JP2005271919A - Working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To rationally constitute a working vehicle with good linear advancement property at braking not performing rapid braking while increasing vehicle body brake force by forming the four-wheel driving state in the front wheel speed-increase state by turning ON a friction clutch at the front wheel speed-increase side when braking in the two-wheel driving state. <P>SOLUTION: The working vehicle is provided with a front wheel transmission A capable of setting to a neutral position for shutting off power to the front wheel 1, a four-wheel driving position for transmitting driving force equal to circumferential speed of a rear wheel 2 to the front wheel 1; and a speed increase position for transmitting driving force of higher speed than circumferential speed of the rear wheel 2 to the front wheel 1. The front wheel transmission A is constituted so as to be provided with friction clutches Ce, Cf. It is provided with a forcing control means for also setting the front wheel 1 to the restriction state by turning ON the friction clutch Cf at the front wheel speed increase side at braking of the rear wheel 2 by operation of a brake pedal 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a four-wheel drive position for setting the peripheral speed of the front wheel to a speed equal to the peripheral speed of the rear wheel, an acceleration position for increasing the peripheral speed of the front wheel from the peripheral speed of the rear wheel, Work including a front wheel transmission that can be switched to a neutral position where power is cut off, and front wheel transmission that switches the front wheel transmission from the four-wheel drive position to the acceleration position in conjunction with the steering operation of the front wheels More specifically, the present invention relates to a technique for setting a front wheel to a transmission state when there is an operation of braking the rear wheel during traveling in a two-wheel drive state.

  There is a work vehicle configured as described above in Japanese Patent Laid-Open No. 10-217790, and in this conventional example, when the left and right brake pedals are depressed when traveling in a two-wheel drive state, In addition, it is described that the standard four-wheel drive state is set to improve the braking performance (paragraph number [0027]).

  In the work vehicle mentioned in the prior art, when the shift member of the front wheel transmission is operated to the speed increasing side, the friction clutch reaches the transmission state, and the front wheel transmits the power increased from the rear wheel to the front wheel. When the shift member is operated to the standard side, power at the same speed as the rear wheel is transmitted to the front wheel via the occlusal clutch (standard four-wheel drive state), and the shift member is set to the neutral position. The power to the wheels is cut off (two-wheel drive state). However, in this conventional work vehicle, when a rear wheel is braked in a two-wheel drive state, a structure in which an occlusal clutch is engaged and operated in conjunction with this operation is set to a standard four-wheel drive state. Therefore, there is room for improvement in terms of durability as well as generating abnormal noise.

  An object of the present invention is to rationally configure a quiet and highly durable work vehicle without impairing the effectiveness of setting the four-wheel drive state when braking in the two-wheel drive state to improve the braking performance. .

  The first feature of the present invention (Claim 1) is that the front wheel peripheral speed is set equal to the rear wheel peripheral speed, and the front wheel peripheral speed is increased from the rear wheel peripheral speed. A front wheel transmission that can be switched between a speed increasing position for speeding up and a neutral position that cuts off power to the front wheels, and the front wheel transmission from the four-wheel drive position to the speed increasing position in conjunction with the steering operation of the front wheels. In the work vehicle including the front wheel transmission means for switching to the front wheel transmission device, the front wheel transmission device includes a friction clutch that reaches the on-state at the acceleration position or the four-wheel drive position and transmits power to the front wheels. When the operation for braking the rear wheel is performed in a state where the front wheel transmission is in the neutral position, the operation is provided with a forcible control means for engaging and operating the clutch, The effect is as follows.

  A second feature of the present invention (Claim 2) is that, in Claim 1, the operation mode is set so that the forcible control means performs the clutch engagement operation linked to the braking operation of the rear wheel for a set time. The operation and effect are as follows.

  A third feature of the present invention (Claim 3) is that, in Claim 2, the operation mode of the forcible control means is set so that the set time is extended as the traveling speed of the vehicle body increases. The operation and effect are as follows.

  According to a fourth feature of the present invention (Claim 4), in any one of Claims 1 to 3, the forcible control means is operated in a state where the traveling speed of the vehicle body exceeds a preset speed. The operation and effect of the clutch are configured to allow the clutch engagement operation linked to the wheel braking operation.

  According to a fifth feature of the present invention (Claim 5), in any one of Claims 1 to 4, the forcible control means is in a state where the steering angle of the front wheel is equal to or less than a preset angle. The clutch is configured to permit the clutch engagement operation linked to the braking operation of the rear wheel, and its operation and effect are as follows.

  According to a sixth aspect of the present invention (Claim 6), in any one of Claims 1 to 5, a hydraulic cylinder mechanism for engaging and operating the clutch is provided, and the clutch is controlled by the forced control means. In this case, there is an adjusting means for reducing the impact by adjusting the pressurizing characteristic of the hydraulic oil supplied to the cylinder mechanism, and its operation and effect are as follows.

  A seventh feature of the present invention (Claim 7) is that, in Claim 6, the processing mode is set so that the adjusting means changes the pressure rising characteristic of the hydraulic oil supplied to the cylinder mechanism based on the traveling speed of the vehicle body. The operation and effect are as follows.

  An eighth feature of the present invention (Claim 8) is the pair of brakes according to any one of Claims 1 to 7, wherein the rear wheels are provided as a pair of left and right wheels, and the left and right rear wheels are independently braked. The forcible control means is configured to include a pedal and a connecting member that integrally operates the left and right brake pedals and to allow the clutch to be engaged when it is determined that the connecting member is in a connected state. The operation and effect are as follows.

  According to a ninth feature (claim 9) of the present invention, in any one of the claims 1-8, the vehicle is provided with a speed reduction means for reducing the traveling speed when the clutch is engaged with the rear wheel braking operation. The operation and effect are as follows.

  A tenth feature of the present invention (Claim 10) is the selection mechanism according to any one of Claims 1 to 9, wherein the selection mechanism is configured to select a state in which a clutch engagement operation by the forcible control means is permitted and a state in which a clutch is to be blocked. The function and effect are as follows.

[Action]

  According to the first feature, when the front wheel is steered with the front wheel transmission set to the four-wheel drive position, the front wheel transmission means switches the front wheel transmission to the speed increasing position to reduce the radius of the front wheel. When the vehicle is allowed to turn and the rear wheel is braked when traveling with the front wheel transmission in the neutral position (two-wheel drive state), the forced control means engages the friction clutch. Thus, the front wheels and the rear wheels are set to the transmission state, and the front and rear wheels are set to the restrained state to improve the braking performance. When the front wheels are set to the transmission state in this way, the friction type clutch is engaged and operated, so that the switching to the transmission state is smooth.

  According to the second feature, the front and rear wheels are restrained only at the initial stage of braking where a strong braking force is required, and the strong braking force is applied. Durability is improved.

  According to the third feature, the front and rear wheels are restrained only in the initial stage of braking where a strong braking force is required, and a strong braking force is applied. In addition, the durability of the clutch is improved, and the restraint time is reduced by the vehicle speed. As a result of the extension, the higher the speed, the better the speed can be reduced even at high speeds.

  According to the fourth feature, when the braking operation is performed in a state exceeding the set speed, the front and rear wheels are restrained to strongly decelerate with a strong braking force, and the braking operation is performed without exceeding the set speed. In this case, only the rear wheels are constrained and the vehicle is smoothly decelerated with a weak braking force.

  According to the fifth feature, when the vehicle body is turned by a large steering operation, the posture of the vehicle body is stabilized by avoiding the action of a strong braking force.

  According to the sixth feature, when the clutch mechanism is engaged and operated in conjunction with the braking operation, the pressure adjusting means adjusts the pressure rising characteristic of the hydraulic oil, thereby reducing the impact during the engagement operation. It will be possible to eliminate the impact during the operation.

  According to the seventh feature, by adjusting the step-up characteristic of the pressure adjusting means based on the traveling speed, the braking force is eliminated during the high-speed driving and the low-speed driving while eliminating the shock during the clutch engagement operation. The braking force can be applied satisfactorily.

  According to the eighth feature, the clutch is engaged and operated only when there is an operation of braking the rear wheel while the connecting member is connected. For example, in a state where the connection of the connecting member is released. When the rear wheel inside the turn is braked for the purpose of turning with a small radius, the disadvantage that power is transmitted to the front wheel is solved.

  According to the ninth feature, the speed reducing means reduces the traveling speed in conjunction with the clutch engagement operation, so that the traveling speed is reduced by the braking and deceleration by the front and rear wheels even if the braking operation is lightly performed.

  According to the tenth feature, when the state allowing the clutch engagement operation is selected by the selection mechanism, a good braking state appears, and when the state preventing the clutch engagement operation is selected, only the rear wheels are selected. It is also possible to apply braking force lightly by braking.

〔The invention's effect〕
Therefore, a work vehicle in which the durability of the clutch is improved silently when the clutch is engaged without impairing the effectiveness of setting the four-wheel drive state during braking in the two-wheel drive state to improve the braking performance. Is reasonably constructed (claim 1). Further, a strong braking force is applied at a necessary timing without performing useless braking, and durability is improved (Claim 2), and strong at a necessary timing without performing useless braking regardless of the traveling speed. Applying braking force and improving durability (Claim 3), switching between braking of only the rear wheel and braking of the front and rear wheels based on the traveling speed (Claim 4), when turning the vehicle body When turning at a small radius, avoid the action of strong braking force to stabilize the posture of the vehicle body (Claim 5), and smoothly engage and operate the clutch during braking (Claim 6). The clutch smoothly enters and operates without falling (claim 7), and when the rear wheel inside the turn is braked to make a turn with a small radius, the front wheel is prevented from being braked to enable a smooth turn ( (8) Good deceleration in conjunction with braking operation It shall be to (claim 9), was the one that emerges only valid good braking state if necessary by the selection operation (claim 10).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, an engine 4 is mounted on a front portion of a vehicle body 3 having a front wheel 1 and a rear wheel 2, and power from the engine 4 is connected to the vehicle body via a main clutch housed in a main clutch housing 5. It is equipped with a transmission system that transmits to the transmission case 6 arranged at the rear, the steering handle 7 is arranged at the center of the vehicle body 3, and the driver's seat 8 is arranged at the middle position between the fenders of the left and right rear wheels 2 for agricultural use as a work vehicle Configure the tractor.

  As shown in FIGS. 1 and 3, a side brake 9 for independently braking the left and right rear wheels 2 is provided on the side surface of the transmission case 6, and a stepping operation is performed on the right side of the step in front of the driver seat 8. A pair of left and right brake pedals 10 for braking the left and right side brakes 9 are arranged, and the pair of left and right brake pedals 10 are connected by a connecting metal fitting 12 as a connecting member configured to freely change the posture around a support shaft 11. By doing so, it is configured to operate integrally. Note that a connection switch 13 for detecting that the connection fitting 12 is set at the connection position and a brake switch 14 for detecting that the brake pedal 10 is depressed are provided. On the left side of the step, a main clutch pedal 15 for disengaging the main clutch by a stepping operation is disposed. Further, the steering operation system of the front wheel 1 is provided with a potentiometer type steering sensor 16 for measuring the steering angle.

  Based on the operation of the speed change lever 17, the transmission case 6 operates a built-in hydraulic speed change mechanism without manually disengaging the main clutch, and changes the speed of the gear type speed change mechanism. A front wheel transmission A that transmits power to the front wheels 1 is provided on the lower surface of the transmission case 6, and the structure of the front wheel transmission A will be described below.

  As shown in FIG. 4, the power shifted in the transmission case 6 is transmitted to the rear wheel 2 via the transmission shaft 21 via the differential mechanism D, and the power from the transmission shaft 21 is idled and supported on the intermediate shaft 22. A transmission system is formed for transmission to the first gear 25 of the counter shaft 24 via the intermediate gear 23. Further, the standard transmission gear 27 and the first gear 25 of the counter shaft 24 are engaged with the output shaft 26 provided in a parallel posture with the counter shaft 24, and the second gear 28 of the counter shaft 24 and the output shaft are engaged. 26 is engaged with a high-speed transmission gear 29 that is idle-supported, and friction clutches Ce and Cf are integrally formed with the standard transmission gear 27 and the high-speed transmission gear 29, respectively, with respect to these intermediate positions. A shift member 30 that engages and operates the clutches Ce and Cf is externally fitted to the output shaft 26 so as to be slidable through a spline. The clutches Ce and Cf are collectively referred to as the clutch C.

  As shown in the figure, an intermediate transmission shaft 31 that transmits power to the front wheels 1 is connected to the front end of the output shaft 26, and the shift member 30 is set to the neutral position N so that power is transmitted to the output shaft 26. First, a two-wheel drive state in which the driving force is transmitted only to the rear wheel 2 appears, and the clutch Ce is engaged by setting this shift member to the standard position E on the standard transmission gear 27 side with respect to the neutral position N. Thus, a standard four-wheel drive state for transmitting power to the front wheel 1 at a peripheral speed equal to the peripheral speed of the rear wheel 2 appears, and the shift member 30 is located on the high-speed transmission gear 29 side with respect to the neutral position N. The four-wheel drive state (front wheel) in which the front wheel 1 transmitting the power that is higher than the peripheral speed of the rear wheel 2 to the front wheel 1 is increased by setting the clutch Cf to the forward speed position F. Acceleration state) appears.

  The front wheel transmission A is provided with a hydraulic cylinder B that slides the shift member 30 via a shifter 32. The hydraulic cylinder B includes a cylinder tube 35 in which a small inner diameter portion and a large inner diameter portion are integrally formed, and a piston rod 36 having a piston 36P fitted inside the small inner diameter portion is penetrated in the axial direction. A ring-shaped movable piston 37 that is slidably fitted to the piston rod 36 and fitted inside the large inner diameter portion is provided, and ports are formed at both ends and the center of the cylinder tube 35. The shifter 32 is connected to the piston rod 36.

  Solenoid valves V are provided for the three oil passages for supplying hydraulic oil from the hydraulic pump P to the respective ports. By selecting and driving these solenoid valves V, the shift member 30 is set to the neutral position N, It is configured so that it can be set to any one of the standard position E and the acceleration position F. Specifically, by supplying pressure oil to the ports at both ends, the movable piston 37 comes into pressure contact with the piston portion 36P in contact with the stepped portion of the cylinder tube 35 as shown in FIG. The shift member 30 can be set to the neutral position N, and as shown in FIG. 5, the pressure oil is supplied only to the port at the center position, so that the piston portion 36P moves to the right end portion in the same figure. The member 30 can be set at the standard position E. As shown in FIG. 6, the supply of pressure oil to the right port causes the piston portion 36P to move to the left end portion in the same figure, thereby increasing the shift member 30. It can be installed at the fast position F.

  As shown in FIG. 3, a control system is formed. In this control system, the control device 38 having a microprocessor is driven by the two-wheel drive of the rear wheel 2 and the four-wheel drive (standard) of the front and rear wheels. A signal from a mode switch 40 for selecting one of three modes of traveling and traveling in which the front wheel 1 is accelerated at the time of turning in the four-wheel driving state of the front and rear wheels, and the rear wheel in the two-wheel driving state A signal from the selection switch 39 as a selection mechanism for selecting a state in which the braking force is applied also to the front wheels 2 by operating the standard-side clutch Ce when the braking operation is performed on 1, a signal from the connection switch 13, From the signal from the brake switch 14, the signal from the vehicle speed sensor 41 that measures the traveling speed from the drive speed of the transmission system in the transmission case 6, and the shift lever sensor 42 that detects the set position of the shift lever 17. A signal system is formed so that a signal and a signal from the steering sensor 16 are input, and a signal system for the three electromagnetic valves V and the transmission motor 43 that forcibly operates the transmission lever 17 is formed. .

  And the control program of this control apparatus 38 is comprised like the flowchart of FIG. That is, when the four-wheel drive “four-wheel drive” mode is selected by the mode switch 40, the front wheel transmission A is set to the standard position E and maintained in the four-wheel drive state (# 101, # 102 steps). ). Further, when “acceleration” for increasing the speed of the front wheel 1 at the time of turning is selected by the mode switch 40, the front wheel transmission device A is set to the standard position E and the value detected by the shift lever sensor 42 is set. Only when the steering sensor 16 measures a steering angle exceeding a preset angle in a state where it is determined that the speed is less than a preset gear position ("low speed") based on the The front wheel 1 is accelerated at the acceleration position F, and this acceleration state is maintained until the steering amount is restored by the steering sensor 16 (steps # 101, # 103 to # 107). . Note that the front wheel speed change means J is configured in step # 106.

  When the two-wheel drive “two-wheel drive” mode is selected with the mode switch 40, the front wheel transmission A is set to the neutral position N to set the two-wheel drive state, and the selection switch 39 is used for braking. Sometimes, when the state in which the braking force is applied to the front wheel 1 is selected, the connection switch 13 detects that the connection fitting 12 is in the connection state, and the steering angle measured by the steering sensor 16 is the set angle. Only when it is less, the control shifts to control of the four-wheel braking routine (# 112 step), and these controls are continued until reset (# 101, # 108 to # 113). Step).

  As shown in the flowchart of FIG. 8, the four-wheel braking routine sets the pressure increase parameter and the ON time parameter based on the measurement result of the vehicle speed sensor 41, and when the brake switch 14 reaches the ON state, By controlling the opening degree, the pressure of the hydraulic oil supplied to the hydraulic cylinder B is increased according to the pressure increase parameter, while the front wheel transmission A is operated toward the standard position E, and the transmission motor 43 is driven. The shift stage is operated in the one-speed reduction direction, and the set time set by the ON time parameter elapses with reference to the timing at which the engagement control of the standard-side clutch Ce of the front wheel transmission device A is started as described above. When this set time has elapsed, the solenoid valve V is controlled to operate the hydraulic cylinder B to the neutral position N, and the clutch C It has become a performs processing to turn off the (# a~f step). Specifically, the pressure increase parameter sets the pressure increase curve of the supplied hydraulic oil to a steep angle so that the time required to reach the maximum pressure is shortened as the traveling speed of the vehicle body 3 is high, and conversely the traveling speed is low. The characteristic is set so as to smoothen the boosting curve of the hydraulic oil supplied as the pressure increases. The ON time parameter is set so that the higher the traveling speed of the vehicle body 3 is, the longer the time until the time is up and the braking force act for a long time. Note that a forcible control means K is configured to enter and operate the clutch C during the braking operation in step #c to set the front wheel 1 in a restrained state, and in step #a, the boosting characteristic of the hydraulic cylinder B based on the traveling speed of the vehicle body 3 Is configured, and a deceleration means M for reducing the traveling speed when the clutch C is engaged is configured by #d. In particular, in the present invention, when the rear wheel 2 is braked, when the front wheel transmission device A applies a braking force to the front wheel 1, the processing mode can be set so that the clutch Ce on the acceleration side is engaged and operated. is there.

  With this configuration, when the four-wheel drive “4WD” mode is selected by the mode switch 40, the front and rear wheels 1 and 2 are driven to enable work with a strong traction force. When “acceleration” for increasing the speed of the front wheel 1 at the time of turning by the mode switch 40 is selected, the front and rear wheels 1 and 2 are driven during straight running to enable work with strong traction force. When the front wheel 1 is steered to turn 3, the front wheel 1 is driven at an increased speed to enable turning with a small radius. In the state where the “drive” mode is selected and the state in which the braking force is applied to the front wheel 1 during braking is selected by the selection switch 39, the connecting bracket 12 is in the connected state and the steering measured by the steering sensor 16 is performed. Angle is set angle In the full state, only when the brake pedal 10 is used for braking, the standard-side clutch Ce is engaged and operated so that the braking force is applied smoothly to the front wheels 1, and the front wheels 1 and the rear wheels 2 are operated. These four wheels are strongly braked with a strong braking force in a braking state. Further, when the connecting bracket 12 is not in the connected state, the side brake 9 on the inner side of the turning is set to the braking state by blocking the clutch engagement operation of the front wheel transmission device A, and turning with a small radius is performed. The problem of transmitting power to the front wheel 1 is eliminated, and when the steering angle is large, the action of strong braking force is eliminated to avoid the phenomenon that the vehicle body 3 becomes unbalanced. When the braking force is applied to 1, the braking force is applied for a set time from the timing when the brake pedal 10 is depressed. The higher the speed, the longer the speed can be set, and the higher the traveling speed, the higher the speed of the hydraulic cylinder B. The higher the speed, the better the braking state without running out of braking. It has become a thing to be out.

Whole side view of agricultural tractor Plan view showing the outline of the transmission system, etc. Block diagram of control system The figure which shows the cross section of a front-wheel transmission and the cross section of a hydraulic cylinder Cross section of hydraulic cylinder with shifter set to standard position Cross section of hydraulic cylinder with shifter set to acceleration position Flow chart showing control operation Four-wheel braking routine flowchart

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front wheel 2 Rear wheel 3 Car body 39 Selection mechanism A Front wheel transmission C Clutch E Four-wheel drive position F Acceleration position N Neutral position J Front wheel transmission means K Forced control means L Adjustment means M Deceleration means

Claims (10)

The standard four-wheel drive position where the peripheral speed of the front wheel is set equal to the peripheral speed of the rear wheel, the front wheel acceleration position where the peripheral speed of the front wheel is increased from the peripheral speed of the rear wheel, and the power to the front wheel A front wheel transmission that can be switched to a neutral position to be shut off is provided, and the front wheel transmission is configured to include a clutch that reaches the engaged state at the front wheel acceleration position or the standard four-wheel drive position and transmits power to the front wheels. A work vehicle comprising front wheel transmission means for switching the front wheel transmission device from the standard four-wheel drive position to the front wheel acceleration position in conjunction with the steering operation of the front wheel,
The clutch includes a friction type multi-plate clutch, and when an operation of braking the rear wheel is performed in a state where the front wheel transmission is in a neutral position, the friction type clutch on the front wheel acceleration side is Work vehicle equipped with forced control means to enter and operate. 2. The work vehicle according to claim 1, wherein an operation mode is set so that the forcible control means performs the clutch engagement operation linked to the rear wheel braking operation for a set time. The work vehicle according to claim 2, wherein the operation mode of the forcible control means is set so that the set time is extended as the traveling speed of the vehicle body increases. The forced control means is configured to allow the clutch engagement operation linked to the braking operation of the rear wheel in a state where the traveling speed of the vehicle body exceeds a preset speed. The work vehicle according to claim 1. The said forced control means is comprised so that the engagement operation of the said clutch linked with the braking operation of a rear wheel may be permitted in the state in which the steering angle of the said front wheel is below a preset angle. The work vehicle according to any one of the above. A hydraulic cylinder mechanism for engaging and disengaging the clutch, and an adjusting means for reducing impact by adjusting a boosting characteristic of hydraulic oil supplied to the cylinder mechanism when the clutch is engaged and operated by the forced control means. The work vehicle according to any one of claims 1 to 5. The work vehicle according to claim 6, wherein a processing mode is set so that the adjusting means changes a pressure increasing characteristic of hydraulic oil supplied to the cylinder mechanism based on a traveling speed of a vehicle body. A pair of left and right rear wheels are provided, a pair of brake pedals for independently braking the left and right rear wheels are provided, a connecting member for operating the left and right brake pedals is provided, and the connecting member is in a connected state. The work vehicle according to any one of claims 1 to 7, wherein the forcible control means is configured to allow the clutch engaging operation when it is determined that the clutch is engaged. The work vehicle according to any one of claims 1 to 8, further comprising a speed reduction unit that reduces a traveling speed when the clutch is engaged with a rear wheel braking operation. The work vehicle according to any one of claims 1 to 9, further comprising a selection mechanism that performs selection between a state in which clutch engagement operation by the forcible control unit is permitted and a state in which it is blocked.

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