JP5270464B2 - Shift control device for industrial vehicle - Google Patents

Description

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

  2. Description of the Related Art Conventionally, as a shift control device for an industrial vehicle such as a wheel loader, a device that automatically changes a transmission speed stage when a vehicle speed reaches a set speed is known. For example, in a wheel loader, when carrying out the work of loading earth and sand on a dump truck, if the speed stage is changed when approaching the dump truck, the vehicle speed may change unintentionally. Therefore, there is known a transmission configured to maintain the speed stage at that time when the height position of the work equipment (bucket) calculated from the angle of the lift arm becomes equal to or higher than the set height. (See Patent Document 1).

Japanese Patent No. 2529106

  However, in the above-described transmission, when the engine speed is set to be lower as the engine speed is lower, the set speed of the accelerator is decreased. If the engine speed is low, the vehicle speed may reach the set speed before the bucket reaches the set height described above, and an upshift may occur unintentionally. Since the wheel loader is accelerated by this shift-up, the wheel loader approaches the dump truck earlier than expected by the wheel loader operator. In this case, the wheel loader operator must apply the brake to stop the wheel loader and raise the bucket to a height where he can load the dump truck. As a result, the work efficiency may be reduced.

(1) A shift control apparatus for an industrial vehicle according to a first aspect of the invention includes a vehicle speed detection means for detecting a vehicle speed, an engine rotation speed detection means for detecting the rotation speed of the engine, and a transmission speed stage being shifted up and down. A shift control means for permitting a shift up by the shift means when the vehicle speed detected by the vehicle speed detection means exceeds the shift up permission vehicle speed, and a work implement apparatus height for detecting the height position of the work implement apparatus. A position detection unit, and a shift-up permission vehicle speed change unit that raises a shift-up permission vehicle speed when the height position of the work machine device detected by the work machine device height position detection unit is equal to or higher than a first set value; It is characterized by providing.
(2) According to a second aspect of the present invention, in the shift control device for an industrial vehicle according to the first aspect, the speed stage of the transmission is 3 speeds or more, and the shift-up permission vehicle speed is determined by the speed control means of the speed stage of the transmission. It is a threshold value for permitting the upshift from the second speed to the third speed.
(3) According to a third aspect of the present invention, in the shift control device for an industrial vehicle according to the first aspect, the shift control means is configured such that the height position of the work implement device detected by the work implement device height position detection means is the first position. When the value is equal to or higher than the second set value higher than the set value of 1, the shift-up by the speed change means is prohibited.

  According to the present invention, it is possible to suppress a decrease in work efficiency.

It is a side view of the wheel loader which is an example of a work vehicle. It is a figure which shows schematic structure of a transmission control apparatus. It is a figure which shows the relationship between the vehicle speed v and a speed stage. It is a figure which shows the travel performance of the wheel loader 100. FIG. It is a figure shown about V shape loading. It is a figure explaining the change of the speed stage of the transmission 3 at the time of loading of earth and sand etc. by a prior art. It is a figure explaining the change of the speed stage of the transmission 3 at the time of loading of earth and sand, etc. at the time of applying this invention. 5 is a flowchart showing an operation of a shift control process of the transmission 3.

  Hereinafter, an embodiment of a shift control device for an industrial vehicle according to the present invention will be described with reference to FIGS. FIG. 1 is a side view of a wheel loader that is an example of a work vehicle to which the shift control device according to the present embodiment is applied. The wheel loader 100 includes an arm 111, a front body 110 having a bucket 112 as a work implement device, a tire 113, and the like, and a rear body 120 having an operator cab 121, an engine compartment 122, a tire 123, and the like. The arm 111 rotates up and down (up and down) by driving the arm cylinder 114, and the bucket 112 rotates up and down (dump or cloud) by driving the bucket cylinder 115. The front vehicle body 110 and the rear vehicle body 120 are rotatably connected to each other by a center pin 101, and the front vehicle body 110 is refracted left and right with respect to the rear vehicle body 120 by expansion and contraction of a steering cylinder (not shown).

  FIG. 2 is a diagram showing a schematic configuration of the shift control apparatus according to the present embodiment. An output shaft (not shown) of the torque converter 2 (hereinafter referred to as torque converter) is connected to the output shaft of the engine 1, and an output shaft (not shown) of the torque converter 2 is connected to the transmission 3. The torque converter 2 is a fluid clutch including 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 clutch that shifts the speed stage from the first speed to the fourth speed, and the rotation of the output shaft of the torque converter 2 is shifted by the transmission 3. The rotation after the shift is transmitted to the tires 113 and 123 via the propeller shaft 4 and the axle 5, and the wheel loader travels. The engine speed of the engine 1 is detected by an engine speed sensor 25.

  The working hydraulic pump 6 is driven by the engine 1, and the oil discharged from the hydraulic pump 6 is guided to the working actuator 8 (for example, the arm cylinder 114) via the direction control valve 7. The direction control valve 7 is driven by the operation of the operation lever 9 and can drive the actuator 8 in accordance with the operation amount of the operation lever 9. The height of the bucket 112 is calculated by the controller 10 based on a detection value of a sensor (bucket height detection sensor) 26 for detecting the bucket height. The bucket height detection sensor 26 is, for example, a sensor that detects the angle of the arm 111 with respect to the front vehicle body 110 and a sensor that detects the angle of the bucket 112 with respect to the arm 111. That is, the height of the bucket 112 is calculated by the controller 10 based on the detection values of these sensors and information such as the length and shape of the arm 111 and the mounting position stored in advance.

  The torque converter 2 has a function of increasing the output torque with respect to the input torque, that is, a function of setting the torque ratio to 1 or more. The torque ratio decreases as the torque converter speed ratio e (= Nt / Ni), which is the ratio between the rotational speed Ni of the input shaft of the torque converter 2 and the rotational speed Nt of the output shaft, increases. For example, when the traveling load increases during traveling with the engine speed kept constant, the rotational speed of the output shaft of the torque converter 2, that is, the vehicle speed decreases, and the torque converter speed ratio e decreases. At this time, since the torque ratio increases, the vehicle can travel with a larger driving force (traction force).

  The transmission 3 is an automatic transmission having a solenoid valve corresponding to each speed stage. These solenoid valves are driven by a control signal output from the controller 10 to the transmission control device 20, whereby the speed stage is automatically changed between the first speed to the fourth speed. In the present embodiment, the speed stage of the transmission 3 is provided from 1st speed stage to 4th speed stage, for example.

  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 vehicle speed reference control.

  FIG. 3 is a diagram showing the relationship between the vehicle speed v and the speed stage. In the present embodiment, the controller 10 outputs a control signal to the transmission control device 20 according to the vehicle speed v, and shifts the transmission 3 according to the vehicle speed v as shown in FIG. In other words, when the vehicle speed v increases to the shift permission vehicle speed v12, the first speed is shifted up to the second speed, and when the vehicle speed v increases from the shift permission vehicle speed v12 to the shift permission vehicle speed v23, the second speed is shifted up to the third speed. Increases from the shift permission vehicle speed v23 to the shift permission vehicle speed v34, the gear shifts from the third speed to the fourth speed. On the other hand, when the vehicle speed v decreases to the gear shift permission vehicle speed v43, the gear shifts down from the fourth gear to the third gear, and when the vehicle speed v decreases to the gear shift permission vehicle speed v32, the vehicle speed v shifts down from the third gear to the second gear. When it decreases to v21, it shifts down from 2nd gear to 1st gear. Note that the shift permission vehicle speeds v12, v23, and v34 are set larger than the shift permission vehicle speeds v21, v32, and v43, respectively, so that the shift change can be performed stably. Each of these shift permission vehicle speeds is a threshold value for permitting upshifting or downshifting, and is set in the controller 10 in advance. The transmission control device 20 is configured by a solenoid valve corresponding to each speed stage, and is driven by a control signal from the controller 10.

  In the present embodiment, the controller 10 decreases each shift permission vehicle speed if the rotation speed of the engine 1 is low, and increases each shift permission vehicle speed if the rotation speed of the engine 1 is high. In this way, the controller 10 changes each shift-permitted vehicle speed according to the number of revolutions of the engine 1, which is effective in reducing fuel consumption.

  FIG. 4 is a diagram showing the traveling performance of the wheel loader 100 of the present embodiment. For convenience of explanation, FIG. 4 shows only the speed change permission speed at the time of upshifting (shift up permission speed), but the same applies to the speed change permission speed at the time of downshifting (shift down permission speed). Intersection points x1, x2, and x3 of the curves indicating the traveling performance at each speed stage move as indicated by arrows a1, a2, and a3 when the rotational speed of the engine 1 decreases. Each speed change permission speed is generally set at the intersection points x1, x2, and x3. In FIG. 4, vehicle speed ranges indicated by A, B, and C indicate ranges in which the shift permission speeds v <b> 12, v <b> 23, and v <b> 34 change according to the rotational speed of the engine 1, respectively.

  In the present embodiment, the first set height and the second set height are determined in advance as the height of the bucket 112. When the height of the bucket 112 exceeds the first set height, the controller 10 increases the shift permission speeds v23 and v34 to the shift permission speeds v23a and v34a shown in FIG. 4 regardless of the rotational speed of the engine 1. (Up), it is difficult to shift up from 2nd to 3rd and from 3rd to 4th. Further, when the height of the bucket 112 exceeds the second set height which is higher than the first set height, the controller 10 prohibits the shift-up from the second speed to the third speed and the shift-up from the third speed to the fourth speed. To do. Here, the shift permission speeds v23a and v34a are set to be, for example, about 10% higher than the maximum values of the shift permission speeds v23 and v34 that change according to the rotation speed of the engine 1. Even if the height of the bucket 112 exceeds the second set height, the downshift is not prohibited.

  The first set height is set to, for example, the height of the bucket 112 in the transporting posture, that is, the height of the bucket 112 when the lower end (lower surface) of the bucket 112 is located near the lowest ground level of the wheel loader 100. Yes. Note that the first set height may be set to a height between the height of the bucket 112 in the transporting posture and the height of the bucket 112 at the time of maximum reach where the arm 111 is substantially horizontal. Here, the state in which the arm 111 is substantially horizontal is a state in which the swing center of the proximal end of the arm 111 and the swing center of the bucket 112 at the distal end are substantially horizontal. For example, the second set height is set to the height of the bucket 112 at the time of the maximum reach.

  The controller 10 shown in FIG. 2 includes an arithmetic processing unit having a CPU, ROM, RAM, and other peripheral circuits. The controller 10 includes a pedal operation amount detector 12 that detects the operation amount of the accelerator pedal 11, a rotation number detector 13 that detects the rotation number Ni of the input shaft (not shown) of the torque converter 2, and a torque converter 2 (not shown). A rotational speed detector 14 for detecting the rotational speed Nt of the output shaft and a vehicle speed detector 15 for detecting the rotational speed of the output shaft of the transmission 3, that is, the vehicle speed v are connected. The controller 10 includes a forward / reverse changeover switch 17 for instructing forward / reverse travel of the vehicle, a shift switch 18 for instructing a maximum speed stage between the first speed to the fourth speed, the engine speed sensor 25 and the bucket height detection described above. The sensor 26 is connected to a manual / automatic transmission means switching device 27 for switching whether the transmission 3 is automatically or manually shifted.

  The controller 10 controls the rotation speed (the number of rotations) of the engine 1 according to the operation amount of the accelerator pedal 11. Further, as described above, the controller 10 responds to the height of the bucket 112 calculated based on the rotational speed of the engine 1 detected by the engine rotational speed sensor 25 and the detection value of the bucket height detection sensor 26. To change each shift-permitted vehicle speed. Further, as will be described later, the controller 10 prohibits the upshifting in the transmission 3 by not outputting the upshifting signal to the transmission control device 20.

  FIG. 5 is a diagram showing V-shape loading, which is one method for loading earth and sand into a dump truck. In the V shape loading, first, the wheel loader 100 is moved forward as shown by an arrow a to scoop soil and the like, and then the wheel loader 100 is once moved backward as shown by an arrow b. Then, the wheel loader 100 is advanced toward the dump truck as indicated by an arrow c, and the scooped earth and sand is loaded on the dump truck, and the wheel loader 100 is moved back to the original position as indicated by an arrow d. .

  A description will be given of how the speed stage of the transmission 3 changes in the conventional wheel loader 100 when the earth and sand are loaded on the dump truck indicated by the arrow c in FIG. 5 with reference to FIG. When loading earth and sand on the dump truck, the wheel loader 100 is advanced toward the dump truck while raising the bucket 112. The speed stage when starting to advance toward the dump truck (at the start) is the first speed or the second speed. If the amount of depression of the accelerator pedal 11 is small and the rotational speed of the engine 1 is low, the shift permission vehicle speed v23 decreases as described above. Therefore, the vehicle speed reaches the shift permission vehicle speed v23 before the bucket 112 is raised to the height required for loading on the dump truck, and the speed is shifted up from the second speed to the third speed.

  Since the vehicle speed further increases due to this shift-up, the wheel loader 100 may reach the dump truck before the bucket 112 is raised to a height necessary for loading on the dump truck. In this case, the operator of the wheel loader 100 must apply a brake to stop the wheel loader 100 and raise the bucket 112. Therefore, not only the work efficiency is lowered, but also the operator of the wheel loader 100 feels bothersome.

  As a prior art, there is known a transmission configured to maintain the speed stage at that time when the height of the bucket 112 is equal to or higher than a set height. However, even if the transmission is used for the wheel loader 100, as shown in FIG. 6, before the bucket 112 reaches the set height, the vehicle speed reaches the shift permission vehicle speed v23 and is shifted up from the second speed to the third speed. If it does, the malfunction mentioned above cannot be eliminated. Further, if the set height is lowered, another problem of being held at a speed stage different from the operator's intention at the time of excavation work or high-speed running where the bucket 112 is at a low height position is caused. .

  On the other hand, in the wheel loader 100 of the present embodiment, the speed stage of the transmission 3 changes as follows when the earth and sand or the like indicated by the arrow c in FIG. 5 is loaded on the dump truck. Hereinafter, a description will be given with reference to FIG. In the wheel loader 100 of the present embodiment, as described above, when the height of the bucket 112 exceeds the first set height, the shift permission speeds v23 and v34 are changed to the shift permission speeds v23a and v34a shown in FIG. It is rising. Further, when the height of the bucket 112 exceeds the second set height, the upshift from the second speed to the third speed and the upshift from the third speed to the fourth speed are prohibited.

  As described above, since the first set height is set to the height of the bucket 112 when the lower end of the bucket 112 is positioned near the lowest ground height of the wheel loader 100, the wheel loader 100 moves forward toward the dump truck. As the bucket 112 begins to rise, the bucket 112 immediately reaches the first set height. When the height of the bucket 112 exceeds the first set height, the shift permission speed v23 rises to v23a, so the timing of upshifting from the second speed to the third speed is delayed compared to the conventional wheel loader 100, and the shift is performed. Increase in vehicle speed due to up can be suppressed. That is, as soon as the wheel loader 100 starts to move forward toward the dump truck, the timing for shifting up from the second speed to the third speed is delayed as compared with the conventional wheel loader 100. Also, if the bucket 112 exceeds the second set height, the upshift from the 2nd speed to the 3rd speed is prohibited, so the upshift is performed before the bucket 112 is raised to the height required for loading onto the dump truck. It is possible to prevent the problem that the wheel loader 100 reaches the dump truck due to the speed increase due to the above.

--- Flow chart ---
FIG. 8 is a flowchart showing the operation of the shift control process of the transmission 3 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 processing shown in FIG. 8 is started and repeatedly executed by the controller 10. In step S1, the engine speed detected by the engine speed sensor 25 is read, and the process proceeds to step S3. In step S3, each shift permission speed is changed and set as shown in FIG. 4 according to the rotational speed of the engine 1 read in step S1, and the process proceeds to step S5.

  In step S5, the height of the bucket 112 is calculated based on the detection value of the bucket height detection sensor 26, and the process proceeds to step S7. In step S7, it is determined whether or not the height of the bucket 112 calculated in step S5 exceeds the first set height. If an affirmative determination is made in step S7, the process proceeds to step 9, the shift permission speeds v23, v34 are changed to the above-described shift permission speeds v23a, v34a, and the process proceeds to step S11. In step S11, it is determined whether or not the height of the bucket 112 calculated in step S5 exceeds the second set height. If an affirmative determination is made in step S11, the process proceeds to step 13, where the speed stage currently selected in the transmission 3 is the second speed or the third speed based on the information on the speed stage selection state output from the transmission control device 20 Determine whether or not.

  If an affirmative determination is made in step S13, that is, if the speed stage of the transmission 3 is 2nd speed or 3rd speed, setting is made so as to prohibit upshifting, and the routine proceeds to step S17. In step S17, a well-known shift control calculation is performed based on each shift permission speed set in step S3, and if a shift is necessary, a control signal instructing upshift or downshift is output to the transmission control device 20. And return. In step S17, if step S9 is executed, a shift control calculation reflecting the execution result is performed. Thereby, as described above, it is difficult to shift up from the second speed to the third speed and from the third speed to the fourth speed. In step S17, if step S15 is executed, a shift control calculation reflecting the execution result is performed. Thereby, the upshift from the 2nd speed to the 3rd speed and the upshift from the 3rd speed to the 4th speed are prohibited.

  If any of steps S7, S11, and S13 is negatively determined, the process proceeds to step S17.

According to the present embodiment, the following operational effects can be achieved.
(1) When the height of the bucket 112 exceeds the first set height, the shift permission speed is increased to make it difficult for the shift up to occur. Thus, for example, even in a state where the accelerator pedal 11 is not largely depressed during V-shape loading, a shift up contrary to the operator's intention due to a decrease in the shift permission speed and an increase in the speed of the wheel loader 100 due to the shift up are achieved. Can be suppressed. Therefore, it is possible to prevent a problem that the wheel loader 100 reaches the dump truck before the bucket 112 rises to a height necessary for loading into the dump truck, and it is possible to prevent a reduction in work efficiency.

(2) When the height of the bucket 112 exceeds the first set height, the transmission 3 provided from the first speed stage to the fourth speed stage is unlikely to shift up from the second speed to the third speed. did. Thus, for example, the shift-up contrary to the operator's intention can be effectively suppressed during the second speed traveling frequently used when approaching the dump truck of V-shape loading, so that the above-described problems can be effectively prevented.

(3) Pitching of the wheel loader 100 is induced by speed increase due to upshifting or deceleration by braking to suppress this speed increase, but when the height of the bucket 112 is high, this pitching increases and the wheel The loader 100 tends to become unstable. However, in the wheel loader 100 of the present embodiment, when the height of the bucket 112 exceeds the second set height, the upshift from the second speed to the third speed and the upshift from the third speed to the fourth speed are prohibited. Configured to do. Therefore, for example, when approaching the dump truck with V-shape loading, it is possible to prohibit a shift-up that is against the operator's intention until the wheel loader 100 approaches the dump truck. Thereby, the malfunction by the pitching mentioned above can be prevented.

---- Modified example ---
(1) In the above description, the number of selectable speed stages in the transmission 3 is 4. However, the present invention is not limited to this, and may be 3 stages or 5 stages or more. When the number of speed stages that can be selected in the transmission 3 is other than 4, for example, when the speed stage that is frequently used when approaching the dump truck is other than 2nd speed, What is necessary is just to be able to suppress the shift up contrary to the intention.

(2) In the above description, the wheel loader 100 has been described as an example of the work vehicle. However, the present invention is not limited to this, and may be another work vehicle such as a forklift.

(3) In the above description, the shift permission speeds v23a and v34a are, for example, about 10% higher than the maximum values of the shift permission speeds v23 and v34 that change according to the rotational speed of the engine 1, for example. Although set, the present invention is not limited to this. For example, the shift permission speed v23a may be set to approximately the middle between the maximum value of the shift permission speed v23 that changes according to the rotational speed of the engine 1 and the maximum vehicle speed V2 (see FIG. 4) at the second speed. Similarly, for example, the shift permission speed v34a is set to approximately the middle between the maximum value of the shift permission speed v34 that changes according to the rotational speed of the engine 1 and the maximum vehicle speed V3 (see FIG. 4) at the third speed. Also good.
(4) You may combine each embodiment and modification which were mentioned above, respectively.

  The present invention is not limited to the above-described embodiment, and the vehicle speed detecting means for detecting the vehicle speed, the engine rotational speed detecting means for detecting the rotational speed of the engine, and the transmission speed stage are shifted up and shifted. Downshifting means, shifting control means for allowing upshifting by the shifting means when the vehicle speed detected by the vehicle speed detecting means is equal to or higher than the upshifting vehicle speed, and the working equipment height for detecting the height position of the working equipment. A shift-up-permitted vehicle speed changing unit that raises a shift-up-permitted vehicle speed when the height position of the work machine device detected by the position detection unit and the work machine device height position detection unit is equal to or higher than the first set value. And a shift control device having various structures.

DESCRIPTION OF SYMBOLS 1 Engine 3 Transmission 10 Controller 11 Accelerator pedal 15 Vehicle speed detector 20 Transmission control device 25 Engine speed sensor 26 Bucket height detection sensor 100 Wheel loader 111 Arm 112 Bucket

Claims (3)

Vehicle speed detection means for detecting the vehicle speed;
Engine rotation speed detection means for detecting the rotation speed of the engine;
Transmission means for shifting up and down the transmission speed stage;
Shift control means for permitting upshift by the shift means when the vehicle speed detected by the vehicle speed detection means is equal to or higher than the upshift permission vehicle speed;
A work implement device height position detecting means for detecting the height position of the work implement device;
Shift-up-permitted vehicle speed changing means for raising the shift-up-permitted vehicle speed when the height position of the work machine device detected by the work machine device height position detecting unit is equal to or higher than a first set value. A shift control apparatus for an industrial vehicle. In the industrial vehicle shift control device according to claim 1,
The speed stage of the transmission is 3 speeds or more,
The shift control device for an industrial vehicle, wherein the shift-up permission vehicle speed is a threshold value when the shift control unit permits a shift-up from the second speed to the third speed of the transmission speed stage. In the industrial vehicle shift control device according to claim 1,
The shift control means, when the height position of the work implement apparatus detected by the work implement apparatus height position detection means is equal to or higher than a second set value higher than the first set value, A shift control apparatus for an industrial vehicle, which prohibits upshifting by a shift means.

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