw mechanism (4) is provided to the intermediate shaft (2).

Description

steering device

The present invention relates to steering devices.

As a steering device, for example, a steering device described in Patent Document 1 below is known.

The steering device of Patent Literature 1 has a steering shaft to which a rotational force due to a driver's steering operation is input. The steering shaft is provided with a torque sensor for detecting steering torque, an electric motor for applying assist torque to the rotational force, and a ball screw mechanism for transmitting thrust generated by the rotational force to the output shaft.

In the steering device described in Patent Document 1, since the torque sensor, the electric motor and the ball screw mechanism are provided on the steering shaft, the steering device becomes large in the axial direction. It may be difficult to apply.

SUMMARY OF THE INVENTION The present invention has been devised in view of the conventional circumstances, and one object of the present invention is to provide a steering device capable of reducing the axial dimension of the steering device.

JP 2019-156082 A

In the present invention, as one aspect of the steering device, the steering device includes a first shaft, an output shaft positioned radially outside the first shaft, and a second shaft positioned on the opposite side of the first shaft across the output shaft. a gear mechanism connecting a first shaft and a second shaft; a torque sensor; an electric motor; , and the remaining one is provided on the second shaft.

According to the present invention, the axial dimension of the steering device can be reduced.

1 is a top view of the steering device of the first embodiment; FIG. FIG. 2 is a longitudinal sectional view of the steering device of the first embodiment taken along line AA in FIG. 1; 1 is a perspective view of a steering device according to a first embodiment; FIG. It is a top view of the steering device of a 2nd embodiment. FIG. 5 is a longitudinal cross-sectional view of the second embodiment of the steering device taken along line BB of FIG. 4; It is a top view of the steering device of 3rd Embodiment. FIG. 7 is a vertical cross-sectional view of the steering device of the third embodiment taken along line CC of FIG. 6; It is a top view of the steering device of a 4th embodiment. FIG. 9 is a vertical cross-sectional view of the fourth embodiment of the steering device taken along line DD of FIG. 8; FIG. 9 is a partial cross-sectional view of the first electric motor, etc., taken along line EE in FIG. 8;

An embodiment of the steering device of the present invention will be described below with reference to the drawings. In the present invention, the steering device has a first shaft that is one of the steering shaft 1 and the intermediate shaft 2, and a second shaft that is the other of the steering shaft 1 and the intermediate shaft 2, and the torque sensor 8. Two of the first electric motor 6 and the ball screw mechanism 4 are provided on the first shaft, and the remaining one is provided on the second shaft. In other words, in the present invention, the steering device has a first shaft that is one of the steering shaft 1 and the intermediate shaft 2 and a second shaft that is the other of the steering shaft 1 and the intermediate shaft 2, All of the torque sensor 8, the first electric motor 6 and the ball screw mechanism 4 are prevented from being provided on the first shaft or the second shaft.

[First Embodiment]
(Structure of steering device)
FIG. 1 is a top view of the steering device of the first embodiment. 2 is a longitudinal sectional view of the steering apparatus of the first embodiment taken along line AA of FIG. 1. FIG. In FIG. 2, the side (upper side in the figure) linked to the steering wheel in the direction along the rotation axis P of the steering shaft 1 is defined as "one end", and the side (lower side in the figure) to which the first bevel gear 42 is attached. is described as "the other end". In addition, in FIG. 2, for the sake of simplification, cross-sections of the first electric motor 6 and the first EPS controller 48 are omitted. FIG. 3 is a perspective view of the steering device of the first embodiment.

In the first embodiment, the steering shaft 1 is the first shaft and the intermediate shaft 2 is the second shaft, and the torque sensor 8 and the first electric motor 6 are provided on the steering shaft 1, On the other hand, an example in which the ball screw mechanism 4 is provided on the intermediate shaft 2 is shown.

The steering device includes a steering shaft 1 linked to a steering wheel (not shown), an intermediate shaft 2 arranged radially outside the steering shaft 1, and a gear mechanism 3 connecting the steering shaft 1 and the intermediate shaft 2. , a ball screw mechanism 4 provided on the intermediate shaft 2 , a sector gear (output shaft) 5 to which thrust from the ball screw mechanism 4 is transmitted and used to steer the steerable wheels, and an assist torque to the steering shaft 1 . It is mainly composed of a first electric motor 6, a first speed reducer 7 that reduces the rotation of the first electric motor 6, and a torque sensor 8 that detects the steering torque associated with the rotational force input from the driver. ing.

The steering shaft 1 is housed in a first housing 9, a partition member 10 and a second housing 11, which will be described later, except for one end, and includes an input shaft 12, a first linking shaft 13 and a second linking shaft 14. ing. One end of the input shaft 12 is linked to the steering wheel, and is used for input of steering torque by the driver. The other end of the input shaft 12 is inserted into an opening recess 13 a formed on one end side of the first linking shaft 13 . The input shaft 12 is rotatably supported by a bearing such as a first ball bearing 15 provided on the inner peripheral surface of the first housing 9 . One end of the first linking shaft 13 is connected to the input shaft 12 via a torsion bar 16 so as to be relatively rotatable. Provide for input. The first linking shaft 13 is supported by a bearing such as a second ball bearing 17 provided on the inner peripheral portion of the partition member 10 and a bearing provided on the inner peripheral surface of the second housing 11 such as a third ball bearing 18. rotatably supported. One end of the second linking shaft 14 is fixed to the outer periphery of the other end of the first linking shaft 13 , while the other end is rotatably supported by a bearing such as a fourth ball bearing 19 .

Here, for convenience of the following description, the direction along the rotation axis P of the steering shaft 1 is defined as "axial direction", and the direction orthogonal to the axial direction is defined as "radial direction". The circumferential direction is defined as "circumferential direction".

The first housing 9 is made of metal, such as an aluminum alloy, and has a cylindrical shape. The first housing 9 is arranged on one end side of the steering shaft 1 and, as shown in FIG. there is As shown in FIG. 2, the first housing 9 includes a small-diameter portion 9a located at one end of the steering shaft 1, and a large-diameter portion 9a integrally formed with the small-diameter portion 9a and having a larger diameter than the small-diameter portion 9a. and a diameter portion 9b. A space inside the small-diameter portion 9a serves as a bearing housing portion 21 for housing the first ball bearing 15 therein. A space inside the large-diameter portion 9b serves as a sensor accommodating portion 22 for accommodating the torque sensor 8. As shown in FIG.

An annular flange portion 9c projecting radially outward from the outer peripheral portion is formed on the outer peripheral portion of the large diameter portion 9b. The annular continuous surface of the flange portion 9c on the other end side is abutted against the distal end surface of the annular first projection portion 10a protruding from the surface of the metal partition member 10 on the one end side. In the combined state, the outer peripheral surface of the peripheral wall of the large diameter portion 9b and the inner peripheral surface of the first protrusion 10a are airtightly sealed by the ring-shaped first seal member 23. As shown in FIG.

The second housing 11 is made of metal such as an aluminum alloy. The second housing 11 includes a cylindrical linking shaft side tubular portion 24 that houses the first linking shaft 13 and the second linking shaft 14, and a cylindrical intermediate shaft that houses the intermediate shaft 2 provided with the ball screw mechanism 4. It is configured by integrally forming the side tubular portion 25 .

The linking shaft-side cylindrical portion 24 includes a cylindrical main body portion 24a, a first enlarged diameter portion 24b that expands from one end of the cylindrical main body portion 24a, and a first enlarged diameter portion 24b that expands from one end of the cylindrical main body portion 24a. and a second enlarged diameter portion 24c formed to have a smaller diameter than the first enlarged diameter portion 24b.
A space inside the first enlarged diameter portion 24 b serves as a first reduction gear accommodating portion 26 that accommodates the first reduction gear 7 . The first reduction gear housing portion 26 is positioned below the sensor housing portion 22 with the partition member 10 interposed therebetween. One end of the peripheral wall of the first enlarged diameter portion 24b is abutted against the surface on the other end side of the partition member 10, and in this abutted state, the outer peripheral surface of the peripheral wall of the first enlarged diameter portion 24b and the partition member 10 A ring-shaped second projection 10 b projecting from the other end side of the second projection 10 b is airtightly sealed by a ring-shaped second sealing member 27 . The second protrusion 10b is positioned radially outward of the first protrusion 10a.

In addition, the partition member 10 has a through hole 10c through which one end of the first linking shaft 13 passes through at its central portion. In the vicinity of the through hole 10c of the surface on the one end side of the partition member 10 (the upper surface in FIG. 2), an annular third protrusion 10d is formed to protrude toward the other end. A second ball bearing 17 that rotatably supports the first linking shaft 13 is provided on the inner peripheral surface of the third protrusion 10d.

A third ball bearing 18, which rotatably supports the first linking shaft 13, is provided on the inner peripheral surface of the first enlarged diameter portion 24b on the other end side.

Bearings for rotatably supporting the second linking shaft 14 are provided on the inner peripheral surface of the second enlarged diameter portion 24c and a part of the inner peripheral surface axially adjacent to the second enlarged diameter portion 24c. For example, a fourth ball bearing 19 is provided.

The side portion of the second enlarged diameter portion 24c and the side portion of the tubular main body portion 24a adjacent to the second enlarged diameter portion 24c in the axial direction are the side portion of the intermediate shaft side tubular portion 25 on the other end side. They are connected via a connecting portion 28 with a predetermined inclination angle α. Here, the inclination angle α is, for example, an angle in the range of 30 to 60 degrees, and is about 35 degrees in this embodiment. It should be noted that the inclination angle α is not necessarily set within the range described above, but is appropriately set according to the design of the vehicle in which the steering device is mounted. The space of the connecting shaft side tubular portion 24 on the other end side of the coupling portion 28 communicates with the space of the intermediate shaft side tubular portion 25 below the coupling portion 28, and the space in communication with the space below the coupling portion 28. A portion serves as a gear mechanism accommodating portion 29 that accommodates the gear mechanism 3 . The gear mechanism accommodating portion 29 is attached to the inclined axial end face 24d of the linking shaft side tubular portion 24 and the inclined axial end face 25a of the intermediate shaft side tubular portion 25 by fastening members (not shown), such as bolts. It is closed by fixing the circular plate-shaped first cover member 30 via a fastening member (not shown) such as a bolt.

The intermediate shaft side cylindrical portion 25 has a substantially constant diameter along the longitudinal direction. The intermediate shaft-side tubular portion 25 is located at one end in the axial direction of the rotation axis Q of the intermediate shaft 2 that is inclined at an inclination angle α with respect to the rotation axis P of the steering shaft 1 (diagonally upper right in FIG. 2). It is closed by a lid member 31 . The second lid member 31 is formed in a cylindrical shape with a bottom, and has a male screw portion formed on its outer peripheral surface. The second lid member 31 is attached and fixed to the intermediate shaft side tubular portion 25 by screwing the male threaded portion into the female threaded portion formed on the inner peripheral surface of the intermediate shaft side tubular portion 25 .

A bearing for rotatably supporting the intermediate shaft 2 , for example, a fifth ball bearing 32 is provided on the inner peripheral surface of the second lid member 31 . The fifth ball bearing 32 is mounted between the second cover member 31 and the intermediate shaft 2 by screwing the second cover member 31 into the intermediate shaft-side cylindrical portion 25 while in contact with the annular protrusion 2 a provided on the intermediate shaft 2 . It is fixed between the shafts 2.

A portion of the inner peripheral surface of the intermediate shaft-side cylindrical portion 25 adjacent to the gear mechanism accommodating portion 29 is a bearing support portion 25b formed in a diameter-reduced shape. A sixth ball bearing 33 is provided to rotatably support the intermediate shaft 2 . The sixth ball bearing 33 is brought into contact with both the annular projection 25c provided on the intermediate shaft side cylindrical portion 25 and the stepped portion 2b provided on the intermediate shaft 2, so that the intermediate shaft side cylindrical portion 25 and the intermediate shaft 2.

A space between the fifth ball bearing 32 and the sixth ball bearing 33 in the internal space of the intermediate shaft side cylindrical portion 25 serves as a ball screw mechanism accommodating portion 34 that accommodates the ball screw mechanism 4 . As shown in FIG. 2, the part of the ball screw mechanism accommodating portion 34 that faces the linking shaft side tubular portion 24 is linked via a generally cylindrical output shaft peripheral wall portion 35 that surrounds the sector gear 5, which is the output shaft. It is connected to the tubular body portion 24 a of the shaft-side tubular portion 24 . The output shaft peripheral wall portion 35 is provided between the first enlarged diameter portion 24b of the linking shaft side cylindrical portion 24 and the coupling portion 28 at a position closer to the first enlarged diameter portion 24b. A space inside the output shaft peripheral wall portion 35 serves as a gear accommodation portion 36 that accommodates the sector gear 5 , and the gear accommodation portion 36 opens to the ball screw mechanism accommodation portion 34 of the intermediate shaft side cylindrical portion 25 . ing. The gear housing portion 36 and a portion of the ball screw mechanism housing portion 34 adjacent to the gear housing portion 36 are, as shown in FIGS. The intermediate shaft side cylindrical portion 25 is closed by attaching a plate-like third lid member 38 by 37 .

The torque sensor 8 includes a permanent magnet (not shown), a holder member 39, a pair of first and second yokes (not shown), a pair of first and second magnetic flux collecting rings 40 and 41, and a magnetic sensor (not shown). and consists mainly of The permanent magnet, holder member 39, first and second yokes, and magnetic flux collection rings 40 and 41 are all arranged substantially concentrically with the rotation axis P of the steering shaft 1. As shown in FIG.

The permanent magnet is a magnetic member that is made of a magnetic material and has a substantially cylindrical shape and is attached and fixed to the outer periphery of the first link shaft 13 on the one end side. The permanent magnet is configured by alternately arranging (magnetizing) N poles and S poles along the circumferential direction of the permanent magnet.

The holder member 39 is formed in a substantially cylindrical shape and is attached and fixed to the outer periphery of the other end of the input shaft 12 .

The pair of first and second yokes are both formed of a soft magnetic material in a substantially cylindrical shape, connected to the input shaft 12 via a holder member 39, and arranged so that the other end faces the permanent magnet in the radial direction. is provided in The first and second yokes are welded and fixed to the holder member 39 by annular welding plates (not shown).

The pair of magnetism collecting rings 40 and 41 are substantially annular rings that collect the magnetic flux of the permanent magnets leaked to one end of both yokes in a predetermined range. The magnetic flux collection ring 40 is arranged on the outer peripheral side of the torque sensor 8 , while the magnetic flux collection ring 41 is arranged on the inner peripheral side of the torque sensor 8 so as to face the magnetic flux collection ring 40 . A magnetism collecting portion 40a having a flat surface (not shown) is provided at a predetermined position in the circumferential direction of the magnetism collecting ring 40. On the other hand, a magnetism collecting portion 40a is provided at a position facing the magnetism collecting portion 40a in the circumferential direction of the magnetism collecting ring 41. is provided with a magnetic flux collecting portion 41a having a flat surface (not shown) parallel to the flat surface of the magnetic flux collecting portion 40a.

The magnetic sensor includes a Hall element (not shown) housed in a radial gap between the flat surface of the magnetic flux collecting portion 40a and the flat surface of the magnetic flux collecting portion 41a, and a substrate (not shown) for connecting the Hall element. and connection terminals (not shown). The magnetic sensor uses the Hall effect of the Hall element to detect the magnetic flux passing between the opposing flat surfaces of the

magnetic flux collectors

40a and 41a, and outputs a signal corresponding to this magnetic flux to a substrate (not shown). output to As a result, calculation of the relative rotation angle between the input shaft 12 and the first linking shaft 13 on the substrate and calculation of the steering torque based on the relative rotation angle are performed.

The gear mechanism 3 includes a first bevel gear 42 fixed to the outer peripheral portion on the other end side of the second linking shaft 14 and a second gear mechanism 42 fixed to the outer peripheral portion on the other end side of the intermediate shaft 2 and meshing with the first bevel gear 42 . and a bevel gear 43. The first bevel gear 42 has a plurality of first teeth 42a inclined toward the other end in the direction of the rotation axis P of the steering shaft 1. It has a plurality of second tooth portions 43a inclined toward the other end in the direction of . The number of the first tooth portions 42a and the number of the second tooth portions 43a are set to be the same, so the speed ratio between the first bevel gear 42 and the second bevel gear 43 is 1:1. Since the first tooth portion 42a and the second tooth portion 43a are connected to each other by meshing, the rotation axis Q of the intermediate shaft 2 is inclined at an angle α with respect to the rotation axis P of the steering shaft 1 extending in the vertical direction. It's like

The ball screw mechanism 4 includes an intermediate shaft side ball screw groove 2c that is a spiral groove provided on the outer peripheral side of the intermediate shaft 2, and a nut side ball screw groove 44a that is a spiral groove provided on the inner peripheral side of the nut 44. , and a plurality of balls 45 arranged between the

ball screw grooves

2c and 44a. The ball 45 supports the nut 44 rotatably relative to the intermediate shaft 2 . The outer peripheral surface of the nut 44 is slidably in contact with the inner peripheral surface of the ball screw mechanism accommodating portion 34 . This allows the nut 44 to slide along the rotation axis Q of the intermediate shaft 2 inside the ball screw mechanism accommodating portion 34 .

In addition, a plurality of rack teeth 44b are formed on the outer peripheral portion of the nut 44 on the sector gear 5 side. These rack teeth 44b are meshed with the tooth portion 5a of the sector gear 5. As shown in FIG.

The sector gear 5 is provided swingably within the gear housing portion 36 . One axial end of the sector gear 5 is connected to a nut 44 via a toothed portion 5a, and the other end is linked to a steering wheel (not shown) via a pitman arm 46 and a drag link and ball joint (not shown). there is

The pitman arm 46 is attached to the other end side of the sector gear 5 so as to be rotatable around the rotation axis R of the sector gear 5 . The pitman arm 46 is rotatable clockwise from the position indicated by the solid line in FIG. 2 to a position of 90 degrees (the position of the left pitman arm 46 indicated by the two-dot chain line). Also, when the pitman arm 46 rotates, the trajectory of the pitman arm 46 and the trajectory of the drag ring (not shown) connected to the pitman arm 46 do not interfere with parts or components positioned below the steering device. It's like

The first speed reducer 7 is arranged in a first speed reducer accommodating portion 26 provided in the large diameter portion 9b of the cylindrical portion 24 on the linking shaft side. The first speed reducer 7 reduces the speed of rotation from the first electric motor 6 and is composed of a worm gear formed by meshing a worm shaft (not shown) and a worm wheel 47 .

The worm wheel 47 has a generally cylindrical metal core portion 47a and a synthetic resin gear forming portion 47b provided on the outer peripheral portion of the core metal portion 47a. The gear forming portion 47b meshes with a worm formed on a worm shaft.

The first electric motor 6 is connected to the first linking shaft 13 via the first speed reducer 7, and is a three-phase AC motor that applies assist torque to the first linking shaft 13 in accordance with the twist amount of the torsion bar 16. is configured as a brushless motor. As shown in FIG. 1 , the first electric motor 6 is integrated with a first EPS controller 48 that controls the first electric motor 6 based on the steering torque from the torque sensor 8 . The first electric motor 6 is housed in a motor housing 49 , and the motor housing 49 is attached and fixed to a worm shaft housing 50 integrally formed with the first housing 9 . The first electric motor 6 has a motor shaft (not shown), and one axial end of the motor shaft is connected to a worm shaft (not shown). The first electric motor 6 and the first EPS controller 48 are provided at a position higher than the sector gear 5 and lower than the driving floor (not shown).

In such a steering device, when the driver rotates the steering wheel, the input shaft 12 rotates and the torsion bar is twisted. do. The rotational forces of the first and

second linking shafts

13 and 14 are transmitted to the intermediate shaft 2 through the engagement of the first bevel gear 42 and the second bevel gear 43 . As the intermediate shaft 2 rotates, the nut 44 moves in the direction of the rotation axis Q of the intermediate shaft 2 , thereby rotating the sector gear 5 . As a result, the pitman arm 46 is pulled in the width direction of the vehicle body, thereby changing the direction of the steered wheels.

In the first embodiment, an example of manual driving in which the steering force from the driver is input to the steering shaft 1 is disclosed. The present invention can be applied to

[Effects of the first embodiment]
As described above, in the first embodiment, the sector gear 5 is arranged radially outside the steering shaft 1, and the steering shaft 1 and the intermediate shaft 2 are connected to each other via the first and second bevel gears 42, 43. By being connected, the intermediate shaft 2 is arranged on the opposite side of the steering shaft 1 with the sector gear 5 interposed therebetween. More specifically, the intermediate shaft 2 is tilted at the tilt angle α with respect to the steering shaft 1 by the first and second bevel gears 42 and 43 . In such a configuration of the steering shaft 1 and the intermediate shaft 2, the torque sensor 8 and the first electric motor 6 are provided on the steering shaft 1, while the ball screw mechanism 4 is provided on the intermediate shaft 2. .

Therefore, since the axial length of the ball screw mechanism 4 including the stroke of the nut 44 is not added to the steering shaft 1, the torque sensor, the first electric motor and the ball screw mechanism are all provided on the steering shaft. With respect to the configuration, the axial dimensions of the steering device can be reduced. Such a steering system is particularly effective for small trucks.

In the conventional steering device, a torque sensor, a ball screw mechanism, and a first electric motor (a first reduction gear connected to the first electric motor) are arranged in order from one end of the steering shaft. There is no space for providing the first reduction gear between one end of the steering shaft and the torque sensor. In addition, since it is necessary to secure the deflection angle of the sector gear due to the movement of the nut of the ball screw mechanism, the first reduction gear is provided between the torque sensor and the ball screw mechanism without increasing the axial dimension of the steering device. Unable to secure space for placement. Furthermore, since the design from the sector gear to the steered wheels is also fixed, the steering shaft and the sector gear have a fixed positional relationship. For these reasons, in the prior art, in order to dispose the first electric motor while maintaining the positional relationship between the steering shaft and the sector gear, the first electric motor, more specifically, the first electric motor connected to the first electric motor The speed reducer has to be arranged at the other end (lower side) of the steering shaft.

However, when the first reduction gear is arranged at the other end of the steering shaft, the drag link connected to the pitman arm may interfere with the motor housing when the pitman arm rotates.

Furthermore, the first electric motor provided on the other end side of the steering shaft is easily affected by water and pebbles that enter the lower part of the vehicle from the road surface, causing electrical failure of the first electric motor and damage to the motor housing. was likely to occur.

On the other hand, in the first embodiment, the first electric motor 6 is provided at a position higher than the sector gear 5 . In other words, the first electric motor 6 is provided at a position far away from the pitman arm 46 and the drag link. Therefore, it is possible to prevent the drag link from damaging the motor housing 49 and the first EPS controller 48 when the pitman arm 46 rotates.

Furthermore, when the first electric motor 6 is positioned higher than the sector gear 5, it becomes difficult for water and pebbles from the road surface to reach the first electric motor 6. Electrical failure of the electric motor 6 and damage to the motor housing 49 and the first EPS controller 48 can be suppressed.

Also, when the first electric motor 6 is arranged higher than the sector gear 5 in this way, it is possible to easily achieve the minimum ground clearance standard indicating the vertical distance between the road surface and the lowest part of the vehicle.

Also, in the conventional steering device, the ball screw mechanism is provided on the steering shaft, and the teeth of the sector gear mesh with the rack teeth of the nut of the ball screw mechanism. As described above, the steering shaft and the sector gear have a certain positional relationship, so it is possible to increase the outer diameter of the ball screw mechanism, which requires relatively high rigidity to transmit thrust to the sector gear. The problem was that it was difficult.

On the other hand, in the first embodiment, the intermediate shaft 2 is inclined with respect to the steering shaft 1 at the inclination angle α, and furthermore, the toothed portion 5a of the sector gear 5 is positioned outside the linking shaft side cylindrical portion 24. It meshes with the rack teeth 44b of the nut 44 of the ball screw mechanism 4.

Therefore, the outer diameter of the ball screw mechanism 4 can be increased without being constrained by the positional relationship between the steering shaft 1 and the sector gear 5, and the degree of freedom in designing the ball screw mechanism 4 can be improved. Furthermore, the steering apparatus having the configuration of the first embodiment can be applied not only to small-sized trucks but also to large-sized trucks.

[Second embodiment]
FIG. 4 is a top view of the steering device of the second embodiment. FIG. 5 is a longitudinal cross-sectional view of the steering device of the second embodiment taken along line BB in FIG.

In the second embodiment, the steering shaft 1 is the first shaft and the intermediate shaft 2 is the second shaft. and the first electric motor 6 are provided on the intermediate shaft 2 . In other words, the second embodiment shows an example in which the first electric motor 6 provided on the steering shaft 1 in the first embodiment is provided on the intermediate shaft 2 . Along with this, the first reduction gear accommodating portion 26 of the first embodiment is eliminated, and the axial dimension of the first enlarged diameter portion 24b of the linking shaft side cylindrical portion 24 becomes shorter than in the first embodiment. ing.

The second cover member 31 has a circular shaft through-hole 31a formed in its central portion, and the small-diameter end portion 2d of the intermediate shaft 2 formed in a stepped diameter reduction shape is inserted into the shaft through-hole 31a. is penetrating. A worm wheel 47 that constitutes a part of the first speed reducer 7 is attached and fixed to the outer peripheral portion of the small-diameter end portion 2 d that protrudes outward from the second lid member 31 . The first reduction gear accommodating portion 26 of the second embodiment that accommodates the first reduction gear 7 is closed by attaching a cup-shaped closing member 51 to the outer peripheral portion of the intermediate shaft side cylindrical portion 25 . .

[Effect of Second Embodiment]
In a second embodiment, in a shaft configuration in which the intermediate shaft 2 is inclined with respect to the steering shaft 1 by first and second bevel gears 42, 43, the torque sensor 8 is provided on the steering shaft 1, while the ball screw A mechanism 4 and a first electric motor 6 are provided on the intermediate shaft 2 .

For this reason, since the first speed reducer 7 is not arranged inside the first enlarged diameter portion 24b, by shortening the axial dimension of the first enlarged diameter portion 24b, the axial direction of the steering device can be reduced more than in the first embodiment. Dimensions can be reduced.

Further, in the second embodiment, since the ball screw mechanism 4 and the first electric motor 6 are provided on the intermediate shaft 2, the intermediate shaft side ball screw groove 2c and the nut side ball screw groove 44a of the ball screw mechanism 4 By shortening the lead of the ball screw mechanism 4, the speed of the ball screw mechanism 4 can be reduced, and the assisting force to the intermediate shaft 2 can be increased. Further, if the lead is shortened, the assist force of the first electric motor 6 can be reduced by the amount of the shortened lead, so the first electric motor 6 can be miniaturized. Furthermore, by increasing the speed ratio of the first and second bevel gears 42 and 43 by the shortened lead, the total speed ratio from the input shaft 12 to the sector gear 5 can be kept constant, whereby the ball screw mechanism 4 and the speed ratio of the first and second bevel gears 42 and 43 can be improved.

[Third Embodiment]
FIG. 6 is a top view of the steering device of the third embodiment. 7 is a vertical cross-sectional view of the third embodiment of the steering device taken along line CC of FIG. 6. FIG.

The third embodiment is a combination of the configuration of the steering device of the first embodiment and the configuration of the steering device of the second embodiment. That is, in the third embodiment, the torque sensor 8 and the first electric motor 6 are provided on the steering shaft 1, while the ball screw mechanism 4 and the second electric motor 6 having the same configuration as the first electric motor 6 are provided. A motor 52 is provided on the intermediate shaft 2 .

As shown in FIG. 7, the first electric motor 6 is arranged so that the second EPS controller 53 is located on the rear side of the first housing 9 and the linking shaft side cylindrical portion 24 when viewed from the direction of the rotation axis R of the sector gear 5 (see FIG. 7). back side).
[Effect of the third embodiment]
In the third embodiment, the intermediate shaft 2 is tilted at the tilt angle α with respect to the steering shaft 1 by the first and second bevel gears 42 and 43. , while the ball screw mechanism 4 and the second electric motor 52 are provided on the intermediate shaft 2 .

Therefore, the two motors of the first and second

electric motors

6, 52 can supply larger assist torque than in the first and second embodiments. Further, even if one of the first and second

electric motors

6, 52 fails, the other of the first and second

electric motors

6, 52 can continue to operate the steering device.

[Fourth embodiment]
FIG. 8 is a top view of the steering device of the fourth embodiment. FIG. 9 is a longitudinal sectional view of the fourth embodiment of the steering device taken along line DD in FIG. FIG. 10 is a partial cross-sectional view of the first electric motor 6, etc. taken along line EE in FIG.

As shown in FIG. 9, in the fourth embodiment, the intermediate shaft 2 is connected orthogonally to the steering shaft 1 via the gear mechanism 3. A torque sensor 8 and a ball screw mechanism 4 are provided on the steering shaft 1 , while a first electric motor 6 is provided on the intermediate shaft 2 . Further, in the fourth embodiment, the partition member 10 of the first to third embodiments is eliminated, and the first housing 9 is directly attached to the linking shaft side cylindrical portion 24 by bolts 20. FIG. Further, the linking shaft side tubular portion 24 is formed separately from the intermediate shaft side tubular portion 25 .

In the fourth embodiment, the first housing 9 further has a medium-diameter portion 9d located between the small-diameter portion 9a and the large-diameter portion 9b, and the space inside the medium-diameter portion 9d is used to generate torque. A sensor accommodating portion 22 that accommodates the sensor 8 is formed.

The linking shaft side tubular portion 24 has a generally cylindrical shape, and a portion of the outer peripheral portion bulges radially outward to form an output shaft surrounding wall portion 35 . The output shaft surrounding wall portion 35 opens inside the linking shaft side tubular portion 24 . In the output shaft peripheral wall portion 35 , the sector gear 5 is arranged such that the tooth portion 5 a faces the second linking shaft 14 , and the tooth portion 5 a is a ball screw provided around the second linking shaft 14 . It meshes with the rack teeth 44b of the nut 44 of the mechanism 4.

In addition, a linking shaft side ball screw groove 14 a that constitutes a part of the ball screw mechanism 4 is formed on the outer peripheral surface of the second linking shaft 14 at the central portion in the axial direction.

A substantially annular bearing holding member 55 for holding a bearing, for example, a seventh ball bearing 54 is provided inside one end of the linking shaft side tubular portion 24 . A male threaded portion is formed on the outer peripheral surface of the bearing holding member 55 , and this male threaded portion is screwed into a female threaded portion formed on the inner peripheral surface of one end of the linking shaft side cylindrical portion 24 . , the bearing holding member 55 is attached and fixed to the linking shaft side tubular portion 24 . The bearing holding member 55 has a shaft through hole 55a formed in its central portion, and the steering shaft 1 extends axially through the shaft through hole 55a.

As shown in FIG. 9, a diameter-reduced portion 24e having a diameter-reduced shape is formed at the other end portion of the linking shaft-side cylindrical portion 24, and the inner peripheral surface of the diameter-reduced portion 24e has a second A bearing for rotatably supporting the linking shaft 14, for example, an eighth ball bearing 70 is provided.

The intermediate shaft-side cylindrical portion 25 includes a first cylindrical portion 56 that accommodates a portion of the second linking shaft 14 and a second cylindrical portion 56 that is integrally formed with the first cylindrical portion 56 and accommodates a portion of the intermediate shaft 2 . and a cylindrical portion 57 .

One end of the first cylindrical portion 56 serves as a support portion for installing the linking shaft side cylindrical portion 24 , while the other end is formed to have a smaller diameter than the one end and serves as a portion coupled to the second cylindrical portion 57 . It's becoming An end portion 56a of the first cylindrical portion 56 that is not coupled to the second cylindrical portion 57 is inclined radially outward.

The second cylindrical portion 57 has an annular projecting portion 57a formed on its inner peripheral surface, and the annular projecting portion 57a has a bearing, for example, a ninth ball bearing 58, for rotatably supporting the intermediate shaft 2. is in contact with one end of the outer race 58a. With one end of the outer race 58a in contact with the annular projecting portion 57a, the other end of the outer race 58a is held by a first retaining ring 59 provided on the inner circumference of the second cylindrical portion 57 so as to be attached to the intermediate shaft 2. It is fixed to the second cylindrical portion 57 by pressing it toward one end in the direction. One end of the inner race 58b of the ninth ball bearing 58 is in contact with a stepped portion 2e formed near the center of the intermediate shaft 2 in the axial direction. The inner race 58 b is in contact with the stepped portion 2 e of the intermediate shaft 2 , and the other end of the inner race 58 b is pushed toward one axial end of the intermediate shaft 2 by a second retaining ring 60 provided on the outer periphery of the intermediate shaft 2 . It is fixed to the intermediate shaft 2 by pressing.

A second bevel gear 43 is attached and fixed to the first bevel gear 42 at right angles to the small-diameter end 2 d of the intermediate shaft 2 on the one axial end side. The first toothed portion 42a of the first bevel gear 42 and the second toothed portion 43a of the second bevel gear 43 mesh with each other so that the rotation axis Q of the intermediate shaft 2 is perpendicular to the rotation axis P of the steering shaft 1. .

The inner side of the closing member 51 serves as a first reduction gear accommodating portion 26 in which the first reduction gear 7 that reduces the rotation speed of the first electric motor 6 is accommodated. A part of the outer peripheral portion of the closing member 51 communicates with a worm shaft accommodating portion 61, which will be described later, provided in the worm shaft housing 50 shown in FIG.

The worm shaft housing 50 is formed integrally with a cylindrical shaft tubular portion 50a and is formed in a conical tapered shape that gradually expands in diameter toward the first electric motor 6 side. and a tapered conical portion 50b. A space inside the shaft cylindrical portion 50a and the conical tapered portion 50b serves as a worm shaft housing portion 61 for housing a worm shaft 62 therein. One axial end portion 50c of the conical tapered portion 50b is fixed to the outer peripheral portion of a stepped reduced diameter portion 49a formed in the motor housing 49 in a stepped diameter reduced shape. A ring-shaped fourth seal member 63 airtightly seals the inner peripheral surface of the one axial end portion 50c and the outer peripheral surface of the stepped reduced diameter portion 49a.

The opening at the other end in the axial direction of the cylindrical shaft portion 50a is closed by a breathing valve 64 that allows the air inside the worm shaft housing 50 to escape to the outside.

The worm shaft 62 is made of a metal material and has a substantially cylindrical shape. The worm shaft 62 has one end fixed to the motor shaft 65 and the other end positioned in the worm shaft housing 61 near the breathing valve 64 . The worm shaft 62 has a cylindrical shaft portion 62a and a spiral tooth portion 62b formed on the outer peripheral portion of the shaft portion 62a and continuing in a spiral shape. The helical tooth portion 62b meshes with the gear forming portion 47b of the worm wheel 47 of the first speed reducer 7. As shown in FIG.

As shown in FIG. 10, a bearing for rotatably supporting the worm shaft 62, such as a deep groove ball bearing 66, is provided on the outer peripheral portion of the worm shaft 62 on one end side in the axial direction.

A tenth ball bearing 67, which rotatably supports the worm shaft 62, is provided on the outer peripheral portion of the worm shaft 62 on the other end side in the axial direction. A tenth ball bearing 67 is supported by a bearing support member 68 provided between the worm shaft 62 and the breathing valve 64 . More specifically, the bearing support member 68 has a circular recess 68a formed in a surface facing the other axial end of the worm shaft 62, and the tenth ball bearing 67 is fitted into this circular recess 68a. , the tenth ball bearing 67 is supported by the bearing holding member 68 . The outer peripheral surface of the bearing holding member 68 and the inner peripheral surface of the cylindrical shaft portion 50a are airtightly sealed by a ring-shaped fifth seal member 69. As shown in FIG.

[Effects of the fourth embodiment]
In the fourth embodiment, the torque sensor 8 and the ball screw mechanism 4 are provided on the steering shaft 1 in a shaft configuration in which the intermediate shaft 2 is orthogonal to the steering shaft 1 by the first and second bevel gears 42 and 43. , on the other hand, a first electric motor 6 is provided on the intermediate shaft 2 .

Therefore, since the first electric motor 6 is not arranged on the steering shaft 1, the axial dimension of the steering device can be reduced by the amount of the first electric motor 6 compared to the conventional steering device.

In the first to third embodiments described above, the intermediate shaft 2 is tilted at the tilt angle α with respect to the steering shaft 1 by the first and second bevel gears 42 and 43. The example in which the spur gear is displaced so as to be parallel to the steering axis 1 can be applied to the present invention.

Claims

A steering device that transmits rotational force to steered wheels,
a first axis;
an output shaft positioned radially outward of the first shaft;
a second shaft located on the opposite side of the first shaft across the output shaft;
a gear mechanism connecting the first shaft and the second shaft;
a torque sensor that detects a steering torque associated with the rotational force;
a first electric motor that imparts torque to the rotational force;
a ball screw mechanism that transmits the thrust generated by the rotational force to the output shaft;
with
A steering device, wherein two of the torque sensor, the first electric motor, and the ball screw mechanism are provided on the first shaft, and the remaining one is provided on the second shaft.
The steering device according to claim 1,
the first shaft is a steering shaft connected to a steering wheel;
the second shaft is an intermediate shaft connected to the output shaft;
The torque sensor and the first electric motor are provided on the steering shaft,
The steering device, wherein the ball screw mechanism is provided on the intermediate shaft.
The steering device according to claim 1,
the first shaft is a steering shaft connected to a steering wheel;
the second shaft is an intermediate shaft connected to the output shaft;
The torque sensor is provided on the steering shaft,
A steering device, wherein the first electric motor and the ball screw mechanism are provided on the intermediate shaft.
The steering device according to claim 1,
further comprising a second electric motor that imparts torque to the rotational force;
the first shaft is a steering shaft connected to a steering wheel;
the second shaft is an intermediate shaft connected to the output shaft;
The torque sensor and the first electric motor are provided on the steering shaft,
A steering device, wherein the second electric motor and the ball screw mechanism are provided on the intermediate shaft.
In the steering device according to any one of claims 2 to 4,
The steering device, wherein the gear mechanism includes a first bevel gear fixed to the outer peripheral portion of the steering shaft and a second bevel gear fixed to the outer peripheral portion of the intermediate shaft.
In the steering device according to any one of claims 2 to 4,
The steering device, wherein the first electric motor is provided at a position higher than the output shaft.
A steering device that transmits rotational force to steered wheels,
a first axis;
an output shaft positioned radially outward of the first shaft;
a gear mechanism provided on the first shaft;
a second shaft connected to the first shaft via the gear mechanism;
a torque sensor that detects a steering torque associated with the rotational force;
an electric motor that imparts torque to the rotational force;
a ball screw mechanism that transmits the thrust generated by the rotational force to the output shaft;
with
The torque sensor and the ball screw mechanism are provided on the first shaft,
The steering device, wherein the electric motor is provided on the second shaft.