JP2009186003A - Work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a work vehicle capable of suppressing the wear of a clutch by inching, and improving fuel cost. <P>SOLUTION: This work vehicle includes an engine, a travel mechanism, a clutch, an inching operation member, and a control part. The travel mechanism is configured to cause the vehicle to travel. The clutch is configured to transmit drive force from the engine to the travel mechanism. The inching operation member is configured to be operated to create slippage in the clutch to reduce vehicle speed. The control part is configured to calculate load (q) of the clutch during inching, and to reduce a rotational speed of the engine when the load (q) of the clutch exceeds a predetermined threshold α. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a work vehicle, and more particularly to a work vehicle having an inching function that causes slipping of a clutch to reduce the vehicle speed.

Some work vehicles have an inching function for reducing the vehicle speed by causing the clutch to slip. By using this inching function, the vehicle speed can be reduced while maintaining the engine speed at a certain level or higher. For example, a motor grader may travel while leveling with a blade. In this case, the operator can adjust the vehicle speed while suppressing a decrease in the driving force of the blade by operating the inching operation member to cause the clutch to slip.
JP 2000-337489 A

  However, in the work vehicle as described above, when the inching operation time becomes long, the amount of heat generated by the clutch increases and the wear of the clutch increases. During the inching operation, most of the output of the engine is not transmitted to the traveling device but is dissipated as heat, so that the engine output is wasted and the fuel consumption is reduced.

  An object of the present invention is to provide a work vehicle that can suppress clutch wear due to inching and improve fuel efficiency.

  A work vehicle according to a first aspect of the present invention includes an engine, a traveling mechanism, a clutch, an inching operation member, and a control unit. The traveling mechanism is a mechanism for causing the vehicle to travel. The clutch transmits the driving force from the engine to the traveling mechanism. The inching operation member is a member operated to reduce the vehicle speed by causing the clutch to slip. The control unit calculates the load of the clutch during inching, and reduces the engine speed when the clutch load exceeds a predetermined threshold.

  In this work vehicle, the operator operates the inching member to cause slipping of the clutch, thereby adjusting the vehicle speed. In addition, the control unit calculates the clutch load, and when this load exceeds a predetermined threshold value, the engine speed is reduced, so that excessive slipping of the clutch during inching as described above is suppressed. Can do. Thereby, wear of the clutch can be suppressed and the clutch can be protected. Moreover, since useless slipping of the clutch can be suppressed, fuel efficiency can be improved.

  A work vehicle according to a second aspect of the present invention is the work vehicle of the first aspect, wherein the control unit calculates a load of the clutch based on the surface pressure of the clutch and the slipping speed of the clutch.

  In this work vehicle, the clutch load can be easily calculated from the surface pressure of the clutch and the slipping speed of the clutch.

  A work vehicle according to a third aspect of the present invention includes an engine, a travel mechanism, a clutch, an inching operation member, and a control unit. The traveling mechanism is a mechanism for causing the vehicle to travel. The clutch transmits the driving force from the engine to the traveling mechanism. The inching operation member is a member operated to reduce the vehicle speed by causing the clutch to slip. The control unit calculates the temperature of the clutch during inching, and reduces the engine speed when the clutch temperature exceeds a predetermined threshold.

  In this work vehicle, the operator operates the inching member to cause slipping of the clutch, thereby adjusting the vehicle speed. In addition, the control unit calculates the temperature of the clutch, and when the clutch temperature exceeds a predetermined threshold value, the engine speed is reduced. Therefore, excessive slipping of the clutch during inching as described above is caused. Can be suppressed. Thereby, wear of the clutch can be suppressed and the clutch can be protected. Moreover, since useless slipping of the clutch can be suppressed, fuel efficiency can be improved.

  In the work vehicle according to the present invention, excessive slipping of the clutch during inching can be suppressed. Thereby, wear of the clutch can be suppressed and the clutch can be protected. Moreover, since useless slipping of the clutch can be suppressed, fuel efficiency can be improved.

<Configuration>
〔overall structure〕
An external perspective view and a side view of a work vehicle 1 according to an embodiment of the present invention are shown in FIGS. The work vehicle 1 is a motor grader and includes six traveling wheels including a pair of left and right front wheels 11 and two rear wheels 12 on each side. The work vehicle 1 can perform leveling work, snow removal work, light cutting, material mixing, and the like with a blade 42 provided between the front wheel 11 and the rear wheel 12. In FIGS. 1 and 2, only the one located on the left side of the four rear wheels 12 is illustrated.

  As shown in FIGS. 1 and 2, the work vehicle 1 includes a frame 2, a cab 3, and a work machine 4. As shown in FIG. 3, the work vehicle 1 includes an engine 5, a power transmission mechanism 6, a traveling mechanism 9, a hydraulic drive mechanism 7, an operation unit 10, a control unit 8, and the like.

[Frame 2 and cab 3]
As shown in FIGS. 1 and 2, the frame 2 includes a rear frame 21 and a front frame 22.

  The rear frame 21 accommodates the engine 5, the power transmission mechanism 6, the hydraulic drive mechanism 7 and the like shown in FIG. Further, the rear frame 21 is provided with the four rear wheels 12 described above, and the vehicle can travel when the rear wheels 12 are rotationally driven by the driving force from the engine 5.

  The front frame 22 is attached in front of the rear frame 21, and the front wheel 11 described above is attached to the front end portion thereof.

  The cab 3 is placed on the rear frame 21, and operation parts such as a handle, a shift lever, an operation lever of the work machine 4, a brake, an accelerator pedal 14, and an inching pedal 13 are inside (see FIG. 3). Is provided. The cab 3 may be placed on the front frame 22.

[Working machine 4]
The work machine 4 includes a draw bar 40, a circle 41, a blade 42, a hydraulic motor 49, various hydraulic cylinders 44 to 48, and the like.

  The front end portion of the draw bar 40 is swingably attached to the front end portion of the front frame 22, and the rear end portion of the draw bar 40 moves up and down by the synchronized expansion and contraction of the pair of lift cylinders 44 and 45. Further, the draw bar 40 tilts in the vertical direction by different expansion and contraction of the lift cylinders 44 and 45. Further, the draw bar 40 swings up and down around an axis along the vehicle traveling direction by expansion and contraction of the draw bar shift cylinder 46.

  The circle 41 is rotatably attached to the rear end portion of the draw bar 40. The circle 41 is driven by a hydraulic motor 49 (see FIG. 1), and rotates clockwise or counterclockwise with respect to the draw bar 40 as viewed from above the vehicle.

  The blade 42 is supported so as to be slidable in the lateral direction with respect to the circle 41 and swingable up and down around an axis parallel to the lateral direction. Here, the lateral direction means the left-right direction with respect to the traveling direction of the vehicle. The blade 42 can be moved laterally with respect to the circle 41 by a blade shift cylinder 47 supported by the circle 41. The blade 42 can be swung around an axis parallel to the circle 41 with the tilt cylinder 48 (see FIG. 2) supported by the circle 41 to change the direction in the vertical direction. . As described above, the blade 42 can move up and down with respect to the vehicle, change the inclination with respect to the traveling direction, change the inclination with respect to the lateral direction, rotate, and shift in the left-right direction via the draw bar 40 and the circle 41.

  The hydraulic motor 49 can rotate the circle 41 by being driven by pressure oil supplied from a first hydraulic pump 71 described later.

  The various hydraulic cylinders 44 to 48 are cylinders driven by the hydraulic pressure supplied from the first hydraulic pump 71. As described above, the pair of lift cylinders 44 and 45, the drawbar shift cylinder 46, the blade shift cylinder 47, There is a tilt cylinder 48 or the like. The pair of lift cylinders 44 and 45 are provided to be separated from each other on the left and right sides with the front frame 22 interposed therebetween. The lift cylinders 44 and 45 are disposed substantially along the vertical direction, and are attached to the front frame 22 and the draw bar 40. The lift cylinders 44 and 45 expand and contract to move the rear end of the draw bar 40 up and down, thereby moving the blade 42 up and down. The drawbar shift cylinder 46 is disposed so as to be inclined with respect to the vertical direction, and is attached to the side ends of the front frame 22 and the drawbar 40. The drawbar shift cylinder 46 can change the inclination angle of the drawbar 40 with respect to the lateral direction by expanding and contracting, and thereby the inclination angle of the blade 42 can be changed. The blade shift cylinder 47 is disposed along the longitudinal direction of the blade 42 and is attached to the circle 41 and the blade 42. The blade shift cylinder 47 can change the position in the longitudinal direction of the blade 42 by expanding and contracting. The tilt cylinder 48 is attached to the circle 41 and the blade 42. By extending and contracting, the tilt cylinder 48 can swing the blade 42 up and down around an axis along the lateral direction. The inclination angle with respect to can be changed.

[Engine 5]
As shown in FIG. 3, a fuel injection pump 15 is attached to the engine 5, and fuel is supplied from the fuel injection pump 15 to the engine 5. The supply amount is controlled by a command signal output from the control unit 8 described later to the electronic governor 16. The rotational speed of the engine 5 is detected by an engine rotational speed sensor 81 and sent to the control unit 8 as a detection signal. The control unit 8 can control the number of revolutions of the engine 5 by sending a command signal to the electronic governor 16 to control the amount of fuel supplied to the engine 5.

[Power transmission mechanism 6]
The power transmission mechanism 6 is a mechanism for transmitting the driving force from the engine 5 to the rear wheels 12 and includes a torque converter 62 and a transmission 60.

  The torque converter 62 is connected to the output side of the engine 5. The torque converter 62 is provided with a lockup clutch 70 that directly connects the input shaft and the output shaft of the torque converter 62. The lockup clutch 70 is a hydraulic clutch driven by hydraulic pressure supplied from a second hydraulic pump 72 described later. The lock-up clutch 70 is switched between the engaged state and the released state by operating the changeover switch included in the operation unit 10 described above. When the changeover switch is operated to the lock-up state by the operator, the control unit 8 transmits a command signal to the lock-up clutch control valve 58 to supply hydraulic pressure to the lock-up clutch 70 so that the lock-up clutch 70 The engaged state is established. When the lockup clutch 70 is engaged, the driving force from the engine 5 is transmitted without passing through the torque converter 62. When the lock-up clutch 70 is released, the driving force from the engine 5 is transmitted via the torque converter 62.

  The transmission 60 includes various clutches 63 to 69 and a plurality of transmission gears (not shown).

  The various clutches 63 to 69 are hydraulic clutches driven by hydraulic pressure supplied from a second hydraulic pump 72 described later, and include an FL clutch 63, an FH clutch 64, an R clutch 65, a first clutch 66, a second clutch 67, There is a 3rd clutch 68 and a 4th clutch 69. The FL clutch 63 and the FH clutch 64 are engaged when the vehicle moves forward. The R clutch 65 is engaged when the vehicle moves backward. The 1st clutch 66, the 2nd clutch 67, the 3rd clutch 68, and the 4th clutch 69 are engaged when transmitting the driving force to the corresponding transmission gears. In this transmission 60, at the time of forward movement, the 1st to 8th speed stages can be selected by a combination of either the FL clutch 63 or the FH clutch 64 and any of the first clutch 66 to the 4th clutch 69. Further, at the time of reverse travel, the speed stage of 1st to 4th speed can be selected by a combination of the R clutch 65 and any of the 1st clutch 66 to the 4th clutch 69.

  The input rotational speed to the FL clutch 63 and the FH clutch 64 is detected by the input rotational speed sensor 82 and sent to the control unit 8 as a detection signal. The output rotation speed from the FL clutch 63 and the FH clutch 64 is detected by the output rotation speed sensor 83 and sent to the control unit 8 as a detection signal.

[Running mechanism 9]
The traveling mechanism 9 is a mechanism for causing the vehicle to travel using the driving force from the engine 5. The traveling mechanism 9 is transmitted with the driving force from the engine 5 through the power transmission mechanism 6. The traveling mechanism 9 has a final reduction gear, a tandem device 61, and a rear wheel 12 (not shown). The driving force output from the transmission 60 is transmitted to the rear wheel 12 via the final reduction gear and the tandem device 61, and the vehicle travels by driving the rear wheel 12 to rotate.

[Hydraulic drive mechanism 7]
The hydraulic drive mechanism 7 is a mechanism for generating hydraulic pressure by the driving force from the engine 5 and driving the various clutches 63 to 69, the hydraulic motor 49, and the various cylinders 44 to 48 described above by the hydraulic pressure. The hydraulic drive mechanism 7 includes a first hydraulic pump 71, a second hydraulic pump 72, and various hydraulic control valves 73 to 78, 51 to 57.

  The first hydraulic pump 71 is driven by the driving force from the engine 5 and generates hydraulic pressure supplied to the various cylinders 44 to 48 and the hydraulic motor 49. The first hydraulic pump 71 is a variable displacement hydraulic pump that can change the displacement of the pressure oil discharged by changing the tilt angle of the swash plate by the pump displacement control cylinder 71a.

  The second hydraulic pump 72 is driven by the driving force from the engine 5 and generates hydraulic pressure supplied to the various clutches 63 to 69.

  The various hydraulic control valves 73 to 78 and 51 to 57 are electromagnetic proportional control valves capable of adjusting the hydraulic pressure by being electrically controlled by the control unit 8, and the first to fifth cylinder control valves 73. -77, hydraulic motor control valve 78, first to seventh clutch control valves 51-57, and the like.

  The first to fifth cylinder control valves 73 to 77 adjust the hydraulic pressure supplied to the various cylinders 44 to 48 described above. The hydraulic pressure supplied to the various cylinders 44 to 48 is detected by a hydraulic sensor (not shown) and sent to the control unit 8 as a detection signal.

  The hydraulic motor control valve 78 adjusts the hydraulic pressure supplied to the hydraulic motor 49 described above.

  The first to seventh clutch control valves 51 to 57 adjust the hydraulic pressure supplied to the various clutches 63 to 69 described above. Specifically, the first clutch control valve 51 adjusts the hydraulic pressure supplied to the FL clutch 63. The second clutch control valve 52 adjusts the hydraulic pressure supplied to the FH clutch 64. The third clutch control valve 53 adjusts the hydraulic pressure supplied to the R clutch 65. The fourth clutch control valve 54 adjusts the hydraulic pressure supplied to the first clutch 66. The fifth clutch control valve 55 adjusts the hydraulic pressure supplied to the second clutch 67. The sixth clutch control valve 56 adjusts the hydraulic pressure supplied to the 3rd clutch 68. The seventh clutch control valve 57 adjusts the hydraulic pressure supplied to the 4th clutch 69.

  Further, the hydraulic pressure supplied to the various clutches 63 to 69 is detected by a hydraulic pressure sensor and sent to the control unit 8 as a detection signal. In FIG. 3, only a hydraulic sensor 84 for detecting the hydraulic pressure supplied to the FL clutch 63 and a hydraulic sensor 85 for detecting the hydraulic pressure supplied to the FH clutch 64 are shown, and other hydraulic sensors are omitted. Yes.

[Operation unit 10]
The operation unit 10 is a part that is operated by an operator in order to control the traveling of the work vehicle 1 and the work machine 4. The operation unit 10 includes operation members such as an accelerator pedal 14 and an inching pedal 13. The accelerator pedal 14 is an operation member for setting the engine speed to a desired speed. The inching pedal 13 is an operation member that is operated to cause the FL clutch 63 or the FH clutch 64 to slip to reduce the vehicle speed. When each operation member of the operation unit 10 is operated, an operation signal corresponding to the operation amount is sent to the control unit 8.

[Control unit 8]
The control unit 8 controls the first to fifth cylinder control valves 73 to 77 and the hydraulic motor control valve 78 based on operation signals from the operation unit 10, detection signals from various sensors, and the like. 4 can be controlled. For example, the control unit 8 transmits a command signal to the first cylinder control valve 73 and the second cylinder control valve 74 to control the hydraulic pressure supplied to the lift cylinders 44 and 45, thereby moving the blade 42 in the vertical direction. Can be moved.

  Moreover, the control part 8 is suitable for the state of the vehicle by controlling the 1st-7th clutch control valves 51-57 based on the operation signal from the operation part 10, the detection signal from various sensors, etc. Shift control can be performed. For example, the control unit 8 transmits a command signal to the first clutch control valve 51, supplies hydraulic pressure to the FL clutch 63, and transmits a command signal to the seventh clutch control valve 57, to the 4th clutch 69. Supply hydraulic pressure. As a result, the FL clutch 63 and the 4th clutch 69 are engaged, and the seventh speed stage can be selected. Further, a command signal is transmitted to the second clutch control valve 52 to supply hydraulic pressure to the FH clutch 64, and a command signal is transmitted to the fourth clutch control valve 54 to supply hydraulic pressure to the first clutch 66. As a result, the FH clutch 64 and the first clutch 66 are engaged, and the second speed stage can be selected.

  The control unit 8 determines the fuel supply amount to the engine 5 based on the operation signal from the accelerator pedal 14 and the engine speed detected by the engine speed sensor 81. Then, the control unit 8 transmits a command signal corresponding to the determined supply amount to the electronic governor. Thereby, the fuel injection amount from the fuel injection pump is adjusted to an amount commensurate with the operation amount of the accelerator pedal 14 (hereinafter referred to as “accelerator operation amount”), and the engine speed is controlled. Thereby, the operator can control the output of the work machine 4 and the speed of the vehicle.

  Further, when the inching pedal 13 is operated, the control unit 8 adjusts the command signal to the first clutch control valve 51 or the second clutch control valve 52 based on the operation signal from the inching pedal 13. As a result, the hydraulic pressure supplied to the FL clutch 63 or the FH clutch 64 is reduced. That is, by reducing the surface pressure of the clutch in the engaged state of the FL clutch 63 or the FH clutch 64, the clutch is caused to slip. Thereby, the driving force transmitted from the power transmission mechanism 6 to the traveling mechanism 9 is reduced, and the vehicle speed is reduced. Therefore, the operator can adjust the vehicle speed by operating the inching pedal 13 while maintaining the output of the work implement 4 while suppressing the decrease in the engine speed. Here, in this work vehicle 1, clutch protection control shown in FIG. 4 is performed in order to prevent excessive clutch slippage. Hereinafter, clutch protection control will be described based on the flow shown in FIG.

  First, in the first step S1, it is determined whether or not slippage due to inching has occurred in the clutch. Here, based on the operation signal from the inching pedal 13 and the detection results of the input rotation speed sensor 82 and the output rotation speed sensor 83, it is determined whether or not slippage has occurred in the clutch.

  If slippage due to inching occurs in the clutch in the first step S1, the process proceeds to the second step S2. In the second step S2, the clutch load (q) is calculated. Here, the load of the clutch is proportional to the product of the surface pressure of the clutch in the engaged state and the slipping speed of the clutch, and is thus calculated from the surface pressure of the clutch and the slipping speed of the clutch. The surface pressure of the clutch can be calculated from the hydraulic pressure supplied to the FL clutch 63 or the FH clutch 64, the area of the clutch disk, and the like. More specifically, the clutch pressing force can be calculated by multiplying the area of the piston part that operates the clutch by the hydraulic pressure, and the clutch pressing force can be calculated by dividing the clutch pressing force by the area of the contact portion of the clutch disk. The pressure can be calculated. Note that the hydraulic pressure supplied to the FL clutch 63 or the FH clutch 64 is obtained from the detection results by the hydraulic sensors 84 and 85 described above. The slipping speed of the clutch is the difference between the input rotational speed to the FL clutch 63 or the FH clutch 64 and the output rotational speed from the FL clutch 63 or the FH clutch 64. The input rotational speed sensor 82 and the output rotational speed sensor 83 described above It can calculate from the detection result by.

  Then, in the third step S3, it is determined whether or not the clutch load (q) exceeds a predetermined threshold value (α).

  If it is determined in the third step S3 that the clutch load exceeds a predetermined threshold, the process proceeds to a fourth step S4. In the fourth step S4, the amount of fuel supplied to the engine 4 is reduced, whereby the engine speed is reduced. The amount of reduction in the fuel supply amount (hereinafter simply referred to as “fuel reduction amount”) varies so as to increase in accordance with an increase in the clutch load, as shown in FIG. Thereby, as shown in FIG. 6, it is suppressed that the load of a clutch increases excessively. In FIG. 6, a change in clutch load when the clutch protection control is not performed is indicated by a two-dot chain line. The change in the fuel reduction amount shown in FIG. 5 is calculated in advance as a value necessary for protecting the clutch, and is stored in the control unit 8 as a graph or a map.

  If it is determined in the first step S1 that slippage due to inching has not occurred in the clutch, and if it is determined in the third step S3 that the clutch load does not exceed a predetermined threshold value, 5 Proceed to step S5. In the fifth step S5, it is determined whether or not the fuel supply amount is an amount commensurate with the accelerator operation amount.

  In the fifth step S5, when it is determined that the fuel supply amount is not an amount commensurate with the accelerator operation amount, the process proceeds to a sixth step S6. In the sixth step S6, the fuel supply amount is increased to an amount commensurate with the accelerator operation amount. For this reason, when the load of the clutch becomes smaller than the threshold value, the reduction of the fuel supply amount is stopped, and the fuel supply amount is set to an amount corresponding to the accelerator operation amount. As a result, the engine speed, which has been reduced for protection of the clutch, can be returned to the original speed.

  In the fifth step S5, when it is determined that the fuel supply amount is an amount commensurate with the accelerator operation amount, the process returns to the first step S1.

<Features>
In this work vehicle 1, it is possible to suppress excessive clutch slipping during inching. Thereby, increase of the load of a clutch can be suppressed and a clutch can be protected.

  Further, in this work vehicle 1, since excessive clutch slip is suppressed, fuel consumption can be improved. That is, during inching, a part of the engine output is discarded as heat due to slipping of the clutch, and in a conventional work vehicle, the engine output becomes excessive during inching, so that more parts are discarded as heat. ing. Therefore, in this work vehicle 1, by reducing the engine speed by the wasteful engine output, fuel efficiency can be improved without excessively reducing the vehicle speed.

<Other embodiments>
(A)
In the above embodiment, the control unit 8 reduces the engine speed when the clutch load exceeds a predetermined threshold, but when the clutch temperature exceeds the predetermined threshold, the engine speed is decreased. May be reduced. Since it is difficult to directly measure the temperature of the clutch, it can be calculated, for example, by the following mathematical formula.

ここで、Ｔ：クラッチの温度、Ｔ_０：クラッチの初期温度、μ：クラッチディスクの動摩擦係数、Ｐ：クラッチディスクのみかけ面圧、Ｖ：クラッチディスクの平均径周速、αｍ：平均熱伝達率、ｃ：クラッチディスクの比熱、γ：クラッチディスクの比重、Ｖ_０：クラッチディスクの体積、ｔ：時間、である。なお、「クラッチディスクのみかけ面圧」とは、クラッチディスクの表面に形成された溝を含めたクラッチディスクの面積を考慮した面圧を意味する。「クラッチディスクの平均径周速」とは、クラッチディスクの外径と内径との平均径における周速を意味する。また、「平均熱伝達率」とは、クラッチディスクから圧油への平均熱伝達率を意味する。

Here, T: temperature of clutch, T ₀ : initial temperature of clutch, μ: coefficient of dynamic friction of clutch disk, P: apparent surface pressure of clutch disk, V: average peripheral speed of clutch disk, αm: average heat transfer coefficient C: specific heat of clutch disk, γ: specific gravity of clutch disk, V ₀ : volume of clutch disk, t: time. The “appearance surface pressure of the clutch disk” means a surface pressure in consideration of the area of the clutch disk including the groove formed on the surface of the clutch disk. The “average peripheral speed of the clutch disk” means a peripheral speed at an average diameter of the outer diameter and the inner diameter of the clutch disk. The “average heat transfer coefficient” means the average heat transfer coefficient from the clutch disk to the pressure oil.

(B)
In the above embodiment, the surface pressure of the clutch is obtained from the oil pressure detected by the oil pressure sensors 84 and 85, but a command signal sent from the control unit 8 to the first clutch control valve 51 or the second clutch control valve 52. May be required. Further, it may be obtained from an operation signal from the inching pedal 13.

(C)
In the above embodiment, a motor grader is mentioned as the work vehicle, but the present invention may be applied to other work vehicles such as a bulldozer, a wheel loader, and a forklift.

(D)
In the above embodiment, the inching operation is performed by the inching pedal 13, but other operation members such as a lever are not limited to the pedal, and may be used as the inching operation member.

(E)
In the above embodiment, inching is performed by reducing the hydraulic pressure supplied to the FL clutch 63 or the FH clutch 64, but inching is performed by reducing the hydraulic pressure supplied to the other clutches. May be.

  INDUSTRIAL APPLICABILITY The present invention has an effect of suppressing the wear of a clutch due to inching and is useful as a work vehicle.

The external appearance perspective view of a working vehicle. The side view of a work vehicle. The block diagram which shows the structure of a working vehicle. The flowchart of clutch protection control. The graph which shows the relationship between fuel reduction amount and clutch load. The graph which shows the change of the clutch load when clutch protection control is performed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Work vehicle 5 Engine 8 Control part 9 Traveling mechanism 13 Inching pedal (inching operation member)
16 Electronic governor 51 First clutch control valve 52 Second clutch control valve 63 FL clutch (clutch)
64 FH clutch (clutch)
82 Input speed sensor 83 Output speed sensor 84, 85 Hydraulic sensor

Claims (3)

Engine,
A traveling mechanism for traveling the vehicle;
A clutch for transmitting driving force from the engine to the traveling mechanism;
An inching operation member operated to reduce the vehicle speed by causing the clutch to slip; and
A control unit that calculates a load of the clutch during inching and reduces the engine speed when the load of the clutch exceeds a predetermined threshold;
Work vehicle equipped with. The control unit calculates a load of the clutch based on a surface pressure of the clutch and a slipping speed of the clutch;
The work vehicle according to claim 1.

Engine,
A traveling mechanism for traveling the vehicle;
A clutch for transmitting driving force from the engine to the traveling mechanism;
An inching operation member operated to reduce the vehicle speed by causing the clutch to slip; and
Calculating the temperature of the clutch during inching, and when the temperature of the clutch exceeds a predetermined threshold, a control unit for reducing the rotational speed of the engine;
Work vehicle equipped with.

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