JP5639460B2 - Tractor steering device - Google Patents

Description

  The present invention relates to a technique of a steering device for a tractor using an electric power steering mechanism that assists a steering force of a front wheel by a driving force of a motor.

  Conventionally, a technique of a steering device for a tractor using an electric power steering mechanism has been publicly known. For example, as described in Patent Document 1.

  According to the steering device for a tractor described in Patent Document 1, the steering force when steering the front wheel by operating the steering wheel can be assisted by the motor (electric actuator). Thus, the operator can operate the handle with a light force. In addition, since the electric actuator does not require engine power, there is no loss in power supply to a working machine such as a tilling device.

  However, when the electric power steering mechanism is used for the steering device of the tractor as described above, it may be difficult to make the steering device compact or the maintainability may be poor.

JP-A-5-8741

  The present invention has been made in view of the circumstances as described above, and provides a tractor steering device that can be configured compactly and can improve maintainability.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

In claim 1, a pair of left and right body frames are arranged with the longitudinal direction as a longitudinal direction, a front axle case pivotally supported by a center pin in the left and right direction of the front lower part of the body frame is provided, and both left and right sides of the front axle case A rack that supports a pair of front wheels and that is arranged in a direction substantially parallel to the longitudinal direction of the fuselage frame and that moves in response to the operation of the handle, and is arranged below the handle for moving the rack In a steering device for a tractor including a rack and pinion type electric power steering mechanism for converting a rotation of the steering wheel into a steering motion of a front wheel, which includes a motor that supplements the force, for steering the front wheels at both ends of the front axle case A bell crank is placed on the inner side of the fuselage than the knuckle arm The rack and one end of the bell crank are connected by a rack link, the other end of the bell crank and the knuckle arm are connected by a connecting rod, and the motor, the rack link, and the bell crank are connected to the front axle. It is arranged below the center pin serving as the pivot point of the case in the vertical direction and above the bottom surface of the front gear case constituting the front axle case .

  According to a second aspect of the present invention, the rack and the bell crank are arranged within a lateral width of the body frame.

  According to a third aspect of the present invention, the motor is configured to be detachable toward the outside of the machine body.

ADVANTAGE OF THE INVENTION According to this invention, the height from the ground can be ensured while the steering device of a tractor is comprised compactly, and the failure, damage, etc. by contact with the ground can be prevented.
In addition, the maintainability of the steering device can be improved.

The side view which showed the whole structure of the tractor. The rear perspective view which showed the steering device. The top view which showed the steering device. The bottom view which showed the steering device. The side view which showed the steering device. The schematic diagram which showed the steering device. (A) Side surface schematic diagram. (B) A schematic plan view. The plane schematic diagram which showed the other structure of the steering device.

  In the following description, the direction of arrow F in the figure is defined as the forward direction, the direction of arrow L as the left direction, and the direction of arrow U as the upward direction.

  First, the overall configuration of the tractor 1 including the steering device 14 will be described with reference to FIG.

  In the tractor 1, a pair of left and right body frames 2, 2 are arranged with the longitudinal direction as the front-rear direction. A front axle case 3 is provided at the front lower part of the body frame 2, 2, and a pair of left and right front wheels 5, 5 are fixed to front axles 4, 4 provided at both left and right ends of the front axle case 3. A mission case 6 is provided at the rear of the body frame 2. 2 and a pair of left and right rear wheels 8 and 8 are fixed to rear axles 7 and 7 provided at both left and right ends of the mission case 6.

  An engine 10 covered with a bonnet 9 is provided at the front part of the body frame 2. 2, and a driving operation unit 13 in which a handle 11, a seat 12, various operation tools and the like are arranged is provided behind the bonnet 9. It is done. In addition, a steering device 14 (see FIG. 2) is provided from the driving operation unit 13 to the front end portions of the body frames 2 and 2.

  Hereinafter, the front axle case 3 will be described with reference to FIGS. 2 to 5. In FIG. 5, for convenience of explanation, the aircraft frame 2 on the left side of the aircraft is not shown.

  The front axle case 3 includes a front gear case 3a, front gear boxes 3b and 3b, a left knuckle arm 3c, a right knuckle arm 3d, a transmission rod 3e, and the like.

  The front gear case 3a is a box-like member that is arranged with its longitudinal direction facing the left-right direction. A center pin 15 is inserted in the front-rear direction at the upper part of the front gear case 3a, and both front and rear ends of the center pin 15 are attached to a pair of front axle brackets 16 and 16 that are horizontally mounted on the left and right body frames 2 and 2. It is rotatably supported. In this manner, the front gear case 3a can swing around the center pin 15.

  Front gear boxes 3b and 3b are provided at both left and right ends of the front gear case 3a. The front gear boxes 3b and 3b are rotatably supported by the front gear case 3a via a king pin (not shown) arranged with the axial direction extending substantially vertically.

  A left knuckle arm 3c is fixed to the upper part of the front gear box 3b on the left side of the machine body, and a right knuckle arm 3d is fixed to the upper part of the front gear box 3b on the right side of the machine body. The front end portion of the left knuckle arm 3c and the front end portion of the right knuckle arm 3d are connected by a transmission rod 3e.

  From the left and right front gearboxes 3b and 3b, the aforementioned front axles 4 and 4 project from the outer sides of the aircraft.

  In the front axle case 3 configured as described above, when the left knuckle arm 3c is rotated, the front gear box 3b on the left side of the machine body is rotated and the front gear box on the right side of the machine body is transmitted via the transmission rod 3e. 3b is rotated. Accordingly, the front wheels 5 and 5 (see FIG. 1) can be steered left and right.

  Hereinafter, the steering device 14 will be described with reference to FIGS. 2 to 6.

  The steering device 14 steers the front wheels 5 and 5 by rotating the left knuckle arm 3 c of the front axle case 3. The steering device 14 includes a handle 11, a handle support shaft 20, a connecting shaft 30, a rack and pinion type electric power steering mechanism 40, a rack link 50, a bell crank 60, a connecting rod 70, and the like.

  First, the outline | summary of the steering apparatus 14 is demonstrated using FIG.

  The upper end of the handle support shaft 20 is fixed to the lower portion of the handle 11. The lower end of the handle support shaft 20 is connected to the upper end of the connection shaft 30 via a universal joint. The lower end of the connecting shaft 30 is connected to the rack and pinion type electric power steering mechanism 40.

  The rack and pinion type electric power steering mechanism 40 converts the rotation of the handle 11 into a motion for steering the front wheels 5 and 5 (specifically, movement of the rack 43 in the front-rear direction, which will be described later). . The rack and pinion type electric power steering mechanism 40 includes a steering shaft 41, a pinion gear 42, a rack 43, an auxiliary gear 44, a motor 45, a torque sensor 46, and the like.

  The upper end of the steering shaft 41 is connected to the lower end of the connecting shaft 30 via a universal joint.

  A pinion gear 42 is formed near the lower end of the steering shaft 41. The pinion gear 42 is meshed with a rack 43 that is disposed with the longitudinal direction thereof substantially in the front-rear direction.

  An auxiliary gear 44 is fixed to the lower end of the steering shaft 41. An output gear 45a of a motor 45 is meshed with the auxiliary gear 44.

  A torque sensor 46 is provided in the middle of the steering shaft 41. The torque sensor 46 can detect the torque applied to the steering shaft 41.

  The torque sensor 46 and the motor 45 are connected to a control device (not shown). The control device can drive the motor 45 based on the torque applied to the steering shaft 41 detected by the torque sensor 46.

  The front end of the rack 43 is connected to the rear end of the rack link 50 through a ball joint.

  The bell crank 60 is disposed at the rear portion of the front gear case 3a, and is supported so as to be rotatable about a rotation shaft 61 that is disposed with the axial line direction substantially vertical. The bell crank 60 has one end portion that protrudes generally leftward from the rotation shaft 61 and the other end portion that protrudes generally forward from the rotation shaft 61 in a plan view (FIG. 6B). It is formed in a substantially L shape.

  One end of the bell crank 60 is connected to the front end of the rack link 50. The other end of the bell crank 60 is connected to one end (right end) of the connecting rod 70. The other end (left end) of the connecting rod 70 is connected to the rear end portion of the left knuckle arm 3c.

  In the steering device 14 configured as described above, when the handle 11 is rotated, the pinion gear 42 is rotated via the handle support shaft 20, the connecting shaft 30, and the steering shaft 41.

  At this time, the control device drives the motor 45 to assist the rotation of the pinion gear 42 according to the torque applied to the steering shaft 41. As a result, the operator can turn the handle 11 with a light force.

  When the pinion gear 42 rotates, the rack 43 engaged with the pinion gear 42 moves in the front-rear direction. The movement of the rack 43 is transmitted to the left knuckle arm 3c via the rack link 50, the bell crank 60, and the connecting rod 70, and the left knuckle arm 3c rotates.

  By rotating the left knuckle arm 3c in this manner, the front wheels 5 and 5 are steered and the tractor 1 can be steered.

  Next, a specific arrangement of the steering device 14 will be described with reference to FIGS.

  Below the handle 11, a steering support block 21 is fixed in the middle in the front-rear direction of the body frames 2 and 2 and between the body frames 2 and 2 (see FIGS. 2, 4 and 5). On the upper part of the steering support block 21, a support pipe 25 is arranged in a generally vertical direction via a frame support bracket 22, a steering frame 23, a steering support bracket 24, and the like. The frame support bracket 22, the steering frame 23, the steering support bracket 24, and the support pipe 25 are covered with a dashboard 17 (see FIG. 1).

  The handle support shaft 20 is rotatably supported by the support pipe 25, and is guided so that the longitudinal direction thereof is generally directed in the vertical direction.

  A steering gear case 47 is fixed to the lower portion of the steering support block 21. The steering gear case 47 is disposed within the left-right width of the body frame 2. In the steering gear case 47, the lower portion of the steering shaft 41, the pinion gear 42, the rack 43, the auxiliary gear 44, the output gear 45a of the motor 45, and the like are housed.

  Since the steering gear case 47 is disposed between the body frames 2 and 2, it can be prevented from hitting an obstacle or the like from the outside in the left-right direction and being damaged. Further, since the steering gear case 47 can be arranged behind the front wheels 5 and 5, it can be configured such that mud or the like is not applied when the steering wheel 11 is largely cut by a muddy or the like and turned. Further, since the steering case 47 is disposed between the left and right body frames 2 and 2 between the front wheels 5 and 5 and the rear wheels 8 and 8 of the body, the weight balance of the tractor 1 can be improved.

  The steering gear case 47 has a cylindrical portion disposed so as to be substantially parallel to the longitudinal direction (front-rear direction) of the body frames 2 and 2, and the rack 43 is accommodated along the longitudinal direction of the cylindrical portion. That is, the rack 43 is arranged in a direction substantially parallel to the longitudinal direction (front-rear direction) of the body frames 2.

  A bellows tube 47 a that can extend and contract in the front-rear direction is provided at the front end of the cylindrical portion of the steering gear case 47. Since the bellows tube 47a expands and contracts with the movement of the rack 43 in the front-rear direction, the rack 43 can be always stored even if the rack 43 moves.

  A motor 45 is detachably fixed to the left side surface of the steering gear case 47 with bolts or the like. The longitudinal direction of the motor 45 (the axial direction of the motor 45) is arranged so as to be substantially in the left-right direction. When the motor 45 is removed from the steering gear case 47, the motor 45 can be extracted to the left side (outside) of the machine body. .

  Between the steering support block 21 and the front axle case 3, and in the vicinity of the front axle case 3, a crank support frame 62 is fixed to the lower part of the body frame 2. The rotation shaft 61 is supported by the crank support frame 62 so as to protrude downward. A bell crank 60 is rotatably supported on the rotation shaft 61. In this manner, the bell crank 60 is disposed within the left and right widths of the body frames 2 and 2 and inside the body of the left knuckle arm 3c.

  In the steering apparatus 14 configured as described above, the motor 45, the rack link 50, the bell crank 60, and the like are below the center pin 15 serving as a swing fulcrum of the front axle case 3 in the vertical direction. 3 (more specifically, it is arranged above the bottom surface of the front gear case 3a) in the up-down direction (see the dashed line in FIG. 5). Accordingly, the height from the ground is secured while the steering device 14 is configured as compact as possible, and failure or damage due to contact with the ground is prevented.

  Further, the motor 45, the rack link 50, the bell crank 60, and the like are disposed behind the front axle case 3 (more specifically, the front gear case 3a). Thus, the front axle case 3 protects the obstacles from the front from coming into contact with the motor 45 and the like.

  As described above, the steering device 14 of the tractor 1 according to the present embodiment is arranged in a direction substantially parallel to the longitudinal direction of the body frames 2 and 2, and the rack 43 that moves according to the operation of the handle 11, and the handle The rack and pinion type electric power steering mechanism 40 which is disposed below the motor 11 and includes a motor 45 which supplements the force for moving the rack 43 and converts the rotation of the handle 11 into the steering motion of the front wheels 5 and 5; The bell crank 60 is disposed inside the body of a left knuckle arm 3c (knuckle arm) for steering 5 and has one end connected to the rack 43, and the other end of the bell crank 60 and the left knuckle arm 3c are connected to each other. And a connecting rod 70. With this configuration, a compact steering device 14 can be configured with a simple mechanism. Further, by orienting the rack 43 in the longitudinal direction of the machine body frames 2 and 2, a space for the stroke of the rack 43 can be secured even when applied to a small tractor. Furthermore, by arranging the motor 45 below the handle 11, that is, below the step of the driving operation unit 13, the front wheels 5 and 5 and the rear wheels 8 and 8 do not get in the way, and maintenance from the side of the machine body is easy. Can be done.

  Further, the rack 43 and the bell crank 60 are arranged within the left and right widths of the body frame 2. With this configuration, a compact steering device 14 can be configured.

  The motor 45 is configured to be detachable toward the left side (outside) of the machine body. With this configuration, the maintenance of the motor 45 from the side of the machine body can be easily performed. In particular, since the tractor 1 is normally loaded and unloaded from the left side of the machine body, maintenance can be further improved if the motor 45 is detachable from the left side of the machine body as in this embodiment.

  The motor 45 can be detachably fixed to the right side surface of the steering gear case 47 so that the motor 45 can be extracted to the right side of the machine body. In the present embodiment, the rack link 50 is connected to the left knuckle arm 3c via the bell crank 60 and the connecting rod. However, the present invention is not limited to this, and the right knuckle arm 3d The structure which connects may be sufficient.

  The tractor steering device can also be configured as follows.

  In the steering device 114 shown in FIG. 7, a rack 143 is provided across the substantially right and left central rear part of the front axle case 3 (more specifically, the front gear case 3a) and the rear end part of the left knuckle arm 3c. A pinion gear 142 is engaged with the rack 143, and the pinion gear 142 is connected to the handle 11.

  Further, below the pinion gear 142, the auxiliary gear 144 is coupled to the pinion gear 142. The auxiliary gear 144 meshes with the output gear 145a of the motor 145.

  The above-described pinion gear 142, rack 143, auxiliary gear 144, motor 145 and the like are appropriately supported by the front axle case 3. That is, when the front axle case 3 swings, the motor 145 and the like swings accordingly.

  Torque applied to a steering shaft (not shown) connecting the handle 11 and the pinion gear 142 is detected by a torque sensor (not shown). The motor 145 and the torque sensor are connected to a control device (not shown). The control device can drive the motor 145 based on the torque detected by the torque sensor. As a result, the operator can turn the handle 11 with a light force.

1 Tractor 2 Airframe Frame 3 Front Axle Case 3c Left Knuckle Arm (Knuckle Arm)
5 Front wheel 11 Handle 14 Steering device 20 Handle support shaft 30 Connection shaft 40 Rack and pinion type electric power steering mechanism 43 Rack 45 Motor 50 Rack link 60 Bell crank 70 Connection rod

Claims (3)

A pair of left and right fuselage frames are arranged with the longitudinal direction as the longitudinal direction, a front axle case pivotally supported by a center pin in the left and right direction of the front lower part of the fuselage frame, and a pair of front wheels supported on the left and right sides of the front axle case And a rack that is arranged in a direction substantially parallel to the longitudinal direction of the fuselage frame and moves in accordance with the operation of the handle, and a motor that is arranged below the handle and supplements the force for moving the rack. In a steering device for a tractor including a rack and pinion type electric power steering mechanism for converting the rotation of the handle into a steering motion of a front wheel,
A bell crank is disposed on the inner side of the body than the knuckle arm provided to steer the front wheel at both ends of the front axle case,
One end of the rack and the bell crank is connected by a rack link,
The other end of the bell crank and the knuckle arm are connected by a connecting rod,
The motor, the rack link, and the bell crank are
Steering of a tractor, wherein the steering wheel is disposed below a center pin serving as a swing fulcrum of the front axle case in a vertical direction and above a bottom surface of a front gear case constituting the front axle case. apparatus.   The tractor steering apparatus according to claim 1, wherein the rack and the bell crank are disposed within a lateral width of the body frame.   3. The tractor steering apparatus according to claim 1, wherein the motor is configured to be detachable toward the outside of the body.

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