JP4263284B2 - Control device for engine rotation and vehicle speed of work vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a device for controlling engine rotation and vehicle speed in a work vehicle including a working device driven by engine output and a traveling device driven by an HST (hydrostatic transmission).
[0002]
[Prior art]
In a work vehicle having a working device driven by engine output and a traveling device driven by HST, generally, as shown in FIG. 7, an HST pump 3, a main pump 4, and a charging pump 5 are directly connected to the engine 1. Has been. The HST pump 3 is connected to the HST motor 6 in a closed circuit by a pair of main pipelines 31 and 32.
[0003]
The rotation speed of the engine 1 is controlled by operating the accelerator pedal 2, and the main pump 4 driven by the engine 1 supplies pressure oil to the main circuit 41 for driving the working device, and the charging pump 5 driven by the engine 1. Supplies pressure oil for control to a control circuit (not shown). The HST pump 3 driven by the engine 1 supplies pressure oil to the HST motor 6 to give rotation to drive the traveling device.
[0004]
The HST pump 3 is a variable displacement hydraulic pump, and the amount of discharged oil is adjusted by the inching lever 8 of the HST control valve 7. The inching lever 8 is connected to the link 10 of the brake pedal 9 by a rod 14, and when the brake 12 is operated via the brake cylinder 11 by operating the brake pedal 9, the inching lever 8 interlocks with the oil amount. Adjustments are made to control the speed of the travel device. In some cases, an operation lever is used instead of the accelerator pedal 2 or the brake pedal 9.
[0005]
Control of the working speed of the working device is performed by controlling the number of revolutions of the engine 1 by operating the accelerator pedal 2 and adjusting the amount of oil discharged from the main pump 4, but when the number of revolutions of the engine 1 increases, the main pump 4 increases the amount of oil discharged from the HST pump 3 as well, increasing the number of revolutions of the HST motor 6 and increasing the traveling speed of the work vehicle.
[0006]
Therefore, the operation of the accelerator pedal 2 can be performed when the work vehicle performs high-speed operation at high speed and performs low-speed operation at low speed. When it is desired to perform constant speed work while running at a variable speed, it cannot be controlled properly.
[0007]
For example, when the rotational speed of the engine 1 is increased for high-speed work, in order to reduce the traveling speed of the work vehicle, the inching lever 8 is moved by operating the brake pedal 9 and the HST pump 3 to the HST motor 6 It is necessary to adjust so as to reduce the supply amount of pressure oil. However, simultaneous operation of the accelerator pedal 2 and the brake pedal 9 is cumbersome and difficult to make delicate adjustments, and it is difficult to keep the traveling speed of the work vehicle constant, resulting in increased operator fatigue. Further, when the brake pedal 9 is always operated, the brake 12 is also operated, so that there is a problem that the brake 12 generates a large amount of heat and the durability is lowered.
[0008]
Therefore, as shown in FIG. 8, the inching lever 8 and the link 10 of the brake pedal 9 are connected by a cable 17, and a fixing lever 15 that can fix the inching lever 8 to an arbitrary position via the cable 16 is added. There has been proposed a hydraulic drive device for a work vehicle in which the traveling speed of the work vehicle is kept constant without operating the brake pedal 9 (see Japanese Utility Model Laid-Open No. 5-27422).
[0009]
[Problems to be solved by the invention]
According to the hydraulic drive apparatus described above, it is possible to perform variable speed work while traveling at a constant speed, but it is not possible to perform appropriate control when performing constant speed work while traveling at a variable speed.
[0010]
In such a case, the accelerator pedal 2 and the brake pedal 9 must be operated, which is troublesome. Even if it is not particularly necessary to control the vehicle speed, the accelerator pedal 2 must always be stepped on during work in order to obtain the engine rotation necessary for the work device, which places a heavy burden on the operator. Even if an operation lever is used in place of the accelerator pedal 2 and the brake pedal 9, there is a similar problem.
[0011]
The present invention solves such a problem in engine rotation and vehicle speed control of a work vehicle, and can control and hold the engine rotation and control the vehicle speed steplessly with a single operation lever. It is an object of the present invention to provide a control device for vehicle engine rotation and vehicle speed.
[0012]
[Means for Solving the Problems]
Engine and a vehicle speed control device for a work vehicle according to the present invention, a working device driven by the output of the engine, and a traveling device of the HST drive, an operating lever provided in order to control the engine speed and the vehicle speed an engine rotation control link being pivotally supported by the shaft of the operating lever, a cable interconnecting the links of the accelerator pedal which controls the governor lever of the engine rotation control link and the engine, the shaft of the operating lever a vehicle speed control link which is fixed, and a cable for connecting the inching lever of the vehicle speed control link and HST mutually, the relative rotation of the said vehicle speed control link and the engine rotation control link in a predetermined range a work vehicle having a Rukakarigo portion engaged with each other so as allowable, the engaging portion, the operating lever When the vehicle speed control link is rotated by operating the button, if the link is within the predetermined range, the link is rotated only on the vehicle speed control link without rotating the engine rotation control link. the when exceeding the predetermined range, the which the vehicle speed control link with the engine revolution control link is formed so as to rotate, the shaft of the operating lever, for the engine control and the operating lever retaining spring that holds a link to an arbitrary rotational position is provided.
[0013]
According to the engine rotation and vehicle speed control device for a work vehicle of the present invention, the engagement portion that engages the engine rotation control link and the vehicle speed control link with each other so as to allow relative rotation within a predetermined range. The engaging portion is formed so as to rotate the vehicle speed control link together with the engine rotation control link when the vehicle speed control link is rotated and the predetermined range is exceeded. Therefore, if you want to change the vehicle speed while performing constant speed work, operate the operating lever to rotate the engine rotation control link together with the vehicle speed control link via the engaging part, and link the accelerator pedal with the cable. By operating the engine, the engine can be set to the required rotation.
Then, the shaft of the operating lever, the holding spring to hold the operating lever and the engine rotation control link to an arbitrary rotation position is provided, the engine rotation control link is held in this position by retaining spring This makes it possible to perform constant speed work thereafter.
Further, this engaging portion is limited to the vehicle speed control link without rotating the engine rotation control link when it is within a predetermined range when the operation speed lever is operated to rotate the vehicle speed control link. Te is formed so as to pivot, where is rotated independently of the engine rotation control link by operating the operating lever within a predetermined range of relative rotation is allowed vehicle speed control link, a cable The vehicle speed can be controlled by operating the inching lever of the HST.
[0014]
Since the operating lever is also held at an arbitrary rotational position by the holding spring, when operating at a constant speed, the operating lever may be set to a position where the required vehicle speed is obtained and held.
Since the operator does not need to always step on the accelerator pedal during work, the burden is reduced.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
1 is a plan view of a control device for engine rotation and vehicle speed of a work vehicle according to an embodiment of the present invention, FIG. 2 is a side view of the control device for engine rotation and vehicle speed of the work vehicle, and FIG. 3 is an engine of the work vehicle. FIG. 4 is a sectional view taken along line AA of FIG. 2, FIG. 5 is an explanatory view of an engaging portion of the engine rotation control link, and FIG. 6 is a diagram of the vehicle speed control link. It is explanatory drawing of an engaging part.
[0016]
The work vehicle 50 includes a work device (not shown) driven by the output of the engine 51 and a travel device (not shown) driven by HST52. An operation console 53 is installed near the driver's seat of the work vehicle 50. A shaft 55 of an operation lever 54 for controlling the engine rotation and the vehicle speed is rotatably attached to the operation table 53, and an engine rotation control link 56 is pivotally supported by the shaft 55. A vehicle speed control link 57 is fixed to the shaft 55.
[0017]
One end of a push-pull cable 58 is attached to the tip of the engine rotation control link 56 with a spherical joint 59, and the other end of the push-pull cable 58 controls the governor lever 60 of the engine 51 via the pull cable 61. It is connected to the link 63 of the accelerator pedal 62.
[0018]
One end of a pull cable 64 is attached to the tip of the vehicle speed control link 57 with a spherical joint 65, and the other end of the pull cable 64 is connected to an inching lever 66 of the HST 52. A spring 72 that biases the inching lever 66 in the direction opposite to the pull cable 64 is attached.
[0019]
As shown in FIG. 4, the shaft 55 has a small-diameter portion 55A on the engine rotation control link 56 side and a large-diameter portion 55B on the vehicle speed control link 57 side, and is located between the operation console 53 and the engine rotation control link 56. Further, a thrust bearing 68 is provided between the friction plate 67, the large diameter portion 55B of the shaft 55, and the engine rotation control link 56. A friction plate 69 is also provided between the operation table 53 and the operation lever 54. A disc spring 70 is attached to the outer end portion of the shaft 55 and tightened with a nut 71. By this disc spring 70, the engine rotation control link 56 and the operation lever 54 (vehicle speed control link 57) are pressed against the friction plates 67 and 69, respectively, and can be held at an arbitrary rotational position by the friction force. .
[0020]
As shown in FIGS. 5 and 6, the engine rotation control link 56 is formed with a recess 56C, and the vehicle speed control link 57 is formed with a projection 57D. The recess 56C and the projection 57D are connected to the engine rotation control link 56. An engaging portion is formed to engage the vehicle speed control link 57 with each other. Here, the central angle θ ₂ of the convex portion 57D fitted in the concave portion 56C is about ½ of the central angle θ ₁ of the concave portion 56C. Accordingly, the engine rotation control link 56 and the vehicle speed control link 57 Are allowed to rotate relative to each other within a range of angles (θ ₁ −θ ₂ ).
[0021]
When it is desired to change the vehicle speed while performing constant speed operation, if the operation lever 54 is operated upward (clockwise in FIG. 2), the vehicle speed control link 57 is rotated clockwise through the shaft 55 to pull it. The cable 64 is pulled to operate the inching lever 66 of the HST 52 to the deceleration side, so that the vehicle speed is 0, that is, the work vehicle 50 does not move.
[0022]
When the operation lever 54 is further rotated from here, the convex portion 57D comes into contact with the end face of the concave portion 56C, and the engine rotation control link 56 rotates together with the vehicle speed control link 57 in the clockwise direction. Then, since the push-pull cable 58 rotates the link 63 of the accelerator pedal 62 in the same direction as when the accelerator pedal 62 is depressed, the governor lever 60 of the engine 51 is operated via the pull cable 61 to control the rotation of the engine 51. it can. Therefore, the engine is set to the required rotation. Since the engine rotation control link 56 is held at this position by the disc spring 70, the constant speed operation can be performed thereafter.
[0023]
When the engine 51 is controlled by the engine rotation control link 56, in order to prevent the work vehicle 50 from moving, the rotation of the engine rotation control link 56 starts after the vehicle speed becomes zero. There is a slight time difference.
When the operation lever 54 is operated downward (counterclockwise in FIG. 2) after setting the engine to the required rotation, the vehicle speed control link 57 is rotated counterclockwise in FIG. The pulling force of the cable 64 is weakened, and the inching lever 66 of the HST 52 is actuated to the speed increasing side by the spring 72, thereby increasing the vehicle speed. At this time, since the engine rotation control link 56 can rotate independently of the engine rotation control link 56 within the range of the angle (θ ₁ −θ ₂ ), the operation lever 54 is operated within this range. Thus, the vehicle speed can be controlled steplessly while the engine rotation is kept constant.
[0024]
Since the thrust bearing 68 is provided, the vehicle speed control link 57 can be freely rotated in a state where the engine rotation control link 56 is pressed against the friction plate 67 so as not to move by the force of the disc spring 70. .
Since the operating lever 54 is also held at an arbitrary rotational position by the disc spring 70 and the friction plate 69, the operating lever 54 may be set to a required vehicle speed and held when traveling at a constant speed.
[0025]
The operator does not have to step on the accelerator pedal 62 at all times during the operation, and only has to operate one operation lever 54, so the burden is reduced.
The inching lever 66 is connected to a brake pedal (not shown). When necessary, the inching lever 66 is braked by depressing the brake pedal, and the work vehicle 50 can be stopped at any time.
[0026]
【The invention's effect】
As described above, in the engine rotation and vehicle speed control device for a work vehicle according to the present invention, the engine rotation can be controlled and held by a single operation lever, and the vehicle speed can be controlled steplessly. Since it is not necessary to perform a plurality of control operations at the same time, it is only necessary to operate one operation lever, so that the burden on the operator is reduced.
[Brief description of the drawings]
FIG. 1 is a plan view of a control device for engine rotation and vehicle speed of a work vehicle according to an embodiment of the present invention.
FIG. 2 is a side view of a control device for engine rotation and vehicle speed of a work vehicle.
FIG. 3 is an enlarged plan view of a main part of a control device for engine rotation and vehicle speed of a work vehicle.
4 is a cross-sectional view taken along line AA in FIG.
FIG. 5 is an explanatory diagram of an engaging portion of an engine rotation control link.
FIG. 6 is an explanatory diagram of an engaging portion of a vehicle speed control link.
FIG. 7 is a circuit diagram showing a configuration of a conventional hydraulic drive device for a work vehicle.
FIG. 8 is a circuit diagram showing a configuration of a conventional hydraulic drive device for a work vehicle.
[Explanation of symbols]
50 work vehicle 51 engine 52 HST
53 Operation console 54 Operation lever 55 Shaft 56 Engine rotation control link 56C Recess 57 Vehicle speed control link 57D Projection 58 Push-pull cable 60 Governor lever 61 Pull cable 62 Accelerator pedal 63 Link 64 Pull cable 66 Inching lever 67 Friction plate 68 Thrust bearing 69 Friction plate 70 Belleville spring 71 Nut 72 Spring

Claims (1)

A working device driven by the output of the engine, and a traveling device of the HST drive, an operating lever provided in order to control the engine speed and the vehicle speed, engine speed control, which is pivotally supported by the shaft of the operating lever links and, a cable interconnecting the links of the accelerator pedal which controls the governor lever of the engine rotation control link and the engine, and a vehicle speed control link which is fixed to the shaft of the operating lever, vehicle speed control link and a cable connecting the inching lever HST mutually, and said Rukakarigo portion engaged with each other so that said vehicle speed control link between the engine rotation control link to allow the relative rotation of a predetermined range A work vehicle having
When the vehicle speed control link is rotated by operating the operation lever when the engagement portion is within the predetermined range, the vehicle speed control is performed without rotating the engine rotation control link. It is formed so as to rotate the vehicle speed control link together with the engine rotation control link when the predetermined range is exceeded, and the vehicle speed control link is rotated.
Wherein the operating lever shaft, the engine rotation and the vehicle speed control device for a work vehicle, characterized in that the retaining spring for holding said engine control link and the operation lever at an arbitrary rotational position is provided.

Images