JP2021050653A - Crawler-type working machine - Google Patents

Abstract

To obtain a crawler-type working machine which can improve fuel economy, can reduce noise, and is favorable in operability.SOLUTION: A crawler-type working machine 1 comprises: a traveling hydraulic motor 30 driven by pressure oil from a traveling hydraulic pump 26 which is driven by an engine 24; a traveling pilot pressure generator 32 for generating traveling pilot pressure on the basis of an operation amount of a traveling lever; a pressure sensor 34 for detecting a pressure value of the traveling pilot pressure; an ECU 42 for calculating a load rate of the engine 24 and controlling a rotation number of the engine; and a control device 40. In the case that a high-speed area for determining on the basis of the traveling pilot pressure is in an off-state when the load rate is in a low-load state, the control device 40 imposes a first limit on a maximum rotation number of the engine 24, sets an upper limit of a rotation number on a relatively-low first maximum rotation number, releases the first limit on the maximum rotation number of the engine 24 when the high-speed area is in an on-state, and sets an upper limit of a rotation number on a relatively-high speed second maximum rotation number.SELECTED DRAWING: Figure 2

Description

The present invention relates to a crawler type work vehicle that travels by a pair of crawlers provided on the left and right sides of the vehicle body.

A crawler type carrier is known as an example of a work vehicle traveling by a crawler (see Patent Document 1: Japanese Patent Application Laid-Open No. 8-244651). As an example, such a crawler type carrier is provided with a cockpit in which an operator rides and operates in the front part (for example, the left side part) of the vehicle body, and travels in the front part (for example, the right side part) of the vehicle body. An engine room is provided in which an engine for driving a device or the like is housed. On the other hand, a vessel (loading platform) for loading earth and sand is provided at the rear of the vehicle body so that it can be flipped up. When traveling, the direction of travel can be changed by making the operating speeds of the left and right crawlers different.

Japanese Unexamined Patent Publication No. 8-244651

Here, in the conventional crawler type work vehicle as exemplified in Patent Document 1, the engine speed increases even when the traveling lever is slightly operated to travel at a low speed. It was. Therefore, not only the fuel efficiency performance is deteriorated and the noise is increased, but also the operability is deteriorated.

The present invention has been made in view of the above circumstances, and realizes a crawler type work vehicle capable of improving fuel efficiency and reducing noise, particularly at low speeds, and preventing deterioration of operability. The purpose is.

The present invention solves the above problems by means of solutions as described below.

The crawler type work vehicle according to the present invention includes an engine, a traveling hydraulic pump and a pilot hydraulic pump driven by the engine, a traveling hydraulic motor driven by pressure oil supplied from the traveling hydraulic pump, and a vehicle body. A pair of crawlers provided on the left and right and driven by the traveling hydraulic motor, and a traveling pilot pressure generating device that generates traveling pilot pressure by pressure oil supplied from the pilot hydraulic pump based on the amount of operation of the traveling lever. A pressure sensor for detecting the pressure value of the traveling pilot pressure and a control device for performing drive control including calculation of the load factor of the engine and rotation speed control are provided, and the traveling hydraulic motors are provided on the left and right crawler respectively. A corresponding first traveling hydraulic motor and a second traveling hydraulic motor are provided, and as the traveling pilot pressure, a first traveling pilot pressure for controlling the first traveling hydraulic motor and the second traveling hydraulic pressure are provided. A second traveling pilot pressure for controlling the motor is generated, and the control device acquires the pressure value of the first traveling pilot pressure and the pressure value of the second traveling pilot pressure after the engine is started. When the vehicle is in a straight-ahead state in which the difference between the pressure value of the first traveling pilot pressure and the pressure value of the second traveling pilot pressure is within a predetermined range, the pressure value of the first traveling pilot pressure or the pressure value of the second traveling pilot pressure When at least one of the pressure values does not rise above the predetermined first pressure value, the high speed range is OFF, and both the pressure value of the first traveling pilot pressure and the pressure value of the second traveling pilot pressure are the predetermined first pressure. When it rises above the value, it is determined that the high speed range is ON, and when the load factor of the engine does not rise above the predetermined first load factor, it is in a low load state, and the load factor of the engine is predetermined. When the load factor is higher than the first load factor, it is determined that the load factor is high, and when the load factor is low and the high speed range is OFF, the first limit of the maximum engine speed is set. By imposing, the upper limit of the rotation speed is set to the first maximum rotation speed which is set relatively low as the allowable rotation speed, and when the high speed range is ON, the first limit of the maximum rotation speed of the engine is set. Is released, and it is a requirement to control to set the upper limit of the rotation speed to the second maximum rotation speed which is set relatively high as the allowable rotation speed.

According to the crawler type work vehicle according to the present invention, it is possible to improve fuel efficiency and reduce noise, and prevent deterioration of operability, particularly at low speeds.

It is a perspective view which shows the example of the crawler type work vehicle which concerns on embodiment of this invention. It is the schematic of the hydraulic circuit system of the crawler type work vehicle shown in FIG. It is a flowchart which concerns on the engine speed control of the crawler type work vehicle shown in FIG. It is explanatory drawing of the engine rotation speed in the engine rotation speed control of the crawler type work vehicle shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view (a perspective view from above the rear portion) showing an example of the crawler type work vehicle 1 according to the present embodiment. Further, in all the drawings for explaining the embodiment, members having the same function may be designated by the same reference numerals, and the repeated description thereof may be omitted.

First, the overall configuration of the crawler type work vehicle 1 (hereinafter, may be simply referred to as "vehicle") will be described. Here, the crawler type carrier will be described as an example of the crawler type work vehicle 1 according to the present embodiment, but the present invention is not limited thereto.

As shown in FIG. 1, the crawler type work vehicle 1 is provided with a traveling device 12 having a pair of left and right crawlers (endless crawler belts) 22 at the lower part of the vehicle body 10. Further, in the front portion (for example, the left portion) of the vehicle body 10, a closed type (or open type) cockpit 16 is provided in which an operator (operator) rides and operates. Further, an engine room 20 in which an engine 24 or the like for driving a traveling device or the like is housed is provided in the front portion (for example, the right side portion) of the vehicle body 10. As an example, a water-cooled diesel engine is used as the engine. On the other hand, a vessel 14 for loading earth and sand or the like is provided at the rear portion of the vehicle body 10 so as to be able to flip up. A traveling lever for operating the traveling by the operator, an operating lever for operating the vessel 14, and an accelerator pedal for adjusting the throttle opening of the engine are arranged in the cockpit 16 (all not shown). ..

Subsequently, FIG. 2 shows a schematic view of the hydraulic circuit system of the crawler type work vehicle 1 according to the present embodiment. As an example, the crawler type work vehicle 1 is configured to travel with an HST (Hydraulic Static Transmission). More specifically, the traveling is driven by the variable displacement traveling hydraulic pumps 26 (26A, 26B) and the pilot hydraulic pumps 28 driven by the engine 24, and the pressure oil supplied from the traveling hydraulic pumps 26 (26A, 26B). It includes a hydraulic motor 30 (30A, 30B) and a traveling pilot pressure generating device 32 that generates a traveling pilot pressure by the pressure oil supplied from the pilot hydraulic pump 28 based on the operation amount of the traveling lever. That is, the crawler 22 is driven by the traveling hydraulic motor 30 (30A, 30B) driven by the pressure oil supplied from the traveling hydraulic pump 26 (26A, 26B).

Further, a pressure sensor 34 (34FL, 34RL, 34FR, 34RR) that detects the pressure value of the traveling pilot pressure and outputs the pressure value to the control device 40, and a control device 40 that controls the drive of the entire crawler type work vehicle 1 are controlled. It includes an engine control unit (ECU) 42 that controls the engine 24 based on a command from the device 40. In the present embodiment, the control device 40 is configured to calculate the load factor of the engine 24 and control the rotation speed (command the rotation speed to the ECU 42).

Further, the remote control valve 38 (38A) that controls the direction and flow rate of the pressure oil supplied from the traveling hydraulic pump 26 (26A, 26B) to the traveling hydraulic motor 30 (30A, 30B) via the oil passage 36 (36A, 36B). , 38B), the remote control valves 38 (38A, 38B), and a signal control valve (not shown) for controlling each control pressure related to driving other mechanisms of the hydraulic circuit system. The traveling pilot pressure is set (adjusted) by opening and closing the remote control valves 38 (38A, 38B) by operating the traveling lever by the operator.

With such a configuration, the traveling pilot pressure is set by the operator operating the traveling lever, and the traveling hydraulic pump 26 (26A, 26B) whose output is variable according to the pressure is the traveling hydraulic motor 30 (30A, 30B). The crawler 22 is operated by driving the vehicle to run or turn the vehicle. Since the hydraulic mechanism and the like that operate the vessel 14 are the same as those of a known vehicle, detailed description thereof will be omitted.

Here, in the present embodiment, as the traveling hydraulic motor 30, the first traveling hydraulic motor 30A corresponding to one (for example, left) crawler and the second traveling hydraulic motor corresponding to the other (for example, right) crawler. Two of 30B are provided. Therefore, as the traveling pilot pressure, the first traveling pilot pressure for controlling the first traveling hydraulic motor 30A and the second traveling pilot pressure for controlling the second traveling hydraulic motor 30B are generated. ..

As described above, the pressure sensor 34 has a configuration in which it detects the pressure value of the traveling pilot pressure that increases or decreases according to the operation amount of the traveling lever and outputs it as a signal to the control device 40. In the present embodiment, as the pressure sensor 34, the first forward sensor 34FL and the first traveling hydraulic motor that detect and output the pressure value of the first traveling pilot pressure when the first traveling hydraulic motor 30A rotates in the forward direction. It is equipped with a first reverse sensor 34RL that detects and outputs the pressure value of the first traveling pilot pressure when the 30A rotates in the reverse direction. Further, the second forward sensor 34FR that detects and outputs the pressure value of the second traveling pilot pressure when the second traveling hydraulic motor 30B rotates in the forward direction, and the second traveling hydraulic motor 30B when the second traveling hydraulic motor 30B rotates in the backward direction. It is equipped with a second reverse sensor 34RR that detects and outputs the pressure value of the two traveling pilot pressures.

With such a configuration, the control method unique to the present embodiment, which will be described in detail below, can be realized, so that the above-mentioned problems can be solved. Here, FIG. 3 is a flowchart showing the processing contents related to the engine speed control in the crawler type work vehicle 1 according to the present embodiment. Further, FIG. 4 is a diagram for explaining the engine speed in the control.

As an outline of the engine rotation speed control performed by the control device 40 according to the present embodiment, first, the control device 40 has the above-mentioned pressure sensors 34 (first forward sensor 34FL, first reverse sensor 34RL, second forward sensor 34FR, The step of acquiring the pressure value detected and output by the second reverse sensor 34RR) is performed (step S1).

Next, the control device 40 carries out a step of determining whether or not the crawler type work vehicle 1 is in a straight-ahead state with respect to the traveling state (step S2). As an example, when the pressure value of the first traveling pilot pressure and the pressure value of the second traveling pilot pressure detected by the pressure sensor 34 both receive a traveling command by operating the traveling lever, the difference between the two pressure values is When it is within the predetermined range, it is determined that the vehicle is traveling straight. In step S2, when it is determined that the vehicle is in a straight-ahead state, step S3 described later is carried out, and when it is determined that the vehicle is not in a straight-ahead state, step S4 described later is carried out. Incidentally, as a state in which the vehicle is not in a straight-ahead state, a vehicle turning state and a vehicle stopped state can be specifically mentioned.

Next, the control device 40 carries out a step of determining whether or not the traveling state of the crawler type work vehicle 1 is in the high speed range (step S3). More specifically, when at least one of the pressure value of the first traveling pilot pressure and the pressure value of the second traveling pilot pressure does not rise above the predetermined first pressure value after the engine 24 is started, the high speed range is OFF, and the first When both the pressure value of the 1st running pilot pressure and the pressure value of the 2nd running pilot pressure rise above the predetermined first pressure value, it is determined that the high speed range is ON. However, after it is determined that the high speed range is ON (in other words, in the state where the determination that the high speed range is ON is continued), the pressure value of the first running pilot pressure or the second running When at least one of the pressure values of the pilot pressure is lower than the predetermined second pressure value, it is determined that the high speed range is OFF. All of these judgments are based on the assumption that the vehicle is traveling straight.

That is, in the above-mentioned determination in the high-speed range, the ON determination is continued until the next OFF determination, and the OFF determination is continued until the next ON determination. The initial setting after starting the engine is an OFF determination.

Therefore, to explain with specific operations, for example, when starting traveling after starting the engine 24, when the traveling lever is operated from the start point side to the end point side and the operation amount based on the start point is smaller than a predetermined amount. In addition, it is determined that the high speed range is OFF. Further, when the traveling lever is operated from the start point side to the end point side and the operation amount based on the start point becomes larger than the predetermined amount (when the pressure increases from the above-mentioned first pressure value), the high speed range is ON. It is determined that there is. On the other hand, from the state in which the high-speed range is determined to be ON by starting the running and operating the running lever from the start point side to the end point side so that the operation amount of the start point reference is larger than the predetermined amount. When the traveling lever is operated from the end point side to the start point side and the operation amount becomes smaller than the predetermined amount (when the pressure value is lower than the above-mentioned second pressure value), it is determined that the high speed range is OFF. ..

In the present embodiment, the second pressure value is set to a value smaller than the first pressure value. As an example, the first pressure value is set to 1.8 [MPa] and the second pressure value is set to 1.5 [MPa], but the present invention is not limited thereto. According to this configuration, it is difficult to give the operator the impression that there is no feeling of running power, especially when the running lever is returned.

Next, in step S3, when it is determined that the high speed range is OFF, the control device 40 imposes the first limitation on the maximum rotation speed of the engine 24 and is set to a relatively low allowable rotation speed. A step of controlling the setting of the upper limit of the rotation speed to the first maximum rotation speed is performed (step S4). Therefore, even when the traveling lever is slightly operated to travel at a low speed, the rotation speed of the engine 24 does not increase, and the fuel efficiency performance can be improved and the noise can be reduced. In addition, it is possible to prevent deterioration of operability during low-speed traveling. Incidentally, the "upper limit" of the maximum rotation speed is set so as to reach when the throttle opening degree is 100 [%] (the same applies to step S5 described later).

On the other hand, when it is determined in step S3 that the high-speed range is ON, the control device 40 releases the first limitation on the maximum rotation speed of the engine 24 and calculates the load factor of the engine 24. In step S5, control is performed to set the upper limit of the rotation speed to the maximum rotation speed set as described below (step S5). More specifically, when the load factor of the engine 24 is in a low load state, the upper limit of the rotation speed is set to the second maximum rotation speed, which is set relatively higher than the first maximum rotation speed as the allowable rotation speed. Control to set. On the other hand, when the load factor of the engine 24 is in a high load state, the maximum rotation speed set within the range between the first maximum rotation speed and the second maximum rotation speed corresponding to the value of the load factor of the engine 24. Control is performed to set the upper limit of the number of rotations to the number (see FIG. 4). Therefore, when it is not appropriate to impose the first limit on the maximum number of revolutions of the engine 24, this can be released, and efficient work can be performed at the set maximum output.

It was set within the range between the first maximum rotation speed and the second maximum rotation speed corresponding to the above-mentioned "first maximum rotation speed", "second maximum rotation speed", and "engine load factor value". The "maximum rotation speed" is appropriately set based on the design strength of the traveling hydraulic pump 26 and the traveling hydraulic motor 30, the output characteristics of the engine 24, traveling, working performance, and the like. As an example, the first maximum rotation speed is set to 2330 [rpm] and the second maximum rotation speed is set to 2530 [rpm], but the present invention is not limited thereto. Further, the boundary value between the low load state and the high load state in the load factor of the engine 24 is set to 74 [%] as an example, but is not limited to this. The load factor of the engine 24 is calculated based on the fuel injection amount.

Next, the control device 40 acquires information on the throttle opening degree and determines the engine rotation speed according to the opening degree so as not to exceed the upper limit of the maximum rotation speed set in step S4 or S5 described above. , A step of outputting a rotation speed command to the ECU 42 is performed (step S6).

The above steps S1 to S6 are repeatedly executed until the power of the control device 40 is turned off due to the ignition key being turned off or the like.

As described above, in the conventional crawler type work vehicle, there is a problem in terms of engine speed control that may occur due to factors such as the use of a pressure switch for detecting the traveling pilot pressure. As an example, even when the vehicle travels at a low speed by slightly operating the travel lever, the control of the engine speed may be released, resulting in deterioration of fuel efficiency and increase in noise, and driving operation. It was making the sex worse. On the other hand, by applying the present invention, it becomes possible to solve the problem. That is, especially when the vehicle travels at a low speed, it is possible to improve the fuel efficiency performance and reduce the noise, and it is also possible to realize good traveling operability.

The present invention is not limited to the examples described above, and various modifications can be made without departing from the present invention. In particular, the crawler type carrier has been described as an example of the crawler type work vehicle, but the description is not limited to this, and the same applies to other crawler type work vehicles such as power shovels, for example. Needless to say, it can be applied.

1 Crawler type work vehicle 10 Body 12 Traveling device 14 Vessel 16 Control room 20 Engine room 22 Crawler 24 Engine 26, 26A, 26B Traveling hydraulic pump 28 Pilot hydraulic pump 30, 30A, 30B Traveling hydraulic motor 32 Traveling pilot pressure generator 34 , 34FL, 34FR, 34RL, 34RR Pressure sensor 38, 38A, 38B Remote control valve 40 Control device 42 Engine control unit (ECU)

Claims (5)

With the engine
The traveling hydraulic pump and the pilot hydraulic pump driven by the engine,
A traveling hydraulic motor driven by the pressure oil supplied from the traveling hydraulic pump and
A pair of crawlers provided on the left and right sides of the vehicle body and driven by the traveling hydraulic motor,
A traveling pilot pressure generating device that generates a traveling pilot pressure by the pressure oil supplied from the pilot hydraulic pump based on the operation amount of the traveling lever.
A pressure sensor that detects the pressure value of the traveling pilot pressure and
A control device for calculating the load factor of the engine and performing drive control including rotation speed control is provided.
As the traveling hydraulic motor, two are provided, a first traveling hydraulic motor and a second traveling hydraulic motor corresponding to the left and right crawlers, respectively.
As the traveling pilot pressure, a first traveling pilot pressure for controlling the first traveling hydraulic motor and a second traveling pilot pressure for controlling the second traveling hydraulic motor are generated.
The control device is
After starting the engine, the pressure value of the first traveling pilot pressure and the pressure value of the second traveling pilot pressure are acquired, and the pressure value of the first traveling pilot pressure and the pressure value of the second traveling pilot pressure are obtained. When the difference between the above is within a predetermined range and the vehicle is traveling straight, the high speed is obtained when at least one of the pressure value of the first traveling pilot pressure and the pressure value of the second traveling pilot pressure does not rise above the predetermined first pressure value. When the region is OFF and both the pressure value of the first traveling pilot pressure and the pressure value of the second traveling pilot pressure rise above the predetermined first pressure value, it is determined that the high speed region is ON, and the region is ON.
When the load factor of the engine does not increase from the predetermined first load factor, it is determined to be a low load state, and when the load factor of the engine rises from the predetermined first load factor, it is determined to be a high load state. ,
When the load factor is in a low load state,
When the high speed range is OFF, the first limit of the maximum engine speed is imposed, and the upper limit of the engine speed is set to the first maximum engine speed which is set relatively low as the allowable engine speed. ,
When the high-speed range is ON, the first limit on the maximum engine speed is released, and the upper limit of the engine speed is set to the second maximum engine speed, which is set relatively high as the permissible engine speed. A crawler type work vehicle characterized by performing control. The control device is
When the load factor is in a high load state,
When the high speed range is OFF, the first limit of the maximum engine speed is imposed, and the upper limit of the engine speed is set for the first maximum engine speed.
When the high speed range is ON, the first limitation of the maximum rotation speed of the engine is released, and the first maximum rotation speed and the second maximum rotation speed correspond to the value of the load factor of the engine. The crawler type work vehicle according to claim 1, wherein the upper limit of the rotation speed is set to the maximum rotation speed set within the range between. The control device is
After determining that the high-speed range is ON, when at least one of the pressure value of the first running pilot pressure or the pressure value of the second running pilot pressure is lower than the predetermined second pressure value, the high-speed range is set. The crawler type work vehicle according to claim 1 or 2, wherein it is determined to be OFF. The crawler type work vehicle according to claim 3, wherein the second pressure value is set to a value smaller than the first pressure value. The crawler type according to any one of claims 1 to 4, wherein the pressure sensor is configured to output a pressure value of the traveling pilot pressure that increases or decreases according to an operation amount of the traveling lever as a signal. Work vehicle.

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