WO2010147150A1

WO2010147150A1 - Clutch control device for industrial vehicle

Info

Publication number: WO2010147150A1
Application number: PCT/JP2010/060215
Authority: WO
Inventors: 幸次兵藤; 裕喜中園; 正規吉川; 哲二田中
Original assignee: 日立建機株式会社
Priority date: 2009-06-17
Filing date: 2010-06-16
Publication date: 2010-12-23
Also published as: JP2011001986A

Abstract

A clutch control device for an industrial vehicle, provided with an approach determiner for determining whether or not the industrial vehicle (100) has approached an object, and also with a clutch controller (10) which, when the approach determiner determines that the industrial vehicle has approached the object, controls the engagement/disengagement of a forward clutch (18) so as to disengage the forward clutch (18).

Description

Clutch control device for industrial vehicles

The present invention relates to a clutch control device for an industrial vehicle such as a wheel loader.

In an industrial vehicle such as a wheel loader, for example, when loading earth and sand into a dump truck, etc., the vehicle is decelerated by stepping on the brake when approaching the dump truck, but the working machine device (bucket) is moved upward In order to raise it, the accelerator pedal is depressed to maintain the engine speed at a high speed. Therefore, for example, a clutch cutoff device that detects the operating state of the brake as the brake fluid pressure and releases the clutch for forward and reverse movement to shut off the transmission of the driving force when the detected brake fluid pressure exceeds a predetermined value. It is known (refer patent document 1).

Japanese Patent Publication 2001-263384

However, in the above-described clutch cutoff device, the release timing of the clutch for forward and reverse travel is determined only by the operating state of the brake. Therefore, depending on the working condition of the industrial vehicle and the degree of inclination of the road surface, the release timing of the forward and reverse clutch may not be appropriate, and the movement of the industrial vehicle may not be smooth before and after the clutch release operation.

According to the first aspect of the present invention, the clutch control device of the industrial vehicle approaches the approaching object by the approaching judgment device for judging whether the industrial vehicle approaches the approaching object and the approaching judgment device. If so, the clutch controller controls the engagement / release of the forward clutch so as to release the forward clutch.
According to a second aspect of the present invention, in the clutch control device for an industrial vehicle according to the first aspect,
The approach determiner determines that the speed ratio of the torque converter that transmits the power of the engine to the transmission is less than a predetermined speed ratio and the traveling speed of the industrial vehicle is less than a predetermined speed, and the braking force of the industrial vehicle is predetermined. It is preferable to determine that the industrial vehicle has approached the approaching object when a condition that is equal to or greater than the braking force is established.
According to a third aspect of the present invention, in the clutch control device for an industrial vehicle according to the first aspect,
The approach judging device is at least a predetermined braking force such that the traveling speed of the industrial vehicle is equal to or less than a predetermined speed against the traveling driving force of the industrial vehicle when approaching the approaching object. If it is determined that there is an object, it is preferable to determine that the industrial vehicle has approached the approaching object.
According to a fourth aspect of the present invention, in the clutch control device for an industrial vehicle according to the second aspect,
The apparatus further comprises selection means for causing the user to select whether the predetermined braking force is the first braking force or the second braking force larger than the first braking force, and the clutch control means is a selection means. When the predetermined braking force is selected to be the second braking force, it is difficult for the forward clutch to be released compared to when the selecting means selects the predetermined braking force to be the first braking force. Preferably, the engagement / release of the forward clutch is controlled.
According to a fifth aspect of the present invention, in the clutch control device for an industrial vehicle according to the third aspect,
The clutch controller further includes a selector for causing the user to select whether the predetermined braking force is the third braking force or the fourth braking force greater than the third braking force. When the selector selects the predetermined braking force as the fourth braking force, the forward clutch is engaged as compared to the case where the selector selects the predetermined braking force as the second braking force. It is preferable to control the engagement / release of the forward clutch so as to make it difficult to release.

According to the present invention, the movement of the industrial vehicle is smoothed.

It is a side view of a wheel loader which is an example of an industrial vehicle. FIG. 2 is a view showing a schematic configuration of a wheel loader 100. FIG. 2 is a view showing a schematic configuration of a transmission 3; It is a figure which shows the relationship between torque ratio e and a speed stage. It is a figure shown about V shape loading. It is a figure explaining the state of wheel loader 100 at the time of loading to a dump truck, such as earth and sand. It is the flowchart which showed the operation | movement of the clutch control processing in the wheel loader 100 of this Embodiment.

An embodiment of a clutch control device for an industrial vehicle according to the present invention will be described below with reference to FIGS. FIG. 1 is a side view of a wheel loader which is an example of an industrial vehicle to which the clutch control device according to the present embodiment is applied. The wheel loader 100 includes an arm 111, a bucket 112 which is a working machine device, a front vehicle body 110 having a tire (moving wheel) 113 and the like, and a rear vehicle body 120 having a cab 121, an engine compartment 122 and a tire 123 and the like. Ru. The arm 111 is pivoted (up and down) in the vertical direction by driving the arm cylinder 114, and the bucket 112 is pivoted (dump or cloud) in the vertical direction by driving the bucket cylinder 115. The front vehicle body 110 and the rear vehicle body 120 are pivotably connected to each other by a center pin 101, and the front vehicle body 110 is bent to the left and right with respect to the rear vehicle body 120 by the expansion and contraction of a steering cylinder (not shown).

FIG. 2 is a view showing a schematic configuration of the wheel loader 100. As shown in FIG. The output shaft of the engine (power source) 1 is connected to the input shaft (21 in FIG. 3) of a torque converter 2 (hereinafter referred to as torque converter), and the output shaft (22 in FIG. 3) of the torque converter 2 is connected to the transmission 3 It is done. The torque converter 2 is a fluid clutch comprising a known impeller, turbine and stator, and the rotation of the engine 1 is transmitted to the transmission 3 via the torque converter 2. The transmission 3 has a hydraulic pressure clutch that shifts its speed gear to 1st to 4th as described later, and the rotation of the output shaft of the torque converter 2 is shifted by the transmission 3. The rotation after transmission is transmitted to the

tires

113 and 123 via the propeller shaft 4 and the axle 5, and the wheel loader travels.

The axle 5 is provided with a brake portion 5 a for decelerating and stopping the wheel loader 100. When the brake fluid (working fluid) is supplied via the brake valve 32, the brake unit 5a generates a braking force corresponding to the pressure of the working fluid. The brake valve 32 is a pressure reducing valve that reduces the pressure oil supplied from the hydraulic pressure source 30 of the working oil to a pressure corresponding to the compression force of the spring 32a. When the brake pedal 31 provided in the driver's cab 121 is depressed by the operator, the spring 32 a is compressed according to the depression force of the brake pedal 31. Therefore, the brake valve 32 reduces the pressure oil supplied from the hydraulic pressure source 30 of the hydraulic oil to a pressure corresponding to the depression force of the brake pedal 31. The brake valve 32 reduces the pressure of the hydraulic fluid so that the higher pressure hydraulic fluid is supplied to the brake unit 5a as the compression force of the spring 32a (ie, the stepping force of the brake pedal 31) becomes higher. 34 is a hydraulic oil tank.

A working hydraulic pump (not shown) is driven by the engine 1, and the oil discharged from the hydraulic pump is guided to a working actuator (for example, arm cylinder 114) via a direction control valve (not shown). The direction control valve is driven by the operation of an operation lever (not shown), and can drive the actuator according to the amount of operation of the operation lever.

The torque converter 2 has a function to increase the output torque with respect to the input torque, that is, a function to make the torque ratio 1 or more. The torque ratio increases as the torque converter speed ratio e (= Nt / Ni), which is the ratio of the rotation speed Ni of the input shaft 21 of the torque converter 2 and the rotation speed Nt of the output shaft 22, decreases. For example, when the running load increases while running while the engine speed is constant, the number of rotations of the output shaft 22 of the torque converter 2, that is, the vehicle speed decreases, and the torque control speed ratio e decreases. At this time, since the torque ratio is increased, the vehicle can be driven with a larger driving force (traction force).

Here, the configuration of the transmission 3 will be described. FIG. 3 is a view showing a schematic configuration of the transmission 3. The transmission 3 includes a plurality of clutch shafts SH1 to SH3, an output shaft SH4, a plurality of gears G1 to G13, a forward hydraulic clutch (forward clutch) 18, a reverse hydraulic clutch (reverse clutch) 19 for 1 to 4 speeds Hydraulic clutches C1 to C4 of FIG. The

hydraulic clutches

18, 19 and C1 to C4 are engaged or released by pressure oil (clutch pressure) supplied via the transmission control device 20. That is, when the clutch pressure supplied to the

hydraulic clutches

18, 19 and C1 to C4 increases, the

clutches

18, 19 and C1 to C4 are engaged, and are released when the clutch pressure decreases.

The output shaft 22 of the torque converter 2 is connected to the clutch shaft SH1, and both ends of the output shaft SH4 are connected to the axle 5 at the front and rear of the vehicle via the propeller shaft 4 of FIG. In FIG. 3, the forward clutch 18 and the first speed clutch C1 are in the engaged state, and the other clutches 19 and C2 to C4 are in the released state. In this case, the gear G1 and the clutch shaft SH1 rotate integrally, and the gear G6 and the clutch shaft SH2 rotate integrally.

At this time, the output torque of the engine 1 is, as shown by a thick line in FIG. 3, the input shaft 21 of the torque converter 2, the output shaft 22, the clutch shaft SH1, the forward clutch 18, the gears G1, G3, G5, G6, and the first speed clutch C1. , And is transmitted to the output shaft SH4 via the clutch shaft SH2 and the gears G8 and G12. This enables first-speed travel.

When shifting from the first speed to the second speed, the clutch pressure supplied via the transmission control device 20 releases the first speed clutch C1 and engages the second speed clutch C2. As a result, the output torque of the engine 1 includes the input shaft 21 of the torque converter 2, the output shaft 22, the clutch shaft SH1, the forward clutch 18, the gears G1, G3 and G7, the second speed clutch C2, the clutch shaft SH2 and the gears G8 and G12. The electric power is transmitted to the output shaft SH4 to enable 2-speed travel. Similarly, clutches C1 to C4 are also used for shifting from 1st to 2nd, that is, from 2nd to 3rd, 3rd to 4th, 4th to 3rd, 3rd to 2nd, and 2nd to 1st. It is done by controlling.

There are two types of automatic shift control: torque converter speed ratio reference control that shifts when the torque converter speed ratio e reaches a predetermined value, and vehicle speed reference control that shifts when the vehicle speed reaches a predetermined value. In the present embodiment, the speed stage of the transmission 3 is controlled by torque converter speed ratio reference control.

FIG. 4 is a diagram showing the relationship between the torque converter speed ratio e and the speed stage. When the traveling load decreases and the torque converter speed ratio e increases and the torque converter speed ratio e becomes equal to or more than the predetermined value eu, the speed gear shifts up by one. As a result, the torque converter speed ratio e becomes e1 (ed <e1 <eu). On the contrary, when the traveling load increases and the torque converter speed ratio e decreases and the torque converter speed ratio e becomes equal to or less than the predetermined value ed, the speed gear shifts down by one. As a result, the torque converter speed ratio e becomes e2 (ed <e2 <eu). The predetermined values eu and ed are set in the controller 10 in advance.

The controller 10 shown in FIG. 2 includes an arithmetic processing unit having a CPU, a ROM, a RAM, and other peripheral circuits. The controller 10 includes a pedal operation amount detector 12a that detects the operation amount of the accelerator pedal 12, a rotation number detector 14 that detects the rotation speed Ni of the input shaft 21 of the torque converter 2, and rotation of the output shaft 22 of the torque converter 2. A rotation speed detector 15 for detecting the number Nt and a vehicle speed detector 16 for detecting the rotation speed of the output shaft of the transmission 3, that is, the vehicle speed v are connected. The controller 10 includes a forward / backward changeover switch 7 for instructing forward / backward movement of the vehicle, a shift switch 8 for instructing the maximum speed gear between the first and fourth speeds, and whether or not clutch cutoff (described later) is performed. A clutch cutoff selection switch 9 to be selected is connected. Further, the controller 10 switches the transmission means switching device 35 for switching whether the transmission in the transmission 3 is to be performed automatically or manually, and switches conditions for cutting off the forward and reverse

clutches

18 and 19 as described later. A clutch cutoff operation phase change switch 36 is connected.

The controller 10 is connected to a pedal operation amount detector 31 a that detects an operation amount of the brake pedal 31 and a pressure sensor 33 that detects the pressure of the hydraulic fluid supplied to the brake unit 5 a. The controller 10 controls the rotational speed (rotational speed) of the engine 1 in accordance with the operation amount of the accelerator pedal 12 detected by the pedal operation amount detector 12a.

For example, when loading the earth and sand into the dump truck with the wheel loader 100, etc., the operator depresses the brake pedal 31 when approaching the dump truck to decelerate the wheel loader 100, but moves the bucket 112 upward. In order to increase the speed, the accelerator pedal 12 is also depressed to maintain the rotational speed of the engine 1 at high speed. When the controller 10 selects the clutch cutoff selection switch 9 so as to cut off the clutch, the pressure (brake fluid pressure Plb) of the hydraulic fluid detected by the pressure sensor 33 is a predetermined value (brake fluid pressure) If it is judged that the target object (for example, a dump truck) approaching when loading earth and sand etc. is reached, for example, when it becomes the cut-off threshold Ps or more, the forward and reverse

clutches

18 and 19 are released ( A control signal (cut-off signal) for performing cut-off is output to the transmission control device 20. In the transmission control device 20, when the cutoff signal is received, the clutch cutoff valve 17 (FIG. 2) provided in the transmission control device 20 reduces the clutch pressure of the

clutches

18, 19. Thereby, the

clutches

18 and 19 are released, and the transmission of the traveling driving force (hereinafter simply referred to as driving force) is interrupted.

That the

clutches

18 and 19 are released and the connection between the engine driving the input shaft 21 of the torque converter 2 and the propeller shaft 4 connected to the output shaft SH4 of the transmission 3 is cut off is called clutch cutoff.
In the following description, a condition for determining whether or not the wheel loader 100 has approached an approaching object in order to perform clutch cutoff is referred to as an approach determination condition. Since it is determined that the object to approach is approached, the clutch cutoff is performed, the approach determination condition is also referred to as a clutch cutoff condition. The approach determination condition (clutch cut-off condition) is held by the determination

value setting units

10 a and 10 b of the controller 10. Each determination

value setting unit

10a or 10b has a plurality of approach determination conditions. The approach determination condition will be described later. When the clutch cutoff selection switch 9 is selected so that the clutch cutoff is not performed, the controller 10 does not output the cutoff signal even if the approach determination condition is satisfied. Therefore, when the clutch cutoff selection switch 9 is selected so as not to perform the clutch cutoff, the above-described clutch cutoff is not performed.

FIG. 5 is a view showing V shape loading which is one of the methods of loading soil and the like into a dump truck. In the V shape loading, first, as indicated by the arrow a, the wheel loader 100 is advanced to scoop soil and the like, and then, as indicated by the arrow b, the wheel loader 100 is temporarily retreated. Then, as indicated by the arrow c, the wheel loader 100 is advanced toward the dump truck, the scooped soil etc. is loaded on the dump truck, and as shown by the arrow d, the wheel loader 100 is retracted to the original position. .

When loading earth and sand etc. into the dump truck indicated by arrow c in FIG. 5, a large driving force is not necessary as in the case of excavation, so the operator sets the maximum speed stage to two by the shift switch 8 Alternatively, the speed gear is set to be fixed to the second speed after switching by the speed change means switching device 35 so as to manually perform the speed change in the transmission 3.

FIG. 6 is a view for explaining the state of the wheel loader 100 at the time of loading of the earth and sand etc. onto the dump truck indicated by the arrow c in FIG. For convenience of explanation, the step of accelerating the wheel loader 100, which is the initial stage of approaching (approaching) the dump truck which is the approaching object, is referred to as the initial stage of the approach. A step in the middle stage when approaching the dump truck, which starts to decelerate the wheel loader 100 until the wheel loader 100 stops, is called an approach middle stage. The stage from when the wheel loader 100 stops to when earth and sand etc. in the bucket 112 are dumped into the dump truck is called an approach late stage.

As shown in FIG. 6, at the beginning of the approach, the accelerator pedal 12 is fully depressed to accelerate the wheel loader 100 and raise the bucket 112. In the middle approach, the accelerator pedal 12 is fully depressed to lift the bucket 112, but the brake pedal 31 is also gradually depressed to decelerate the wheel loader 100. In the late approach, the brake pedal 31 is fully depressed to keep the wheel loader 100 stationary. When the clutch cutoff selection switch 9 is selected to perform the clutch cutoff, as described above, when the approach determination condition described later is satisfied, such as by the depression of the brake pedal 31 by the operator in the middle stage of the approach. Clutch cutoff is performed.

When the clutch cutoff is performed, the transmission of the driving force is cut off when approaching the dump truck, so it is not necessary to decelerate and stop the wheel loader 100 against the driving force. Thereby, the load on the brake 5a can be reduced compared to when the wheel loader 100 is decelerated and stopped against the driving force without clutch cutoff, and the temperature rise of the brake 5a is suppressed. The consumption of each part of the brake unit 5a can be suppressed. Further, even if the wheel loader 100 is decelerated and stopped while maintaining the state where the rotational speed of the engine 1 is high, the torque converter speed ratio e which is the rotational speed ratio between the input shaft 21 and the output shaft 22 is approximately 1 Since the input torque from the engine 1 to the torque converter 2 is very small, the power loss in the torque converter 2 can be reduced to reduce the fuel consumption.

However, when the timing of the clutch cutoff is not appropriate, the transmission of the driving force is suddenly cut off by the clutch cutoff, so the driving force of the wheel loader 100 is rapidly reduced and the pitch of the wheel loader 100 is reduced. There is a risk of triggering. When carrying out an operation to load soil, etc., since the position of the bucket 112 is high, the pitching of the wheel loader 100, which is called pitching, tends to be larger. Therefore, when the operator who dislikes pitching performs work to load earth and sand etc. on a dump truck with a conventional wheel loader, etc., the clutch cut-off selection switch 9 is selected so as not to cut off the clutch, and the clutch described above There are cases where the cutoff is not made.

In this case, although there is no risk of inducing the pitching as described above, the consumption of each part of the brake portion 5a and the increase of the power loss in the torque converter 2 are caused. Therefore, in the wheel loader 100 of the present embodiment, the clutch cutoff timing is made appropriate by setting the approach determination condition to the condition described below.

--- Approach determination condition (clutch cut-off condition) ---
In the present embodiment, when the clutch cut-off operation phase change switch 36 is set to the first phase, the controller 10 satisfies one of the following two conditions (a) and (b): If determined, the cutoff signal is output to the transmission control device 20.
(A) When the brake hydraulic pressure Plb detected by the pressure sensor 33 becomes equal to or greater than the first brake hydraulic pressure cut-off threshold Ps1, and the torque converter speed ratio e becomes equal to or smaller than the first threshold es1. (B) When the brake hydraulic pressure Plb detected by the pressure sensor 33 becomes equal to or higher than the second brake hydraulic pressure cutoff threshold Ps2.
The torque converter speed ratio e is calculated from the rotation speed Ni of the input shaft 21 of the torque converter 2 detected by the

rotation speed detectors

14 and 15, and the rotation speed Nt of the output shaft 22.

Here, the first brake hydraulic pressure cut-off threshold value Ps1 is, for example, an operation of loading soil and the like on a flat surface, etc., and when the speed stage is set to the second speed and the accelerator pedal 12 approaches the approaching object, The value is equivalent to the brake fluid pressure Plb that generates a braking force that can reduce the vehicle speed to, for example, about 7 to 8 km / h against the driving force even if the vehicle is stepped on to the maximum. That is, the first brake hydraulic pressure cutoff threshold Ps1 corresponds to, for example, the brake hydraulic pressure Plb that generates a weak braking force at the start of application of the brake in the middle stage of the approach described above.

The first threshold es1 is, for example, an operation of loading soil and the like on a flat surface, etc., and the speed gear is set to the second speed, and the accelerator pedal 12 is fully depressed when approaching the approaching object. When the vehicle speed is lowered to, for example, 7 to 8 km / h by applying the brake, a value corresponding to the torque converter speed ratio e is set. That is, the first threshold value es1 corresponds to, for example, the torque converter speed ratio e when the vehicle speed is lowered to about 7 to 8 km / h when the brake is applied in the middle stage of the above-described approach. The first threshold value es1 is set to, for example, about 0.6. The optimum value as the first threshold es1 varies depending on the capacity of the torque converter 2, the performance of the brake, the vehicle weight, and the like, so the first threshold es1 may not be 0.6.

The second brake hydraulic pressure cut-off threshold value Ps2 is set, for example, to load the soil on a flat surface, etc., and the accelerator pedal 12 is maximized when the speed stage is set to the second speed and approaches the approaching object. If it is stepped on, the brake fluid pressure Plb generates a braking force that can reduce the vehicle speed to, for example, 2 to 3 km / h against the traveling drive force without stopping the wheel loader 100 completely. It corresponds to the corresponding value. In other words, the second brake hydraulic pressure cutoff threshold Ps2 is a value that is higher than the first brake hydraulic pressure cutoff threshold Ps1 and corresponds to the brake hydraulic pressure Plb that generates a braking force that can be a sudden brake, The value is about half the value of the brake fluid pressure Plb generated when the operator having a typical leg strength depresses the brake pedal 31 with full force. The second brake hydraulic pressure cut-off threshold Ps2 is a brake hydraulic pressure Plb corresponding to the braking force at the final stage (immediately before the stop of the wheel loader 100) of the middle stage of the approach.

By setting the approach determination condition when the clutch cutoff operation phase switching switch 36 is set to the first phase as described above, in a state where the accelerator pedal 12 is fully depressed in the middle stage of the approach described above When the vehicle speed is lowered to, for example, about 7 to 8 km / h by application of the brake, the condition of (a) described above is satisfied, and clutch cutoff is performed. In addition, when the brake fluid pressure Plb is equal to or higher than the second brake fluid pressure cut-off threshold Ps2 after the strong brake is applied, the above-mentioned (b And the clutch cut-off is performed.

Under the condition of (a) described above, the brake is applied in the middle stage of the approach, and the clutch cutoff is performed when the vehicle speed falls to a certain extent, so the clutch cutoff timing becomes appropriate. Can be suppressed. Further, under the condition (b) described above, although the clutch cutoff is performed regardless of the vehicle speed when the strong brake is applied, the clutch cutoff is performed in a state where the braking force is relatively strong. Therefore, the pitching of the wheel loader 100 can be suppressed.

--- If you climb a steep slope ---
For example, when the loading operation is performed while going up a steep slope (for example, the inclination angle is about 20 degrees), such as the loading operation to the hopper, the direction in which the wheel loader 100 lowers the weight of the wheel loader 100 ( In order to act as a traveling load in the backward direction), if the clutch cutoff is performed under the same conditions as a flat ground, the timing of the clutch cutoff is too early. When the timing of the clutch cutoff is too early, the traveling drive force is cut off by the clutch cutoff in a state where the braking force is not sufficient, and the wheel loader 100 starts to descend the slope on the contrary. In this case, since the operator further depresses the brake pedal to stop the wheel loader 100, the wheel loader 100 may suddenly stop to induce the pitching as described above.

Therefore, in the present embodiment, when the clutch cutoff operation phase switching switch 36 is set to the second phase, compared with the case where the clutch cutoff operation phase switching switch 36 is set to the first phase. The approach determination condition is set such that the clutch cutoff timing is delayed (so that the clutch cutoff is difficult to be performed). Specifically, when the clutch cut-off operation phase changeover switch 36 is set to the second phase, the controller 10 determines that one of the following two conditions (c) and (d) is satisfied. Then, a cutoff signal is output to the transmission control device 20.
(C) When the brake hydraulic pressure Plb detected by the pressure sensor 33 becomes equal to or higher than the third brake hydraulic pressure cut-off threshold Ps3 and the torque converter speed ratio e becomes equal to or smaller than the second threshold es2. (D) When the brake hydraulic pressure Plb detected by the pressure sensor 33 becomes equal to or higher than the fourth brake hydraulic pressure cutoff threshold Ps4.

Here, the third brake fluid pressure cut-off threshold Ps3 is, for example, a braking force to such an extent that the wheel loader 100 does not lower the slope even if the

clutches

18 and 19 are released on the slope with an inclination angle of about 20 degrees. The value corresponds to the brake fluid pressure Plb to be generated. That is, the third brake hydraulic pressure cut-off threshold Ps3 is, for example, the wheel loader 100 performs the ramp on the slope even if the clutch cutoff is performed on the slope having an inclination angle of about 20 degrees in the loading operation to the hopper or the like. The brake fluid pressure is set to a value corresponding to the brake fluid pressure Plb that generates the braking force to such an extent that the brake pedal does not need to be further stepped on in order to prevent the vehicle from falling. The third brake hydraulic pressure cutoff threshold Ps3 is higher than the first brake hydraulic pressure cutoff threshold Ps1, and lower than the second brake hydraulic pressure cutoff threshold Ps2.

The second threshold es2 is, for example, a slope having an inclination angle of about 20 degrees, and the accelerator pedal 12 is fully depressed when the speed stage is set to the first speed and approaches the approaching object. Is set to a value corresponding to the torque converter speed ratio e when the vehicle speed drops to, for example, about 1 to 2 km / h. For example, 0.3 is set as the second threshold es2. The second threshold es2 may not be 0.3 because the optimum value as the second threshold es2 varies depending on the capacity of the torque converter 2, the performance of the brakes, the vehicle weight, and the like.

The fourth brake hydraulic pressure cut-off threshold Ps4 is such that, for example, the clutch is turned off whenever the operator depresses the brake pedal 31 with full force. The value is, for example, about 80 to 90% of the brake fluid pressure Plb generated when the driver is depressed. The fourth brake hydraulic pressure cutoff threshold Ps4 has a value higher than the second brake hydraulic pressure cutoff threshold Ps2.

By setting the approach determination condition when the clutch cut-off operation stage changeover switch 36 is set to the second stage as described above, for example, the slope angle of about 20 degrees climbs up the slope and the hopper When the accelerator pedal 12 is fully depressed when the accelerator pedal 12 is depressed when the vehicle speed is lowered to, for example, 1 to 2 km / h, the above condition (c) is satisfied. Clutch cutoff is performed. In addition, when the brake pedal 31 is strongly depressed and the brake hydraulic pressure Plb becomes equal to or higher than the fourth brake hydraulic pressure cut-off threshold Ps4, as described above, even if the vehicle speed is not reduced to about 1 to 2 km / h The condition of d) is satisfied and a clutch cutoff is performed.

Under the condition of (c) described above, the wheel loader 100 is inclined on the slope even if the vehicle speed is reduced to approximately 1 to 2 km / h and the

clutches

18 and 19 are released on the slope whose inclination angle is approximately 20 degrees. If the braking force is not generated to such an extent that it does not decrease, the clutch cutoff can not be performed. Therefore, even if clutch cutoff is performed, the wheel loader 100 does not start to descend the slope, and as described above, the operator does not have to further depress the brake pedal to stop the wheel loader 100. There is no danger that 100 will stop suddenly and induce pitching as described above. Further, under the condition (d) described above, although the clutch cutoff is performed regardless of the vehicle speed when the brake is strongly applied, the clutch cutoff is performed in the state where the braking force is strong, so the wheel Pitching of the loader 100 can be suppressed.

--- If you go down a steep slope ---
When loading earth and sand etc. while going down a steep slope (for example, the inclination angle is about 20 degrees), the wheel loader 100 travels in the direction in which the wheel loader 100 descends (forward movement direction) Act as a force to try. Therefore, since the braking force is required more than on a flat ground, the amount of depression of the brake is large, and if the clutch cut off is performed under the same conditions as on a flat ground, the timing of the clutch cut off is too early. Therefore, to make the clutch cutoff timing substantially the same as in the case of a flat ground, the brake fluid pressure cutoff threshold Ps as a condition for performing the clutch cutoff is set to a value larger than the first brake hydraulic pressure cutoff threshold Ps1. There is a need to.

As described above, when the clutch cut-off operation phase change switch 36 is set to the second phase, clutch cut-off is performed as compared with the case where the clutch cut-off operation phase change switch 36 is set to the first phase. The approach determination condition is set so that the off timing is delayed (so that the clutch cutoff is difficult to be performed). Therefore, when going down a steep slope, the operator may set the clutch cutoff operation phase switching switch 36 to the second phase, whereby the clutch cutoff timing is set to the clutch cutoff timing on a flat surface. It can be approached.

---flowchart---
FIG. 7 is a flowchart showing the operation of the clutch control process in the wheel loader 100 of the present embodiment. When an ignition switch (not shown) of the wheel loader 100 is turned on, a program for performing the process shown in FIG. 7 is started and repeatedly executed by the controller 10. In step S1, the information of the brake hydraulic pressure Plb detected by the pressure sensor 33, and the rotation speed Ni of the input shaft 21 of the torque converter 2 and the rotation speed Nt of the output shaft 22 detected by the

rotation speed detectors

14 and 15. Information is acquired and it progresses to step S3. In step S3, it is determined whether the clutch cutoff selection switch 9 is selected so as to perform clutch cutoff.

If the determination in step S3 is affirmative, that is, if it is determined that the clutch cutoff selection switch 9 is selected so as to perform the clutch cutoff, the process proceeds to step S5, and the clutch cutoff operation phase switching switch 36 It is determined whether the stage is set. If the determination in step S5 is affirmative, that is, if it is determined that the clutch cutoff operation step switch 36 is set to the first step, the process proceeds to step S7, and the brake hydraulic pressure Plb acquired in step S1 is the second It is determined whether or not the brake fluid pressure cut-off threshold Ps2 or more is satisfied. If the determination in step S7 is negative, the process proceeds to step S9, in which it is determined whether the brake hydraulic pressure Plb acquired in step S1 is equal to or greater than a first brake hydraulic pressure cutoff threshold Ps1.

If the determination in step S9 is affirmative, the process proceeds to step S11, and the torque converter speed ratio e is calculated from the rotation speed Ni of the input shaft 21 of the torque converter 2 and the rotation speed Nt of the output shaft 22 acquired in step S1 It is determined whether e is equal to or less than a first threshold es1. If the determination in step S11 is affirmative, the process proceeds to step S13, where the above-described cutoff signal is output to the transmission control device 20, and the process returns.

If the determination in step S7 is affirmative, the process proceeds to step S13.

If the determination in step S5 is negative, that is, if it is determined that the clutch cutoff operation step switch 36 is set to the second step, the process proceeds to step S17, and the brake hydraulic pressure Plb acquired in step S1 is the fourth It is determined whether or not the brake hydraulic pressure cut-off threshold Ps4 or more is satisfied. If the determination in step S17 is negative, the process proceeds to step S19, in which it is determined whether the brake hydraulic pressure Plb acquired in step S1 is equal to or greater than a third brake hydraulic pressure cutoff threshold Ps3.

If the determination in step S19 is affirmative, the process proceeds to step S21, and the torque converter speed ratio e is calculated from the rotation speed Ni of the input shaft 21 of the torque converter 2 and the rotation speed Nt of the output shaft 22 obtained in step S1 It is determined whether e is equal to or less than a second threshold es2. If the determination in step S21 is affirmative, the process proceeds to step S13.

If the determination in step S17 is affirmative, the process proceeds to step S13.

If step S3 is determined to be negative, step S9 is determined to be negative, step S11 is determined to be negative, step S19 is determined to be negative, or step S21 is determined to be negative, the process returns.

According to the present embodiment, the following effects can be achieved.
(1) When the clutch cutoff selection switch 9 is selected to perform the clutch cutoff, the clutch cutoff is performed when the above-described approach determination condition is satisfied. Thus, the timing of the clutch cutoff can be appropriately set in accordance with the working state of the wheel loader 100, so that the movement of the wheel loader 100 becomes smooth.

(2) When the clutch cutoff operation phase changeover switch 36 is set to the first stage, the brake hydraulic pressure Plb detected by the pressure sensor 33 becomes equal to or higher than the first brake hydraulic pressure cutoff threshold Ps1, and The clutch cutoff is performed when the torque ratio e becomes equal to or less than the first threshold es1. In addition, when the clutch cutoff operation phase switching switch 36 is set to the second phase, the brake hydraulic pressure Plb detected by the pressure sensor 33 becomes equal to or higher than the third brake hydraulic pressure cutoff threshold Ps3, and The clutch cutoff is performed when the speed ratio e becomes equal to or less than the second threshold es2. Thus, the timing for performing the clutch cutoff is determined not only for the operating state of the brake but also for the traveling state of the wheel loader 100, etc. Therefore, even if the traveling state of the wheel loader 100 changes, the clutch cutoff timing is Properly done, the motion of the wheel loader 100 is smooth.

(3) When the clutch cutoff operation phase changeover switch 36 is set to the first stage, the brake fluid pressure Plb detected by the pressure sensor 33 is the second brake fluid pressure cut regardless of the torque converter speed ratio e. The clutch cutoff is performed when the off threshold value Ps2 or more is reached. Further, when the clutch cutoff operation phase switching switch 36 is set to the second phase, the brake fluid pressure Plb detected by the pressure sensor 33 is the fourth brake fluid pressure cutoff regardless of the torque converter speed ratio e. The clutch cutoff is performed when the threshold value Ps4 or more is reached. Thus, for example, when loading earth and sand into a dump truck, etc., if the brake is strongly applied to stop the wheel loader 100 completely, regardless of the traveling state (torque speed ratio e) of the wheel loader 100. As a result, a clutch cutoff will be performed. Therefore, compared with the case where the wheel loader 100 is decelerated and stopped against the driving force without clutch cutoff, the load on the brake portion 5a can be reduced, and the temperature rise of the brake portion 5a is suppressed. It is possible to suppress the consumption of each part of the brake unit 5a.

(4) The operator can select either the first stage or the second stage by means of the clutch cut-off operation stage changeover switch 36. Thus, the operator can appropriately set the timing for performing the clutch cutoff in accordance with the inclination of the road on which the work is performed. In addition, by setting the selection options by the clutch cutoff operation phase switching switch 36 to two in the first stage and the second stage, which option should be selected by the operator as compared with the case where there are more options It is possible to reduce the burden on the operator and reduce the number of times of switching the options.

(5) As described in the above (2), when the clutch cutoff operation phase switching switch 36 is set to the first phase, the brake hydraulic pressure Plb detected by the pressure sensor 33 is the first brake. The clutch cutoff is performed when the hydraulic pressure cut-off threshold Ps1 or more and the torque converter speed ratio e becomes equal to or smaller than the first threshold es1. In addition, when the clutch cutoff operation phase switching switch 36 is set to the second phase, the brake hydraulic pressure Plb detected by the pressure sensor 33 becomes equal to or higher than the third brake hydraulic pressure cutoff threshold Ps3, and The clutch cutoff is performed when the speed ratio e becomes equal to or less than the second threshold es2.
That is, in the first stage as well as in the second stage, a plurality of approach determination conditions are set, and clutch cutoff control is performed based on each approach determination condition and the detection value sent from the detector 33. Therefore, appropriate brake control can be set according to the degree of approach to the approaching object, and the movement of the industrial vehicle can be smoothed.

(6) A plurality of determination

value setting units

10a and 10b are provided in the approach determination unit, and, for example, a plurality of approach determination conditions in work on a flat surface and a plurality of approach determination conditions in a steep slope, for example The determination

value setting units

10a and 10b of FIG. A plurality of approach determination conditions are set in each of the determination

value determination units

10a and 10b, and as described in the item (5) above, appropriate clutch cutoff control can be performed, and further, an industrial It is possible to make adjustments so that appropriate clutch cutoff control can be performed according to the working conditions of the vehicle.

--- Modifications ---
(1) Although the torque converter speed ratio e is considered as the approach determination condition in the above description, the present invention is not limited to this. For example, instead of the torque converter speed ratio e, the vehicle speed of the wheel loader 100 may be taken into consideration. In this case, for example, the above-mentioned condition (a) “The brake hydraulic pressure Plb detected by the pressure sensor 33 is equal to or higher than the first brake hydraulic pressure cutoff threshold Ps1 and the vehicle speed is equal to or lower than the first threshold Vs1. It may be "when". Further, for example, the condition (c) is “when the brake hydraulic pressure Plb detected by the pressure sensor 33 is equal to or higher than the third brake hydraulic pressure cutoff threshold Ps3 and the vehicle speed is equal to or lower than the second threshold Vs2 It is good also as ". Here, for example, the first threshold value Vs1 may be approximately 7 to 8 km / h. Further, for example, the second threshold Vs2 may be set to about 1 to 2 km / h.

(2) In the above description, the brake fluid pressure Plb is considered as the approach determination condition, but the present invention is not limited to this. Instead of the brake fluid pressure Plb, for example, the proximity determination of the operation amount (pedal stroke or pedal angle) of the brake pedal 31 detected by the pedal operation amount detector 31a or the depression force of the brake pedal 31 detected by a detector (not shown) It may be considered as a condition. That is, the parameter to be considered as the approach determination condition is not limited to the brake fluid pressure Plb, as long as the parameter can detect the brake operating state (the magnitude of the braking force) directly or indirectly.

(3) In the above description, when the clutch cutoff is performed, the controller 10 outputs the cutoff signal for cutoff the forward and reverse

clutches

18 and 19 to the transmission control device 20. However, the present invention is not limited thereto. For example, the controller 10 may be configured to output a cutoff signal to the transmission control device 20 so as to cut off only the clutch that is engaged at the time of performing the clutch cutoff. That is, the controller 10 is configured to output a cutoff signal to the transmission control device 20 so as to cut off only the forward clutch 18 when performing the clutch cutoff while the wheel loader 100 is moving forward. You may

(4) Although the number of selectable speed stages in the transmission 3 is four in the above description, the present invention is not limited to this, and may be three or five or more. Further, in the above description, the wheel loader 100 has been described as an example of the work vehicle, but the present invention is not limited to this, and may be another work vehicle such as a forklift.
(5) Each embodiment and modification mentioned above may be combined, respectively.

The present invention is not limited to the embodiment described above, and an approach judging device for judging whether an industrial vehicle approaches an approaching object and an industrial vehicle to an approaching object by an approach judging device If it judges that it approached, the clutch control device of the industrial vehicle of various structures provided with the clutch controller which controls engagement / release of an advance clutch so that an advance clutch may be released is included.

The disclosure content of the following priority basic application is incorporated herein by reference.
Japanese Application Patent Application 2009 No. 144092

Claims

An approach detector that determines whether the industrial vehicle has approached the approaching object;
An industrial vehicle including a clutch controller that controls engagement / disengagement of the forward clutch so as to release the forward clutch when the approach determiner determines that the industrial vehicle approaches the approaching object; Clutch control device.
In the clutch control device for an industrial vehicle according to claim 1,
The approach determiner determines that the speed ratio of a torque converter for transmitting the power of the engine to the transmission is less than a predetermined speed ratio and the travel speed of the industrial vehicle is less than a predetermined speed, and the braking force of the industrial vehicle The clutch control device of the industrial vehicle which judges that the said industrial vehicle approached the approach target object, when the conditions which are more than predetermined | prescribed braking force are satisfied.
In the clutch control device for an industrial vehicle according to claim 1,
The approach determiner is configured such that the braking force of the industrial vehicle is such that the traveling speed of the industrial vehicle is less than a predetermined speed against the traveling driving force of the industrial vehicle when approaching the approaching object. The clutch control device of the industrial vehicle which judges that the said industrial vehicle approached the approach target object when it is judged that it is more than damping | braking force.
In the clutch control device for an industrial vehicle according to claim 2,
The system further comprises selection means for causing the user to select whether the predetermined braking force is a first braking force or a second braking force larger than the first braking force.
The clutch control means selects that the predetermined braking force is the first braking force by the selection means when the predetermined braking force is selected by the selection means as the second braking force. A clutch control device for an industrial vehicle, which controls engagement / release of the forward clutch so that the forward clutch is less likely to be released as compared to the case where the forward clutch is engaged.
In the clutch control device for an industrial vehicle according to claim 3,
And a selector for causing the user to select whether the predetermined braking force is a third braking force or a fourth braking force greater than the third braking force.
The clutch controller selects that the predetermined braking force is the second braking force in the selector when the predetermined braking force is selected in the selector as the fourth braking force. A clutch control device for an industrial vehicle, which controls engagement / release of the forward clutch so that the forward clutch is less likely to be released as compared to the case where the forward clutch is engaged.