Steering apparatus for vehicle

Abstract

To provide a steering device of a vehicle capable of regulating the steering of a wheel while suppressing a load to each mechanism connecting a steering shaft to the wheel at low cost, and easily adjusting the maximum steering angle.SOLUTION: A steering device for a vehicle includes a steering shaft configured to transmit a rotational operation to a steering wheel, a steering gear box including an input shaft coupled to the steering shaft and an output shaft configured to convert the rotational operation of the steering wheel input from the input shaft into a rotational operation for steering wheels, a pitman arm coupled to the output shaft of the steering shaft and configured to swing in accordance with rotation of the output shaft, and a restriction part configured to come into contact with a part of the pitman arm to restrict swinging of the pitman arm, the restriction part being configured to adjust a position where the swinging is restricted.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a steering device for a vehicle. [Background technology]

[0002] Power steering is widely known as a vehicle steering device for assisting a driver's steering operation. Power steering amplifies the rotational force of the steering wheel using a hydraulic pump, an electric motor, or the like. Furthermore, the maximum steering angle (hereinafter referred to as the maximum steering angle) that is the turning angle of the vehicle's wheels as a result of the driver's steering operation is predetermined, and it is necessary to restrict the maximum steering angle so that it does not exceed this predetermined angle.

[0003] For example, Patent Document 1 discloses a vehicle in which a knuckle stopper bolt is provided on the inner surface of a knuckle that supports a wheel and changes the steering angle of the wheel, and the steering angle is regulated by the knuckle stopper bolt abutting against a stopper provided on the axle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 5-92055 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the steering angle is restricted by a knuckle stopper bolt as in Patent Document 1, the rotational force amplified by the power steering places a load on each mechanism connecting the pitman arm to the wheels, such as the steering linkage.

[0006] In the technology of Patent Document 1, a pressure sensor is provided in the stopper, and when the contact pressure detected by the pressure sensor increases, the power steering boost function is reduced, but this configuration requires the provision of a pressure sensor and power steering control, which poses problems such as increased cost and complicated control.In addition, adjusting the left and right maximum steering angles requires adjusting the protruding length of each knuckle stopper bolt, which is time-consuming.

[0007] Therefore, an object of the present disclosure is to provide a vehicle steering device that is low-cost, can regulate the steering of the wheels while reducing the load on each mechanism connecting the steering shaft to the wheels, and can easily adjust the maximum steering angle. [Means for solving the problem]

[0008] The present disclosure has been made to solve at least some of the above-mentioned problems, and can be realized in the following aspects or application examples.

[0009] The steering device of the vehicle according to this application example is characterized by comprising: a steering shaft that transmits rotational motion relative to the steering wheel; a steering gearbox having an input shaft connected to the steering shaft and an output shaft that converts the rotational motion of the steering wheel input from the input shaft into rotational motion for steer- ing wheels; a pitman arm that is connected to the output shaft of the steering shaft and swings in response to rotation of the output shaft; and a regulating unit that comes into contact with a part of the pitman arm to regulate the swing of the pitman arm, the regulating unit being adjustable in position for regulating the swing.

[0010] In this way, the steering of the front wheels is restricted by restricting the swing of the pitman arm, which swings in response to the rotation of the steering wheel. In other words, restricting the steering angle immediately after the power steering is increased prevents unnecessary load from being placed on the mechanisms connecting the pitman arm to the wheels. Furthermore, because the restricting unit is located on the output shaft of the steering gearbox, it is easy to adjust the maximum steering angles to the left and right. This allows for the restriction of wheel steering while reducing the load on the mechanisms connecting the steering shaft to the wheels, without the need for sensors or other devices, and at low cost, and also makes it easy to adjust the maximum steering angle. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an overall side view of a vehicle equipped with a steering device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic side view showing the mechanisms connecting the steering shaft to the wheels in the embodiment. [Figure 3] FIG. 3 is an enlarged view of a main part of the steering gear box of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited to the contents described below, and can be implemented with any modifications within the scope of the gist thereof. Furthermore, the drawings used to describe the embodiments are all schematic representations of components, and may be partially emphasized, enlarged, reduced, or omitted to facilitate understanding, and may not accurately represent the scale, shape, etc. of the components.

[0013] Fig. 1 is an overall side view of a vehicle 1 equipped with a steering device 2 according to this embodiment. Fig. 2 is a side view showing the mechanisms connecting the steering shaft to the wheels. Note that, hereinafter, "height direction" refers to the up-down direction of the vehicle, "vehicle width direction" refers to the left-right direction of the vehicle, and "front-rear direction" refers to the vehicle length direction.

[0014] The vehicle 1 according to this embodiment is a cab-over type vehicle in which the driver's seat is provided in front of the front wheels (wheels), and is, for example, a cargo vehicle such as a truck. The vehicle 1 includes a chassis frame 10, a cab 20, a cargo box 30, and a plurality of wheels 40.

[0015] The chassis frame 10 is a pair of left and right frames extending in the longitudinal direction of the vehicle 1 (only the frame on the right side of the vehicle is shown). As shown in Figure 1, a cab 20 is provided in front of the chassis frame 10, and a cargo box 30 is provided behind the cab 20. In addition, the chassis frame 10 is provided with drive devices such as an engine and a transmission, and various heavy objects.

[0016] A driver's seat 21 is provided in the cab 20. A steering wheel 22 for the driver to operate the steering wheel is provided in front of the driver's seat 21, and a steering shaft 23 extends from the steering wheel 22 to under the floor of the driver's seat 21. The steering wheel 22 and the steering shaft 23 will be described in the steering device 2 described below.

[0017] The vehicle 1 of this embodiment has four wheels 40: left and right front wheels 40a and left and right rear wheels 40b, and the left and right front wheels 40a are steered wheels that change the direction of travel of the vehicle 1. The wheels 40 are suspended from the chassis frame 10 via axles and support the weight of the vehicle 1.

[0018] Next, we will explain the steering device 2 of the vehicle 1. As shown in Fig. 2, the steering device 2 includes a steering wheel 22, a steering shaft 23, a steering column 23a, a steering gear box 24, a pitman arm 25, a drag link 26, a knuckle arm 27, and a tie rod 28.

[0019] The steering wheel 22 has a hub 22b connected to the inside of a substantially circular rim 22a via spokes, and a steering shaft 23 is connected to the hub 22b.

[0020] The steering shaft 23 connects the steering wheel 22 and the steering gear box 24, and rotates around its axis in accordance with the rotation of the steering wheel 22, thereby transmitting the rotational movement of the steering wheel 22 to the steering gear box 24.

[0021] The steering column 23a surrounds the steering shaft 23 and supports the steering shaft 23. Although not shown, the steering column 23a is also provided with functional levers (switches) for blinkers, wipers, etc.

[0022] The steering gearbox 24 is attached to the chassis frame 10 of the vehicle 1. Specifically, as shown in FIG. 2 , the steering gearbox 24 is attached to the outer side of the chassis frame 10 on the right side of the vehicle in the vehicle width direction using connectors such as bolts and nuts. The steering gearbox 24 has a function of converting the rotational movement of the steering wheel 22 into an operation for steering the front wheels 40a. Although not shown, various gears are built into the steering gearbox 24, and a hydraulic mechanism that hydraulically amplifies and outputs rotational torque is also provided. In other words, the steering gearbox 24 has a power steering function that assists steering operation. Note that, in the case where the vehicle 1 is a truck as in this embodiment, a relatively large rotational torque is required to steer the vehicle 1, so hydraulic power steering is preferable, but electric power steering using an electric motor may also be adopted. Furthermore, the power steering does not need to be provided in the steering gearbox and may be provided in another location.

[0023] The steering gear box 24 has an input shaft 241 and an output shaft 242. The input shaft 241 is connected to the steering shaft 23, and a rotational movement due to a steering operation is input via the steering shaft 23.

[0024] The output shaft 242 has a rotation axis in the vehicle width direction and protrudes from the steering gear box 24. The output shaft 242 rotates to steer the front wheels 40a, and outputs a rotation torque that is amplified compared to the rotation torque input to the input shaft 241.

[0025] One end of the pitman arm 25 is connected to the output shaft 242, and the other end is connected to the drag link 26. The pitman arm 25 pivots in the front-to-rear direction with the output shaft 242 as a fulcrum, as the output shaft 242 rotates.

[0026] The drag link 26 extends in the front-to-rear direction toward the right front wheel 40a, and one end of the drag link 26 is connected to the pitman arm 25, and the other end is connected to the knuckle arm 27. The drag link 26 moves in the front-to-rear direction of the vehicle 1 due to the swinging motion of the pitman arm 25.

[0027] The drag link 26 is connected to one end of the knuckle arm 27, and a knuckle (not shown) for the right front wheel 40a is connected to the other end of the knuckle arm 27. The knuckle supports the right front wheel 40a and changes the steering angle of the right front wheel 40a.

[0028] The tie rod 28 extends in the vehicle width direction of the vehicle 1, with one end connected to the right knuckle arm 27 and the other end connected to a left knuckle arm (not shown). The tie rod 28 has the function of moving the left knuckle arm in conjunction with the movement of the right knuckle arm 27.

[0029] In the steering device 2 configured in this manner, the rotational movement of the steering wheel 22 is converted into a swinging movement of the pitman arm 25 via the steering gearbox 24, which operates the right knuckle arm 27 via the drag link 26 to change the steering angle of the right front wheel 40a, and further operates the left knuckle arm via the tie rod 28 to change the steering angle of the left front wheel 40a.

[0030] FIG. 3 is an enlarged view of the main part showing the periphery of the output shaft 242 of the steering gear box 24 in FIG.

[0031] 3, the steering gear box 24 is formed with a base 50. The base 50 is a plate-like member extending in the front-rear direction from the inner side of the case of the steering gear box 24 in the vehicle width direction, and is attached to the chassis frame 10 with bolts and nuts (not shown). The base 50 is formed with bolt support portions 50a, 50b at the front and rear, with the pitman arm 25 sandwiched therebetween.

[0032] Each bolt support portion 50a, 50b protrudes from the base portion 50 toward the outside in the vehicle width direction of the vehicle 1, and extends at least further outward in the vehicle width direction than the installation position of the pitman arm 25. A threaded portion is formed through the bolt support portions 50a, 50b to support a restricting portion 51, which will be described later. The threaded portion is drilled at an angle that matches the inclination of the pitman arm 25 when it swings.

[0033] The restricting portion 51 is composed of a pair of stopper bolts 511a, 511b and lock nuts 512a, 512b. The stopper bolts 511a, 511b are screwed into threaded portions of bolt supports 50a, 50b provided on the base 50. As shown in FIG. 3, each of the stopper bolts 511a, 511b is attached with its tip end protruding toward the pitman arm 25. Each of the stopper bolts 511a, 511b is positioned so that its tip end contacts a portion of the pitman arm 25, thereby restricting the pivoting movement of the pitman arm 25. The restricting portion 51 can adjust the position at which the pivoting movement of the pitman arm 25 is restricted by changing the amount of protrusion of the stopper bolts 511a, 511b from the bolt supports 50a, 50b.

[0034] In the output shaft 242 portion of the steering gear box 24 configured in this manner, the rotational movement transmitted from the steering shaft 23 via the steering gear box 24 is converted into a swinging movement of the pitman arm 25, and this swinging movement is regulated by the regulating portion 51.

[0035] Next, the restriction of the swinging movement of the pitman arm 25 of the steering device 2 according to this embodiment will be described with reference to Fig. 3. The pitman arm 25 shown by the solid line in Fig. 3 is positioned along the height direction, indicating a state in which the steering wheel 22 is not being rotated by the driver, i.e., a state in which the vehicle 1 (front wheels 40a) is moving straight ahead.

[0036] 3 show states in which pitman arms 25A and 25B swing forward and backward in response to the rotation of steering wheel 22. Specifically, pitman arm 25A swinging toward the front of the vehicle represents the case in which steering wheel 22 is rotated to the right (clockwise as seen by the driver). Pitman arm 25B swinging toward the rear of the vehicle represents the case in which steering wheel 22 is rotated to the left (counterclockwise as seen by the driver).

[0037] In each state, pitman arms 25A, 25B come into contact with restricting portion 51 at a position where they have swung by approximately 40 degrees from vertical reference line S, and further swinging is restricted. By restricting the swinging of pitman arms 25A, 25B in this manner, steering wheel 22 cannot rotate any further, and front wheels 40a of vehicle 1 are turned to the maximum steering angle.

[0038] To adjust the maximum steering angle, if the amount by which the stopper bolts 511a, 511b protrude from the bolt support portions 50a, 50b is increased, the stopper bolts 511a, 511b will come into contact with the pitman arm 25 earlier, thereby decreasing the maximum steering angle. Conversely, if the amount by which the stopper bolts 511a, 511b protrude from the bolt support portions 50a, 50b is decreased, the maximum steering angle will increase.

[0039] As described above, the steering device 2 according to this embodiment restricts the steering of the front wheels 40a by restricting the swing of the pitman arm 25, which swings in response to the rotation of the steering wheel 22. In other words, the steering device 2 according to this embodiment restricts the steering angle immediately after the power steering is increased, so the load on the restricting unit 51 is small, and it is possible to prevent unnecessary load from being applied to the mechanisms connecting the steering shaft 23 to the front wheels 40a (the steering gear box 24, the pitman arm 25, the drag link 26, the knuckle arm 27, and the tie rod 28). Furthermore, because the restricting unit 51 is provided on the output shaft 241 of the steering gear box 24, it is easy to adjust the maximum steering angles to the left and right. This allows the steering of the front wheels 40a to be restricted at low cost without the need for sensors or the like, while reducing the load on the mechanisms connecting the steering shaft 23 to the front wheels 40a, and also makes it easy to adjust the maximum steering angle.

[0040] This concludes the description of the embodiment of the present invention, but the aspects of the present invention are not limited to this embodiment.

[0041] Although the above embodiments are directed to freight vehicles such as trucks, the present invention may also be applied to electric vehicles, vehicles equipped with internal combustion engines, hybrid electric vehicles, and the like. [Explanation of symbols]

[0042] 1 vehicle 2. Steering device 10 Chassis frame 20 Cab 21 Driver's seat 22 Steering wheel 23 Steering shaft 23a Steering column 24 Steering gearbox 241 Input shaft 242 output shaft 25 Pitman arm 26 Drag Link 27 Knuckle Arm 28 tie rod 30 packing boxes 40 wheels 40a front wheel 40b rear wheel 50 Base 50a, 50b Bolt support 51 Regulatory Department 511a, 511b Stopper bolts 512a, 512b lock nuts

Claims

[Claim 1] a steering shaft that transmits rotational motion to the steering wheel; a steering gearbox having an input shaft connected to the steering shaft and an output shaft that converts the rotational motion of the steering wheel input from the input shaft into a rotational motion for steering wheels; a pitman arm connected to an output shaft of the steering shaft and swinging in response to rotation of the output shaft; a restricting portion that comes into contact with a portion of the pitman arm to restrict the swing of the pitman arm, and the position at which the swing is restricted is adjustable; A steering device for a vehicle comprising:

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