JP3365408B2 - Tractor turning control - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tractor turning control device. 2. Description of the Related Art In recent years, a high / low speed switching device has been incorporated into a front wheel drive system of a tractor so that the front and rear wheels have substantially the same peripheral speed when traveling straight, and the front wheel has a peripheral speed that is equal to that of the rear wheels when turning. There is known a configuration in which a high-speed state is created by approximately twice as high. Also, in tractors and the like, braking devices for braking the rear wheels are independently provided on the left and right, and these operate a pair of left and right brake pedals provided at the feet of the driver to simultaneously operate the left and right brake pedals.
Alternatively, it can be braked individually. [0003] Except for traveling on a road moving at a high speed, the left and right brake pedals are not connected, and during general tilling work, the rear wheel inside the turning is braked to turn the body with a small turning radius. [0004] When tilling work or the like is performed using a tractor having a high / low speed switching device, and if it is desired to turn the body with a minimum turning radius, the front wheel drive system is driven at a high speed. In addition to the state, the brake device must be operated by depressing the brake pedal inside the turn, and such operation is complicated because it involves the operation of the steering handle and the hydraulic lever when turning at the field end. It is a burden for the driver to turn while continuing to depress the brake pedal when turning at the ridge. [0005] The brake device and the height changing device are mutually operated to assist the turning of the tractor. However, if a steering angle detecting device or a control means for operating both devices is separately provided, a combination is provided. There is a problem that the operation timing is easily shifted due to an attachment error, individual difference, and the like, and there is a problem that smooth turning is prevented, and a problem that costs are increased. SUMMARY OF THE INVENTION The present invention proposes to solve the above-mentioned problems, and employs the following technical means. That is, brake devices 37 , 37 for transmitting the rotational power of the engine 2 to the rear wheel differential device 6 in the transmission case 3 and braking the left and right rear wheels respectively on the left and right output shafts 32 , 32 of the rear wheel differential device 6. Along with
A high-low speed switching device for switching the rotational power from a low speed to a high speed is provided on the power transmission upstream side of the rear wheel differential device 6 , and the rotational power branched from the rear wheel drive system is transmitted to the front wheels via the high-low speed switching device. In the tractor 1 configured to transmit, the tractor 1 includes a steering angle detection device 47 that detects a steering angle of a front wheel, and the left and right brake devices 37 and 3.
And a brake valve 3 for operating each of the brake valves 7
The pressure control for the pressure to operate the 7 and 37 to a predetermined pressure
A valve 41 and a control valve for switching the high / low speed switching device to high / low
Provided a 25, a high speed when the angle state where the front wheel steering angle approaches the minimum turning radius steering angle detector 47 detects the turn-locus inner side of the brake device 37 is operated at a predetermined pressure, the high and low speed switching device Power is transmitted to the front wheels by switching to the side
The tractor turning control device is characterized in that one control means 50 for controlling the tractor is provided. An embodiment of the present invention will be described below based on an embodiment shown in the drawings. First, a description will be given of the structure. Reference numeral 1 denotes a tractor, which has an engine 2 mounted on a front portion of a machine frame, and has a rear wheel mounted on a rear end of a transmission shaft 5 which is mounted in a transmission case 3 in a rearward direction. A bevel pinion 8 meshing with the bevel gear 7 of the differential device 6 is attached. A pair of transmission gears 11 and 12 having different numbers of teeth for transmission to a clutch (hereinafter referred to as a front wheel clutch) 10 of a front wheel drive system are attached. As the front wheel clutch 10, a two-speed wet multi-plate clutch is adopted. A low-speed passive plate 15,... And a high-speed passive plate 16 are provided on both sides of a clutch shaft 14 parallel to the transmission shaft 5. , A driving plate 19 corresponding to the low-speed passive plate 15, a low-speed clutch gear 20, and a driving plate 22 corresponding to the high-speed passive plate 16, , A high-speed clutch gear 23 is provided. The clutch gears 20 and 23 are
With respect to the transmission gears 11, 1
2 meshes with each other. The front wheel clutch 10 is driven by a hydraulic switching valve 25 and a pressure control valve 26 to transmit the transmission gear 1.
1 is switched to a low speed at which the clutch gear 20 is meshed, a high speed at which the transmission gear 12 is meshed with the clutch gear 23, and a neutral stage in which all are disconnected. The clutch shaft 14 is connected to a joint 28
Drive shaft 3 that transmits rotational power to the front wheels via the
Connected to 0. The shaft 32 (L,
R), a wheel pinion 35 (L, R) meshing with the wheel gears 33 (L, R) of the left and right rear wheels, and a brake plate 38 (L, R) of a brake device 37 (L, R) are attached. I have. The brake shoes 39 (L, R) can be individually driven by brake cylinders 42 (L, R) operated under the control of the switching valve 40 and the pressure control valve 41, and the rear wheels on any side can be used as necessary. You can put a brake on The tractor 1 is provided with a steering control device 44 for controlling the steering of the traveling device. The steering control device 44 is configured as shown in FIG. 3, and detects a steering angle of the front wheels, that is, a steering angle by a steering sensor 47 provided below the intermediate shaft 46 connected to the steering shaft 45. This is processed by the controller 50, and an output signal is output to the switching valve 40 and the pressure control valve 41. Referring specifically to FIG. 4, A and B are rotation centers at the time of a weak turn and a sharp turn, respectively, C and D are center points of a rear axle and a front axle, respectively, and angles θ1, θ2, θ3.
Is a set angle serving as a control reference. When the detected steering angle detected by the steering sensor 47 is within the range of θ1, the front wheel clutch 10 is kept neutral, and the vehicle travels by driving only the rear wheels. When the detected steering angle is in the range from θ1 to θ2, the clutch 10 is engaged at a low speed. At this time, the rotation ratio of the front and rear wheels is R1: R
2, the front wheels rotate slightly faster than the rear wheels. When the detected steering angle is in the range from θ2 to θ3, the front wheel clutch 10 is switched at high speed.
At this time, the rotation ratio of the front wheel and the rear wheel is R3: R4, and the front wheel rotates considerably faster than the rear wheel. Therefore, even if the vehicle turns sharply, the rear wheel does not slip and the vehicle runs stably. Can be. Θ3 is the steering angle when turning with the minimum turning radius. When the detected steering angle approaches this, the brake device inside the turn is activated to apply a brake on that side to assist a sharp turn. . In this case, since the front wheel clutch 10 is switched to the high speed side, the front wheel does not act as a brake for the rear wheel, and the vehicle can turn quickly. As described above, according to the present invention, the rotational power of the engine 2 is transmitted to the rear wheel differential device 6 in the transmission case 3 , and the left and right output shafts 32 , 32 of the rear wheel differential device 6 are left and right. Brake devices 37 , 37 for separately braking the rear wheels are provided, and a high-low speed switching device for switching the rotational power from low speed to high speed is provided on the power transmission good side of the rear wheel differential device 6 , and the rear wheel drive system A tractor configured to transmit the branched rotational power to the front wheels via the high / low speed switching device
In 1, the tractor 1 has a steering angle detector 47 for detecting a front wheel steering angle, the left and right brake devices 37, 37 and the control valve 40 for each separate operation, the brake
Pressure at which the pressure for operating the devices 37, 37 is set to a predetermined pressure
A force control valve 41 and a control valve 25 for switching the high / low speed switching device to a high / low position are provided, and when the steering angle detection device 47 detects an angle state in which the steering angle of the front wheels approaches a minimum turning radius. ,
Activate the brake device 37 inside the turn at a predetermined pressure,
Switch the high / low speed switching device to the high speed side to transmit power to the front wheels
Since one control means 50 is provided to control the vehicle in a turning state, the high / low speed switching device is automatically switched to the high speed side at the time of turning, and the brake device 37 for braking the rear wheel inside the turning is also a pressure control valve. Automatically operating at the operating pressure set at 41, the turning operation is simpler and easier than in the conventional device. Also, at the time of turning, the brake device 37
And the high / low speed switching device are operated by one control means 50.
So, the front wheel also shift in operation timing is less likely to occur because the pivot while being driven, high and low speed switching retrofits the brake device 37
The aircraft can be turned smoothly by the mutual operation of the
Also, the manufacturing cost can be reduced.

[Brief description of the drawings] FIG. 1 is a side view of a tractor. FIG. 2 is an explanatory diagram of a main part. FIG. 3 is a block diagram of a steering control device. FIG. 4 is an explanatory diagram of steering control. [Explanation of symbols] 1 tractor 2 Engine 3 Mission case 10 Front wheel clutch 37 Brake equipment 44 Steering control device 47 Steering sensor 50 control means (controller)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B62D 11/00

Claims (1)

(57) [Claims] A brake device for transmitting the rotational power of the engine 2 to a rear wheel differential device 6 in the transmission case 3 and braking the left and right rear wheels separately on left and right output shafts 32 of the rear wheel differential device 6.
37 , 37, and a high / low speed switching device for switching the rotational power from a low speed to a high speed is provided on the upper side of the power transmission of the rear wheel differential device 6 , and the rotational power branched from the rear wheel drive system is switched to the high / low speed. In the tractor 1 configured to transmit to the front wheels via a device, the tractor 1 includes a steering angle detection device 47 that detects a steering angle of the front wheels, and the left and right brake devices 37, 37 that are separately operated. Control valve 40 to actuate, and pressure to actuate brake devices 37, 37
And a control valve 25 for switching the high / low speed switching device between high and low, and the steering angle detection device 47 detects an angle state in which the steering angle of the front wheels approaches the minimum turning radius. When it is detected, the brake device 37 inside the turn is
Operates at a constant pressure and switches the high / low speed switching device to the high speed side
Control means for controlling power to be transmitted to the front wheels
A turning control device for a tractor, wherein 50 is provided.