JPH0651062U - Power steering mechanism of tractor - Google Patents

Abstract

(57) [Summary] [Purpose] In the power steering mechanism of a tractor, conventionally, the arrangement position of the hydraulic valve is limited, and when the stroke of the hydraulic cylinder is reduced,
The turning response to the turning angle of the handle is too sensitive, the operability is poor, and the hydraulic cylinder has a structure in which the piston rod expands and contracts in one of the cylinders.
There was a difference between the left and right turning speeds. Further, the switching mechanism of the front wheel speed increasing device is constituted by a member different from the power steering mechanism. The present invention aims to solve the above-mentioned problems. [Structure] A bevel gear box 9 is arranged between a steering shaft 8 and a hydraulic valve 11, and a hydraulic cylinder is arranged along a side frame 1 so that a cylinder 12 slides on a rod 13 on both sides. The tie rod 19 is rotated from the hydraulic cylinder via a link mechanism, and the gear box 20 of the front wheel speed increasing device is operated.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a power steering mechanism for a tractor.

[0002]

[Prior art]

 Conventionally, in the power steering mechanism of a tractor, a hydraulic valve is directly connected to the steering shaft extending from the steering wheel, and the hydraulic cylinder uses a pressure oil because it is necessary to reduce the stroke to make it compact. Was used to reduce the flow rate of In addition, the hydraulic cylinder has conventionally been a method of fixing the cylinder part and expanding and contracting the piston rod.Because the piston rod was directly connected to the center bell crank and the bell crank with front wheels, the left and right sides of the aircraft It was arranged in the direction.

[0003]

[Problems to be solved by the device]

 In the conventional power steering mechanism, first, since the hydraulic valve is directly connected to the steering shaft, it is necessary to set the hydraulic valve position below the steering wheel when the tractor is small and the installation space is small. At this position, the lower part of the fuselage is the step part where the operator operates, and the ground clearance is low. Therefore, the height above the hydraulic valve installation position is also low, and there is a high risk of hitting an obstacle on the field. Also, when the stroke of the hydraulic cylinder is reduced, even if the flow rate of pressure oil to the hydraulic cylinder is small, it swirls greatly.Therefore, the structure in which the steering shaft is directly connected to the hydraulic valve that sends the pressure oil to the hydraulic cylinder is very small. It makes a large turn even at the turning angle of the handle. That is, the responsiveness of the turning of the airframe to the steering wheel is too sensitive, which makes the steering operation rather difficult. In addition, since the pressure oil flows rapidly, the temperature rise of the oil is high and there is a problem in the durability of the hydraulic system.

Further, in the structure in which the cylinder portion of the hydraulic cylinder is fixed and the rod is expanded and contracted, the expansion and contraction direction of the rod is only one direction, and there is a difference in the operating speed during extension and contraction. There is a problem that the turning speed is different between left and right. Furthermore, since the hydraulic cylinders are also arranged in the left-right direction, if the installation space is limited, it must be considered not to contact the hydraulic cylinders. There is a problem that becomes complicated.

Further, the front wheel speed increasing device for increasing the speed of the front wheels when the vehicle is turning cannot be operated by the parts of the conventional power steering mechanism, and a mechanical member is continuously provided from the steering shaft to rotate the gear in the gear box. Or, since the electromagnetic clutch was operated to operate the switching lever of the front wheel speed increasing device, parts had to be arranged in addition to the power steering mechanism, resulting in high cost. In addition, when the mechanical member is used, there is a high possibility that a difference in turning speed will occur.

[0006]

[Means for Solving the Problems]

 The present invention has the following configuration in order to solve the above problems. That is, in a power steering mechanism of a tractor, a bevel gear box is arranged in the middle of a steering shaft connected to a hydraulic valve from a handle, and a hydraulic cylinder that operates for operating the hydraulic valve is arranged along a side frame. By the operation of the hydraulic cylinder, the gears in the gearbox of the front wheel speed increasing device and the center bell crank that connects the tie rods of the front wheels on both sides are interlocked via a link, and the hydraulic cylinder for rotating the front wheels is also configured. Is a double rod type, one end of the piston rod is fixed to the machine body, and the cylinder slides.

[0007]

[Action]

 Even if a hydraulic cylinder with a small stroke is used, the bevel gear box installed between the steering shaft and the hydraulic valve can be used to adjust the gear ratio in the bevel gear to allow the aircraft to turn at a favorable steering wheel operating angle. You can The arrangement of the bevel gear box increases the degree of freedom in the arrangement position of the hydraulic box. The hydraulic cylinder has a structure in which the cylinder slides on both sides of the rod, so that the left and right turning speeds are equal. Further, since it is arranged along the side frame, it does not interfere with other members during operation. The front wheel speed-increasing device can be switched by the steering mechanism, and the number of members can be reduced.

[0008]

【Example】

 The problems and configurations to be solved by the present invention are as described above. Next, the embodiments of the present invention shown in the accompanying drawings will be described. 1 is a side view of the entire tractor, FIG. 2 is a plan view showing the structure of a steering mechanism in the front part of the machine body from the handle portion, FIG. 3 is a side view thereof, and FIG. 4 is a plan view showing the structure of the steering mechanism in the front part of the machine body. 5 is a plan view showing the configuration of the front wheel speed increasing device in the front part of the machine body, FIG. 6 is a side view showing the configuration of a hydraulic cylinder for power steering, and FIG. 7 is a steering mechanism and a switch of the front wheel speed increasing device having another configuration. FIG. 8 is a plan view showing the mechanism, FIG. 8 is an assembled perspective view showing the structure of the operation box, FIG. 9 is a rear perspective view showing the structure of the float mounted on the rear part of the working machine, and FIG. 10 is a rear perspective view showing another structure. It is a figure.

The overall configuration of the tractor will be described with reference to FIGS. 1 and 2. The tractor is provided with side frames 1.1 on both sides and a front frame 2 on the front part, and an engine E is mounted on the front part between the side frames 1.1 at the front part and in front of the engine E. A battery B is provided and covered with the bonnet 3. A front wheel FW is suspended below, and an operation unit is provided behind the bonnet 3. A driver's seat 5 is arranged above the step 4, and a steering wheel H is provided in front of the driver's seat 5 and a driver's seat 5 is located on the side. The operation box 6 is provided. The transmission case is located below the driver's seat 5, and the rear wheels RW are installed on both sides of the transmission case. The work machine mounting link 7 and the transmission shaft are provided behind the rear case RW, and the rear end The work machine R is attached to.

Next, the power steering mechanism will be described with reference to FIGS. 2 to 4 and 6. As shown in FIG. 3, a bevel gear box 9 is arranged in the vicinity of one side frame 1 from a steering wheel H via a steering wheel H, and a transmission shaft 10 is fixed to a lower part of the side frame 1 from the bevel gear box 9. The hydraulic valve 11 is fitted into the provided hydraulic valve 11 to switch the hydraulic valve 11. On the other hand, the front end of the cylinder rod 13 of the hydraulic cylinder 12 is pivotally supported below the side frame 1 on the same side as the hydraulic valve 11 via the fixing pin 14 on the front frame 2. As a double rod type, a piston 13a is fixedly provided at the center of a cylinder rod 13, and pressure oil is sent from the hydraulic valve 11 to each chamber in the hydraulic cylinder 12 which is partitioned by the piston 13a. It At the upper part of the hydraulic cylinder 12, intake and exhaust ports 12a and 12b for piping are provided at the front and rear with the piston 13a interposed therebetween. Thus, by operating the hydraulic valve 13 hydraulically, pressure oil is sucked or discharged through the suction / discharge ports 12a and 12b as shown in FIG. 6 (in FIG. 6, the suction / discharge port 12a is the suction side and the suction / discharge port 12b is the discharge side). The hydraulic cylinder 12 slides on the cylinder rod 13). In this structure, the hydraulic cylinder 12 slides on both sides at the same stroke by hydraulic pressure, and there is no difference in operating speed.

Next, a cylinder part bell crank 15 is pivotally supported on the lower part of the hydraulic cylinder 12, and an intermediate link 16 and a center bell crank 17 are pivotally connected to the cylinder part bell crank 15. The cylinder bell crank 15 rotates about a rotation fulcrum 15a as a fulcrum, and the center bell crank 17 rotates about a rotation shaft 18 as a fulcrum. The ends of the tie rods 19 that are directly connected to are connected to each other. In this way, the center bell crank 17 is rotated by the sliding of the hydraulic cylinder 12, the two tie rods 19 and 19 are accordingly rotated, and the front wheel F W is rotated. With the configuration of the hydraulic cylinder 12 as described above, the link mechanism from the cylinder bell crank 15 to the center bell crank 17 rotates left and right with the same stroke, so that the tie rods 19 on both sides can be rotated. There is no stroke difference, and therefore the front wheels FW turn left and right evenly.

The tractor has the power steering mechanism as described above. Next, a configuration for operating the front wheel speed increasing device using the power steering mechanism will be described with reference to FIG. Above the center bell crank 17, a gear box 20 for gearing with the same rotary shaft 18 as a rotary shaft is arranged. Conventionally, a gear operating shaft 20b is provided so as to project from a gear box 20 provided at the same position, and is transmitted to the gear operating shaft 20b through a transmission shaft from the handle H and steering shaft 8 to transmit the gear operating shaft 20b inside the gear box 20. In the present embodiment, the gear is driven by the rotating shaft 18 of the center bell crank 17 of the power steering mechanism, and the steering shaft 8 is provided on the gear operating shaft 20b. The structure of the transmission shaft is unnecessary.

A sliding shaft 20a, which slides back and forth by the rotation of an internal gear, is projectingly provided behind the gearbox 20 at the center of the machine body, and the operation arm 22a of the front wheel speed-increasing mission case 22 is provided. A front wheel speed-increasing operation rod 21 is provided between and. The front wheel speed-increasing operation rod 21 slides back and forth by the sliding shaft 20a, so that the operation arm 22a rotates forward and backward. On the other hand, power is transmitted from the mission case to the front wheel speed-increasing transmission case 22 via the front wheel drive shaft 24, and the front axles 23 are driven via internal gears. Then, the rotation of the operation arm 22a drives the gears for accelerating the front wheels in the front wheel accelerating mission case 22 to change the rotational speeds of the front axles 23 driven by the front wheel drive shaft 24. Then, the front wheel speed-up operation is performed. In this way, the structure is such that the front wheels are accelerated as the front wheels FW turn, and the front wheel speed increasing device is switched using the steering mechanism. It is different from the mechanism.

In addition to the above configuration, a power steering mechanism and a front wheel speed increasing configuration as shown in FIG. 7 can be considered by utilizing a configuration of a hydraulic cylinder that slides on a rod on both sides. That is, a hydraulic cylinder 12 having the same structure as that described above is arranged in the left-right direction at the center of the front part of the machine body, and both ends of the cylinder rod 13 are directly connected to the tie rods 19 ', 19' of the front wheels FW on both sides. The hydraulic cylinder 12 is fixed, and the cylinder rod 13 slides on both sides. With the sliding, the tie rods 19 'and 19' are directly rotated to rotate the front wheel FW. The power steering mechanism is configured to do so. With such a configuration, it is possible to realize left-right uniform turning, as in the power steering mechanism shown in FIGS.

A front wheel speed-increasing switching station 25 is arranged by connecting pivot points of both ends of the cylinder rod 13, and the gear box 20 is arranged above the hydraulic cylinder 12. The sliding shaft 20a is brought into contact with the front wheel speed increasing stay 25 so that the sliding shaft 20a slides due to the unevenness of the front wheel speed increasing stay 25. The front wheel speed-increasing device is configured by connecting the front wheel speed-increasing operation rod 21 to the sliding shaft 20a as described above. In this way, the front wheel speed increasing device is switched using the steering mechanism.

The power steering mechanism and the front wheel speed increasing mechanism of the tractor have been described above. Next, the structure of the operation box 6 disclosed in FIG. 1 will be described with reference to FIG. The operation box 6 has a gear shift operation lever and the like projecting from the upper portion, and rainwater and the like are easily infiltrated into the base end portion of such a lever. On the other hand, when an IC board is used for the operation system, its mounting position must be a place where such rainwater does not enter. In view of such a point, the operation box 6 of the present embodiment has an internal double structure. That is, the inside of the main body portion 6b whose upper portion is covered with the operation panel 6a is divided into the upper chamber portion and the lower chamber portion by the partition wall 6c, and the hem portion of the upper chamber portion penetrates into the upper chamber portion. Water drain holes 6d, 6d, ... for discharging rainwater and the like are opened. Since the upper part of the lower chamber is covered with the partition wall 6c and the lower part is covered with the back cover 26 to be hermetically sealed, infiltration of rainwater and the like is completely prevented. Therefore, by arranging the IC board 27 and the like in the lower chamber and arranging members such as a switch having strong water resistance in the upper chamber, the durability of each member for operation can be improved. .

Next, the configuration of the float 28 attached to the rear of the work machine R will be described with reference to FIGS. 9 and 10. In the work machine R, the subsidence phenomenon of the rotary occurs in the work in the wet field, and sufficient plowing work cannot be obtained. Therefore, in order to eliminate such a settlement phenomenon, the floats 28, 28 are attached to the rear part of the working machine R. In FIG. 9, a rear frame 30.30 is projected from the depth frame 29 fixed to the work machine R, a vertical frame 31.31 is vertically provided below the rear end thereof, and floats 28.28 are provided at the lower end thereof. Is supported by a pin. The rear frames 30 and 30 can be adjusted in height by the adjustment pins 30a and 30a, and the vertical frames 31 and 31 can be adjusted in vertical height by the adjustment pins 31a and 31a. In FIG. 10, a depth beam 32 is fixed to the rear end of the rear frame 30/30 in the left-right direction of the working machine R, and the vertical frames 31/31 are slidably attached to the depth beam 32. The float 28 and 28 can be adjusted to the left and right positions. As a result, the trail of the rear wheels of the tractor can be leveled with the float 28. In this way, the working machine R is prevented from sinking in wetlands, and the adverse effects such as the front rise of the tractor are eliminated, and even when the driving of the working machine R is stopped, the working machine R is submerged due to the buoyancy of the float. There is nothing to do.

[0018]

[Effect of device]

 The present invention has the following effects by being configured as described above. First, by arranging a bevel gearbox between the steering shaft and the hydraulic valve, the gear ratio of the bevel gearbox can be adjusted even in the case of a hydraulic cylinder structure with a small stroke that was too sensitive to handle operation. By doing so, it becomes possible to turn at a good steering wheel turning angle, and operability is improved. In addition, the installation of the bevel gearbox increases the degree of freedom in the installation position, and it is not necessary to place the hydraulic valve position below the handle. The risk can be reduced.

Further, the hydraulic cylinder adopts a system in which the cylinder slides on both the rods (or the rod slides on both the insides of the cylinders), so that the left and right turning speeds are the same, and the operability is improved. Is improved. Also, by arranging along the side frame, there is no interference with other members during operation.

Further, since the steering mechanism is used to perform the switching operation of the front wheel speed increasing device, the switching member for the front wheel speed increasing device, which has been conventionally required, is not required, and the degree of freedom in member arrangement is increased. Also, it leads to cost reduction.

[Brief description of drawings]

FIG. 1 is an overall side view of a tractor.

FIG. 2 is a plan view showing a configuration of a steering mechanism in a front portion of the machine body with respect to a handle portion.

FIG. 3 is a side view of the same.

FIG. 4 is a plan view showing the configuration of a steering mechanism at the front of the machine body.

FIG. 5 is a plan view showing a configuration of a front wheel speed increasing device at a front portion of the machine body.

FIG. 6 is a side view showing a configuration of a hydraulic cylinder for power steering.

FIG. 7 is a plan view showing a steering mechanism and a switch mechanism of a front wheel speed increasing device having another structure.

FIG. 8 is an assembled perspective view showing a configuration of an operation box.

FIG. 9 is a rear perspective view showing the configuration of the float attached to the rear part of the working machine.

FIG. 10 is a rear perspective view showing another configuration of the same.

[Explanation of symbols]

 H Handle FW Front wheel 1 Side frame 2 Front frame 8 Steering shaft 9 Bevel gear box 10 Transmission shaft 11 Hydraulic valve 12 Hydraulic cylinder 13 Cylinder rod 14 Fixing pin 15 Cylinder bell crank 16 Middle link 17 Center bell crank 18 Rotating shaft 19 Tie rod 20 gear box 21 front wheel speed increasing operation rod 22 front wheel speed increasing mission case

Claims (2)

[Scope of utility model registration request] 1. In a power steering mechanism of a tractor, a bevel gear box is arranged in the middle of a steering shaft connected to a hydraulic valve from a handle, and a hydraulic cylinder operated by operating the hydraulic valve is arranged along a side frame. And a center bell crank that connects the tie rods of the front wheels on both sides with the gear in the gear box of the front wheel speed-increasing device is interlocked via the link by the operation of the hydraulic cylinder. Power steering mechanism. 2. The power steering mechanism for a tractor according to claim 1, wherein the hydraulic cylinder for rotating the front wheels is of a double rod type, one end of a piston rod is fixed to the machine body, and the cylinder is configured to slide. Characteristic tractor power steering mechanism.