JP2010078089A - Continuously variable running controlling device for working vehicle - Google Patents

Abstract

An object of the present invention is to provide a work vehicle capable of ensuring stable traveling at low speeds and sufficient acceleration at high speeds while ensuring simple vehicle speed adjustment operation and efficient engine control by a pedal operation. The object is to provide a continuously variable speed travel control device.
The continuously variable transmission work vehicle performs the continuously variable transmission mechanism control and the engine throttle control so as to control the traveling vehicle speed and the engine speed in accordance with the depression position of the accelerator pedal. The engine control range (F1) in which the engine changes from idling to the maximum rotational speed and the continuously variable transmission control range (F2) in which the continuously variable transmission mechanism (1) changes from the stop speed to the maximum vehicle speed. And the continuously variable transmission control range (F2) is set larger than the engine control range (F1).
[Selection] Figure 7

Description

  The present invention relates to a continuously variable traveling control device for a work vehicle that controls a traveling vehicle speed and an engine speed corresponding to a depression position of an accelerator pedal.

2. Description of the Related Art A continuously variable traveling control device for a working vehicle that controls a traveling vehicle speed and an engine speed in correspondence with a depression position of an accelerator pedal is known. As shown in the example of Patent Document 1, this continuously variable speed travel control device controls the rotation of the trunnion shaft of the hydrostatic continuously variable transmission mechanism in correspondence with the depression position of the accelerator pedal, and from the stop speed to the highest speed. It is possible to adjust the vehicle speed continuously within the range up to and adjust the engine throttle from idling to maximum speed. Therefore, only by depressing the accelerator pedal, it is possible to suppress unnecessary engine rotation when the vehicle is stopped, and to secure the necessary power at high speed and to efficiently operate the work vehicle.
JP-A-2005-343187

  However, the continuously variable travel control device having the above-described configuration obtains sufficient travel power because the engine speed is low in the low vehicle speed range because the vehicle speed and the engine rotation gradually change according to the depression amount of the accelerator pedal. In addition to causing instability of work travel, the engine torque is reduced at the maximum vehicle speed, and sufficient acceleration at high speed cannot be ensured, resulting in disruption of road traffic.

  The problem to be solved is to ensure a stable driving at low speeds and sufficient acceleration at high speeds while ensuring simple vehicle speed adjustment operation of the work vehicle by pedal operation and efficient engine control. An object of the present invention is to provide a continuously variable speed travel control device for a work vehicle.

  According to a first aspect of the present invention, there is provided a continuously variable traveling control device for a work vehicle that performs continuously variable transmission mechanism control and engine throttle control so as to control the traveling vehicle speed and the engine speed in correspondence with a depression position of an accelerator pedal. For the operation from the start of depression of the accelerator pedal, an engine control range where the engine changes from idling to the maximum speed and a continuously variable transmission control range where the continuously variable transmission mechanism changes from the stop speed to the maximum vehicle speed are provided separately. The continuously variable transmission control range is set larger than the engine control range.

  With the above configuration, the traveling vehicle speed and the engine speed increase according to the accelerator pedal depressing operation, and the continuously variable transmission mechanism reaches the maximum vehicle speed after reaching the maximum speed. Sufficient driving power can be secured with a simple pedal depression.

  According to a second aspect of the present invention, there is provided a continuously variable traveling control device for a work vehicle that performs continuously variable transmission mechanism control and engine throttle control so as to control the traveling vehicle speed and the engine speed in accordance with the depression position of an accelerator pedal. For the operation from the start of depression of the accelerator pedal, a continuously variable transmission control range in which the continuously variable transmission mechanism changes from the stop speed to the maximum vehicle speed and an engine control range in which the engine changes from idling to maximum torque are individually provided. This engine control range is set to the same range as the continuously variable transmission control range.

  According to the second aspect of the present invention, the engine speed and the traveling vehicle speed increase according to the depression operation of the accelerator pedal, and the continuously variable transmission mechanism reaches the maximum vehicle speed at the pedal position where the engine has the maximum torque. Sufficient acceleration in high speed traveling is ensured.

  In the continuously variable transmission control device according to the first aspect, the continuously variable transmission mechanism reaches the maximum vehicle speed after the engine reaches the maximum rotation speed in response to the depression operation of the accelerator pedal. Sufficient driving power can be secured by depressing the pedal, so that stable driving can be performed over a wide range of vehicle speeds necessary for working while ensuring simple vehicle speed adjustment operation and efficient engine control of the working vehicle by pedal operation. It becomes possible.

  According to the continuously variable transmission control device of the second aspect, since the continuously variable transmission mechanism has the maximum vehicle speed at the pedal position where the engine has the maximum torque according to the depression operation of the accelerator pedal, the simple vehicle speed of the work vehicle by the pedal operation can be reduced. While ensuring the adjustment operation and efficient engine control, sufficient acceleration in high-speed traveling is ensured and road traffic can be handled.

Embodiments specifically configured based on the above technical idea will be described below with reference to the drawings.
A multipurpose work vehicle as an example of a continuously variable work vehicle to which the present invention is applied will be described. As shown in FIG. 1, a plan view (a) and a side view (b) of this work vehicle are monocoque. The left and right front wheels 8 and 8 and the left and right rear wheels 9 and 9 are supported by the frame so that they can be steered. The configuration of a general work vehicle is reversed, that is, the engine 6 is arranged at the rear of the body, and the transmission 14 is installed. Place it in front of the aircraft. The control part 2d is formed at the front part of the machine body, the loading platform 2t is formed at the rear part, the PTO shaft 13 is provided at the front part of the machine body as working machine power, and the vehicle height detection mechanism 2h is formed in a drooping manner at the machine body intermediate position. .

  Further, as shown in FIG. 1C, the steering part 2d is provided with a steering handle R by standing a handle column 2c, and a forward / reverse switching lever S is provided on the side of the handle column 2c. In the base, an accelerator pedal 5 for adjusting the vehicle speed is arranged at the right side, and operating means such as a brake pedal B and a clutch pedal C are arranged at the left side.

  As will be described in detail later, the transmission 14 includes a hydrostatic continuously variable transmission mechanism 1 and a gear-type transmission mechanism 14 a, which are abbreviated as “HST”, provided in series to the front and rear wheels 8 and 9 and the PTO output shaft 13. Transmits driving force. When the accelerator pedal 5 is stepped on, the power from the engine 6 is changed by the continuously variable transmission mechanism 1 in the transmission 14, and further changed by the transmission mechanism 14a, so that the rear wheels 9, 9 or the rear wheels 9, 9 and the front wheels are changed. 8 and 8, the aircraft moves forward or backward. Further, when the brake pedal B is depressed, the disc brakes (not shown) of the front wheels 8 and 8 and the rear wheels 9 and 9 are operated, and the trunnion shaft H of the variable hydraulic pump of the continuously variable transmission mechanism 1 is driven by the electric drive unit 1a. By returning to neutral, the output from the fixed hydraulic motor of the continuously variable transmission mechanism 1 is stopped. If the accelerator pedal 5 and the brake pedal B are depressed at the same time, the brake pedal B is given priority.

  Various work machines are connected to the PTO shaft 13 to enable multipurpose work. For example, a road cleaning machine is provided to perform road cleaning, a lawn mower is attached to perform lawn mowing work, or a snow plow is provided to perform snow removal work.

Next, the internal structure of the mission case 14 will be described with reference to FIGS.
As shown in FIG. 2, the transmission case 14 has a configuration in which four hollow cases of a front case 15, a connecting case 16, an intermediate case 17, and a rear case 18 are connected, and an engine 6 is connected to an input shaft 19 that is pivotally supported by the rear case 18. , The rotation of the input shaft 19 is transmitted to the first relay shaft 23 by the speed increasing gears 21 and 22 in the input case 20, and further increased by the speed increasing gears 24 and 25. The hydraulic input shaft 38 of the continuously variable transmission mechanism 1 is spline fitted to the gear 25. The connecting case 16 connects the conventional front case 15 and the intermediate case 17 to lengthen the mission case 14, and the front case 15, the intermediate case 17, and the rear case 18 are shared with the conventional mission case, so that the production cost is increased. Can be lowered.

  The input case 20 including the speed increasing gears 21 and 22 and the speed increasing gears 24 and 25 is provided to increase the output rotation speed of the engine 6 so as to enable high speed running. The transmission mechanism can be stored in the case 14. As shown in FIG. 4, if the input case 20 is a sealed case and oil is supplied from an oil supply pipe that leads to the outside of the transmission case 14, the transmission gears 21, 22, 24, and 25 are repaired when the transmission is repaired. Since only the input case 20 can be removed without draining the oil in the case 14, the work becomes easy.

Inside the continuously variable transmission mechanism 1, the output is largely steplessly changed by hydraulic transmission and is output to two shafts of the PTO drive shaft 26 and the travel drive shaft 27.
A PTO gear shaft 28 is connected to the PTO drive shaft 26, a gear 29 of the PTO gear shaft 28 and a gear 31 that is loosely fitted to the second relay shaft 30 are engaged, and a PTO clutch in which the gear 31 is mounted on the PTO shaft 32. It meshes with 34 gears 33. The PTO clutch 34 interrupts rotation transmission from the gear 33 to the PTO shaft 32.

A PTO extension shaft 35 is connected to the PTO shaft 32, and a gear 36 of the PTO extension shaft 35 is engaged with a clutch gear 37 spline-fitted to the PTO output shaft 13 to drive the PTO output shaft 13. (See Figure 2)
The details of the PTO clutch 34 are shown in FIG. 5. When the clutch is engaged, the clutch disc 88 is connected and the casing 86 is rotated and transmitted, but when the clutch is disengaged, the clutch disc 88 is separated by the pressure of the return spring 87 and the casing 86 is separated. Make it free. At this time, a locking ring 85 that contacts the boss 81 of the connecting case 16 is attached to the outer periphery of the casing 86 in order to prevent the casing 86 from being attached.

  A third relay shaft 39 is connected to the travel drive shaft 27, and gears 41 and 42 fixed to the third relay shaft 39 are engaged with each other and transmitted to the fourth relay shaft 43. A main gear shaft 44 is connected to the fourth relay shaft 43.

A large gear 45 and an intermediate gear 46 are integrally fixed to the main gear shaft 44, and a sub gear shaft 47 is separated and supported rotatably on the extension of the main gear shaft 44. A small gear 48, a large gear 74, and a travel transmission gear 75 are integrally fixed to the sub gear shaft 47. Accordingly, the large gear 45 and the middle gear 46 rotate in the same direction, and the small gear 48, the large gear 74, and the travel transmission gear 75 receive rotation from a clutch gear 77 described later. (See Figure 5)
The large gear 45 meshes with the gear 50 of the high-speed hydraulic clutch YH attached to the clutch shaft 49, the middle gear 46 meshes with the gear 53 of the low-speed hydraulic clutch YL attached to the clutch shaft 49, and the rotation of the main gear shaft 44 causes the clutch shaft 49 to rotate. To high speed or low speed.

  A spline shaft 76 is spline-fitted on the extension of the clutch shaft 49, and a clutch gear 77 is spline-fitted on the spline shaft 76 to transmit the rotation of the clutch shaft 49 to the clutch gear 77. Further, the boss portion 81 of the connecting case 16 that supports the clutch shaft 49 is provided with hydraulic holes 82, 83, 84 that communicate with the hydraulic holes of the clutch shaft 49, and hydraulic oil is supplied to the high-speed hydraulic clutch 51 and the low-speed hydraulic clutch 52. I am trying to send it.

  A large gear 78 and a small gear 73 are formed in the clutch gear 77, and the large gear 78 meshes with the small gear 48 of the sub gear shaft 47 to increase the transmission speed to form a high speed gear clutch GH, or the small gear 79 is a sub gear. The low speed gear clutch GL is configured by meshing with the large gear 74 of the shaft 47 and decelerating, or the gear shift clutch 3 is configured such that the large gear 78 and the small gear 79 are both turned to turn off the power. Yes.

  The travel transmission gear 75 of the clutch shaft 49 is engaged with the travel gear 56 spline-fitted to the bevel gear shaft 62 loosely fitted to the spline shaft 76 to drive the bevel gear shaft 62. The bevel gear 63 of the bevel gear shaft 62 transmits the driving force to the bevel gear attached to the axle of the front wheel 8.

  The bevel gear shaft 62 is a four-speed transmission from the high speed hydraulic clutch YH to the large gear 78 of the clutch gear 77 and the small gear 48 of the sub gear shaft 47, or the small gear 79 of the clutch gear 77 and the sub gear shaft 47 of the sub gear shaft 47. Third gear by transmission to the large gear 74, second gear by transmission from the low speed hydraulic clutch YL to the large gear 78 of the clutch gear 77 and the small gear 48 of the sub gear shaft 47, or small gear of the clutch gear 77 from the low speed hydraulic clutch YL. 79 and the sub gear shaft 47 are rotated at any one speed by transmission to the large gear 74.

  Further, the rotation of the bevel gear shaft 62 is transmitted from the traveling gear 56 to the small gear portion 57 of the large and small gear 59 attached to the PTO shaft 32, and is further appropriately controlled by the clutch gear 60 of the rear wheel drive shaft 61 engaged with the large gear portion 58. The driving force can be transmitted to the rear wheel 9.

Since the traveling gear 56 is transmitted to the bevel gear shaft 62 and is transmitted to the rear wheel drive shaft 61 via the large and small gears 59, the transmission configuration is simplified to prevent it from becoming longer in the front-rear direction.
Note that either the high-speed hydraulic clutch YH or the low-speed hydraulic clutch YL is kept on via a solenoid in response to a control signal from the controller. A switch B for detecting depression of the brake pedal is provided. In response to the depression signal, the power to the solenoids of the high-speed hydraulic clutch YH and the low-speed hydraulic clutch YL is cut off so that both clutches 51 and 52 are neutral. By applying the brake in this neutral state, it can be quickly stopped and the gear shift clutch 3 can be switched smoothly.

  The boss portion 81 of the connecting case 16 that supports the clutch shaft 49 is provided with hydraulic holes 82, 83, 84 that communicate with the hydraulic holes of the clutch shaft 49, and hydraulic oil is supplied to the high-speed hydraulic clutch YH and the low-speed hydraulic clutch YL. I am trying to send it.

  FIG. 6 shows the shift lever 4, and the gear shift clutch 3 is shifted to the high-speed gear clutch or the low-speed gear clutch by rotating the shift groove 96 from the center neutral position N to the front and rear H and L. When the speed increasing button 81 provided on the head of the grip 80 of the speed change lever 4 is pressed, the high speed hydraulic clutch YH is engaged, and when the speed reducing button 82 is pressed, the low speed hydraulic clutch YL is engaged.

  Further, sensors 90H and L for detecting the position of the speed change lever 4 are provided in the speed change groove 96 so that when the speed change lever 4 moves from the low speed position L to the high speed position H, it is turned off even if the high speed hydraulic clutch YH is on. When the low speed hydraulic clutch YL is turned on to become the third speed and moved from the high speed position H to the low speed position L, the low speed hydraulic clutch YH is turned on even if the low speed hydraulic clutch YL is turned on, and the second speed is turned on. The microcomputer is controlled so that When the high-speed hydraulic clutch YH is engaged, if the accelerator pedal 5 is depressed 3/4 or more and the continuously variable transmission mechanism is at a high speed, the speed change shock is reduced once. Further, when the lever 4 presses the deceleration button 82 at the low speed position L, the first speed is achieved, and when the lever 4 presses the acceleration button 81 at the high speed position H, the fourth speed is achieved.

(Shift control)
Next, the shift control will be described.
The continuously variable speed travel control device is configured by a control unit that performs continuously variable speed mechanism control and engine control so as to control the traveling vehicle speed and the engine speed in accordance with the depression position of the accelerator pedal. As shown in FIG. 7, the control characteristic by the control unit is as follows. As shown in FIG. 7, the operation from the start of depression of the accelerator pedal is performed at two depression positions P0 and P1 where the engine 6 changes from idling to the maximum rotation speed. An engine control range F1 that extends and a continuously variable transmission control range F2 that extends to two step positions P0 and P2 in which the continuously variable transmission mechanism changes from the stop speed to the maximum vehicle speed are provided. It is smaller than F2, that is, the depression start position P0, the maximum engine speed position P1, and the maximum vehicle speed position P2 of the continuously variable transmission mechanism are set in this order.

  By configuring the above control characteristics in the control unit, the engine speed and traveling vehicle speed increase in response to the accelerator pedal depression, and the continuously variable transmission mechanism reaches the maximum vehicle speed after the engine reaches the maximum speed. Therefore, the traveling power can be secured with a slight depression of the pedal corresponding to the rated rotational speed before the engine reaches the maximum rotational speed, so that stable traveling is possible over a wide vehicle speed range.

  In this case, the engine control range F1 is narrowed to be less than half of the continuously variable transmission control range F2, and the engine speed is increased to the maximum number of revolutions with a small stepping operation to effectively use the ability of the continuously variable transmission mechanism. be able to. Further, by matching the rated engine speed position and the minimum vehicle speed position necessary for work travel, traveling power can be secured over the entire work vehicle speed range.

  Next, as an example of handling load at high speed, the control characteristic by the control unit is as follows. As shown in FIG. 8, the continuously variable transmission mechanism is used for the operation from the start of depression of the accelerator pedal. Separately, a continuously variable transmission control range F2 that extends from two depressing positions P0 and P2 that changes from the stop speed to the maximum vehicle speed, and an engine control range F3 that extends from two depressing positions P0 and P3 where the engine changes from idling to maximum torque The engine control range F3 is set to the same range as the continuously variable transmission control range F2, that is, the maximum rotation speed of the engine with the maximum vehicle speed position P2 of the continuously variable transmission mechanism and the maximum torque position P3 of the engine as the same pedal depression position. The maximum pedal depression range is set up to several positions P1.

  By configuring the control characteristic in the control unit, the engine speed and the traveling vehicle speed increase in accordance with the accelerator pedal depression operation, and the continuously variable transmission mechanism has the maximum vehicle speed P2 at the pedal position P3 where the engine has the maximum torque. As a result, sufficient acceleration in high-speed driving is ensured, so that simple vehicle speed adjustment operation of the working vehicle by pedal operation and efficient engine control are ensured, and traffic on the road is not disturbed. It can correspond to traveling.

(Sub-shift compatible)
Next, regarding the control at the time of switching of the auxiliary transmission mechanism, as shown in the timing chart of FIG. 9, when the auxiliary transmission position is switched from the low speed L to the high speed H, the trunnion angle is not maintained as it is at T1. By performing the step shift control and performing the shift control after a predetermined time has elapsed thereafter, it is possible to improve the operability when the engine speed is reduced due to the load fluctuation at the time of the sub shift switching.

(Shift regulation)
Next, for continuously variable transmission mechanism control, as shown in the shift restriction diagram of FIG. 10, the control angle of the trunnion is restricted according to the traveling vehicle speed, and the control angle of the trunnion angle is controlled in a small range at low speeds. Acceleration can be improved by reducing the load on the engine.
In this case, by selecting a plurality of restriction patterns A to C so as to be switchable, appropriate selection according to the work content such as emphasis on horsepower and energy saving becomes possible.

  Further, a switch called a kick down switch is provided, and the control range of the continuously variable transmission mechanism is set to a restriction angle smaller than the maximum control angle A of the trunnion as shown in the control characteristic diagram of FIG. 11 corresponding to this switch operation. By being configured to be switchable, the load can be reduced while the switch is being pressed during heavy loads, so workability can be improved.

  In this case, as shown in the control characteristic diagram (a) and the system configuration diagram (b) of FIG. It is possible to change the control characteristics according to the load of the vehicle to ensure optimum traveling performance.

Plan view (a), side view (b) and main part perspective view (c) of multi-purpose work vehicle Transmission axis development Fig. 2 is an exploded view of the main axis of the transmission of Fig. 2 FIG. 2 is an enlarged view of a continuously variable transmission portion of the transmission of FIG. FIG. 2 is an enlarged view of the transmission mechanism of the transmission of FIG. Perspective view of transmission lever Pedal operation characteristic diagram example Pedal operation characteristic diagram example Timing chart of control at the time of sub-shift switching Shift regulation diagram Control characteristic diagram Control characteristic diagram (a) and system configuration diagram (b)

Explanation of symbols

1 Hydrostatic continuously variable transmission mechanism (HST)
1a Electric drive unit 5 Accelerator pedal 6 Engine F1 Engine control range F2 Continuously variable control range F3 Engine control range H Trunnion shaft P0 Stepping start position P1 Maximum speed position P2 Maximum vehicle speed position P3 Maximum torque position

Claims (2)

In a continuously variable traveling control device for a work vehicle that performs continuously variable transmission mechanism control and engine throttle control so as to control the traveling vehicle speed and the engine speed in correspondence with the depression position of an accelerator pedal,
Regarding the operation from the start of depression of the accelerator pedal, the engine control range (F1) in which the engine changes from idling to the maximum speed, and the continuously variable transmission control range in which the continuously variable transmission mechanism (1) changes from the stop speed to the maximum vehicle speed. (F2) is provided separately, and the continuously variable transmission control range (F2) is set larger than the engine control range (F1). In a continuously variable traveling control device for a work vehicle that performs continuously variable transmission mechanism control and engine throttle control so as to control the traveling vehicle speed and the engine speed in correspondence with the depression position of an accelerator pedal,
Regarding the operation from the start of depression of the accelerator pedal, the continuously variable transmission mechanism (1) changes continuously from the stop speed to the maximum vehicle speed (F2), and the engine control range changes from the idling to the maximum torque ( F3) are provided separately, and the engine control range (F3) is set to the same range as the continuously variable transmission control range (F2).

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