JP2006336390A - Method and device for detecting load of working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the load of a working vehicle with higher accuracy. <P>SOLUTION: A load detector is provided for detecting the load of a cargo work object held in a bucket by vertically moving a working boom having the bucket by a boom cylinder. A load detecting controller 21 for computing the load of the cargo work object and displaying it on a display device, forms beforehand a reference map based on the reference load of the cargo work object and the differential pressure of hydraulic detectors 11A, 11B on the rod side and tail side of the boom cylinder, corresponding to the turning angle of the working boom, from the detection values of the hydraulic detectors 11A, 11B and a boom position detector 12 for detecting the turning angle of the working boom, further forms a plurality of correction maps with correction values obtained by an engine speed detector 14 and a vehicle speed detector 15, added to the reference map, and computes the load based on the correction map selected according to the detection values of the hydraulic detectors 11A, 11B, boom position detector 12, engine speed detector 14 and vehicle speed detector 15. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention detects the weight (load) of a cargo handled by the bucket in a cargo handling operation in which a bucket is driven by a work vehicle such as a wheel loader and a cargo handling material such as earth and sand is loaded via a work arm. The present invention relates to a load detection method and apparatus for a working vehicle.

An example of a conventional load detection device is disclosed in Patent Document 1.
In Patent Document 1, the load correction unit at the time of no load of the bucket is obtained by subtracting the pressure detected by the rod pressure detection unit from the pressure detected by the tail pressure detection unit of the boom cylinder by the no load load correction unit in the control unit. The speed correction means calculates the boom speed by dividing the difference between the position detection signal of the position detector at the start of load detection and the position detection signal at the end of load detection by the measurement time, and corrects the load accordingly. The position change correction means corrects the detected load that changes depending on the position of the boom by the position signal of the position detector.
No. 6-736

  However, for example, when loading on a dump truck for transportation, the load amount is regulated on the road, and it is necessary to know the transportation amount accurately, so load detection can detect the loading amount with higher accuracy. A device is sought.

  An object of the present invention is to provide a load detection method and apparatus for a work vehicle that can detect a load with higher accuracy even in an arbitrary operation state.

  According to a first aspect of the present invention, there is provided a load detection method for a work vehicle, wherein a boom cylinder driven by hydraulic pressure supplied from a hydraulic pump is provided on a vehicle main body, a work boom rotated up and down by the boom cylinder, and a work boom. When detecting the load of the cargo handling object held by the cargo handling equipment during the cargo handling work of the working vehicle provided with the cargo handling equipment provided at the tip side of the hydraulic pressure of the tail side oil chamber of the boom cylinder and the rod side Detection of the oil pressure in the oil chamber, the tilt angle of the work boom, the rotation speed of the work boom, the rotational speed of the engine, and the traveling speed of the vehicle body, and detection by the tail side hydraulic pressure detector formed in advance. The relationship between the reference load of the cargo item selected based on the value, the differential pressure between the detected values of the tail-side oil pressure detector and the rod-side oil pressure detector, and the detected value of the boom position detector of the work boom is shown. Standard In addition, a plurality of correction maps to which correction data based on the rotation speed of the work boom, the number of revolutions of the engine, and the traveling speed of the vehicle main body are added are formed, and the selected map is selected based on each detection value. The load is calculated based on the correction map.

  A load detecting device for a working vehicle according to claim 2, wherein a boom cylinder driven by hydraulic pressure supplied from a hydraulic pump, a working boom rotated up and down by the boom cylinder, and a working boom are provided on the vehicle body. A load detecting device for a working vehicle for detecting a load of a load held by the load handling equipment, comprising: a hydraulic pressure of a tail side oil chamber of the boom cylinder; Tail-side oil pressure detector and rod-side oil pressure detector that detect the oil pressure in the rod-side oil chamber, respectively, a boom position detector that detects the tilt angle of the work boom, and the number of revolutions of the engine that drives the hydraulic pump And a vehicle speed detector for detecting the traveling speed of the vehicle body, and calculates the load of the cargo item based on the detection value of each detector and displays it on the display device. A load detection controller is provided, and the load detection controller includes a reference load of a cargo item selected based on a detection value of the tail side oil pressure detector, and detection values of the tail side oil pressure detector and the rod side oil pressure detector. Correction data based on the rotation speed of the work boom, the number of revolutions of the engine, and the traveling speed of the vehicle body has been added to the reference map that represents the relationship between the differential pressure and the detection value of the boom position detector of the work boom. A plurality of correction maps are provided, a correction map is selected based on the detected value, and a load is calculated based on the correction map.

  According to the above configuration, the load obtained from the detected value of the boom cylinder tail side oil chamber is divided into a plurality of parts, and the boom cylinder tail side oil chamber corresponding to the angle of the work boom for each load section Create a reference map that shows the relationship between the pressure differentials in the rod-side oil chamber, and then create a correction map that adds correction data for boom rotation speed, engine speed, and vehicle speed to the reference map data. The load classification is selected based on the detected value of the tail side oil chamber, the correction map corresponding to the detected values of the rotation speed of the boom, the engine speed and the vehicle speed is selected, and the boom cylinder is selected based on the correction map. Since the load on the cargo handling object is calculated from the differential pressure in the oil chamber and the angle of the work boom, the oil pressure changes from the hydraulic pump to the boom cylinder due to the weight fluctuation of the cargo handling, the engine speed, and the vehicle speed. Can be effectively corrected to heavy fluctuations, it is possible to detect the load of the cargo material with higher accuracy.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Embodiment 1]
The present invention relates to a load detection device for a working vehicle such as a wheel loader.

  As shown in FIG. 1, a vehicle body 1 of a wheel loader has a pair of left and right front wheels 7F and a rear wheel 7R, and a work boom 3 is pivotable in a vertical direction on a support shaft 2 in the vehicle width direction at the front. It is supported by. The work boom 3 is driven by a boom cylinder 4, and a bucket 5 serving as a cargo handling tool is supported at the tip of the work boom 3 so as to be rotatable in the vertical direction via a horizontal shaft 5a. The bucket 5 is rotated up and down by a bucket rotating cylinder 6 via a link member 6a.

  The wheel loader includes a tail-side oil pressure detector 11A that detects the oil pressure in the tail-side oil chamber of the boom cylinder 4 and a rod-side oil chamber in order to detect the load of a cargo item such as earth and sand held in the bucket 5. A rod-side oil pressure detector 11B that detects the oil pressure of the working boom 3, a boom position detector 12 that detects the angular position of the work boom 3, and a bucket angle detector that detects the angle of the bucket 5 (or a proximity switch that detects backward tilt) 13), an engine speed detector 14 for detecting the rotational speed of the engine E that drives a hydraulic pump (not shown) for supplying hydraulic pressure to the boom cylinder 4, and the traveling speed of the wheel loader from the rotational speed of the front wheels 7F. A vehicle speed detector 15 for detecting (vehicle speed) is provided.

  Further, based on the detection values of the detectors 11A, 11B, 12, 14, and 15, a load detection controller 21 that calculates a load, a display device 22 that displays the calculated load value, and the load value are printed. A printer 23 or a memory card for recording a load value, and a cancel switch 24 for starting or restarting load detection are provided.

  As shown in FIG. 2, the display device 22 calculates the load value by the load detection controller 21 based on the detection values of the detectors 11A, 11B, 12, 13, 14, and 15, and performs one cargo handling operation. A load display unit 22a for displaying a load value detected, calculated and averaged a plurality of times, a loading number display unit 22b, and a cumulative load display unit 22c are provided.

  As shown in FIG. 3, the load detection controller 21 includes a differential pressure detection unit 31 that detects a differential pressure from detection values of the tail side hydraulic pressure detector 11A and the rod side hydraulic pressure detector 11B, and a tail side hydraulic pressure detector 11A. Based on the detected value, a load category selection unit 32 for selecting from preset load categories (can be arbitrarily set) [for example (0 or) small load: A, medium load: B, large load: C], and measurement The lifting speed of the work boom 3 is obtained from the detection values of the boom position detector 12 at the time of disclosure and at the end of measurement, and a boom lifting speed category set in advance [for example, high speed rising: Vu2, low speed rising: Vu1, stop: V0, low speed. A boom speed calculation / section selection unit 33 for selecting descent: Vd1, high speed descent: Vd2], and a rotation speed section set in advance based on the detection value of the engine speed detector 14 [for example, low speed idle rotation: Lo, N1 rotation: N1, N2 rotation: N21, high-speed idle rotation: NHi] and an engine rotation speed classification selection unit 34, and a speed classification set in advance based on the detection value of the vehicle speed detector 15 [for example, high-speed advance : H2, low speed forward: H1, stop: S, reverse: B], a vehicle speed category selection unit 35, a load calculation unit 30, and a load recording unit 36 are provided.

  In the load calculation unit 30, the reference differential pressure value in which the relationship between the differential pressure of the tail side hydraulic pressure detector 11A and the rod side hydraulic pressure detector 11B and the angle of the work boom 3 is expressed in advance for each of the load categories A to C. A reference map M1 represented by F0 to F2 is created. In the reference map M1, the lifting speed Vd2, Vd1, V0, Vu1, Vu2 of the work boom 3, the engine speeds NLo, N1, N21, NHi, the traveling speeds B, S, H1, Correction maps M <b> 2 to M <b> 4 in which correction data by H <b> 2 is added and the correction differential pressure value is expressed are created. Accordingly, a corresponding correction map M4 is selected based on each detected value, and a load value is calculated based on this correction map M4.

An initial data acquisition mode for creating the reference map M1 and the correction maps M2 to M4 will be described with reference to FIGS.
As shown in FIG. 7, the work boom 3 is raised from 0 ° to 90 °, and the differential pressure between the detected values of the tail-side hydraulic pressure detector 11A and the rod-side hydraulic pressure detector 11B of the boom cylinder 4 at this time is, for example, the boom Reference differential pressure values F0 to F2 are recorded every angle of the work boom 3 detected by the position detector 12, for example, every 3 °. At this time, a plurality of, for example, three load sections A to C are arbitrarily set as the load of the bucket 5, the reference differential pressure values F0 to F2 are represented for each of the load sections A to C, and the reference map M1 is created [ FIG. 4, FIG. 7 (a)].
Next, the work boom 3 is raised from 0 ° to 90 °, and the boom position detector 12 detects when the measurement is disclosed and at the end of the measurement, and the boom speed calculation / section selection unit 33 selects the work boom 3. A correction value for the differential pressure with respect to the boom angle is acquired for each of the lifting speeds Vd2, Vd1, V0, Vu1, and Vu2. Then, a correction map M2 showing corrected differential pressure values F0-1, F1-1, F2-1 obtained by adding correction data to the reference differential pressure values F0, F1, F2 is created for each load category [ FIG. 7 (b)].

  Similarly, for each engine speed NLo, N1, N21, NHi detected by the engine speed detector 14, a correction value for the differential pressure with respect to the boom angle is acquired, and the corrected differential pressure values F0-1, F1 are obtained. A correction map M3 representing corrected differential pressure values F0-2, F1-2, and F2-2 obtained by adding correction data to -1, F2-1 is created for each load segment and each speed segment [Fig. 7 (c)].

  Further, similarly, a corrected differential pressure value for the vehicle speed is acquired for each of the traveling speeds B, S, H1, and H2 of the vehicle body 1 detected by the vehicle speed detector 15, and corrected differential pressure values F0-2, F1-2, and F2. A correction map M4 representing corrected differential pressure values F0-3, F1-3, and F2-3 obtained by adding correction data to F2-2 is created for each load category, each speed category, and each engine speed category. [FIG. 7 (d)].

A load calculation method during operation will be described with reference to FIG.
According to the reference map M1, [actually selected correction map M4 is used, but will be described using the reference map M1 for convenience here] In the load sections A to C, equations (1) to (3) respectively. Is used to calculate the load values W1 to W3.

A) For load classification A,
W1 = F1 / (P2-P1) × (PD1-P1) (1 formula)
Here, PD1: detected differential pressure value, P1: differential pressure value of F0 on the boom angle α,
P2: F2 reference differential pressure value on the boom angle α.

B) For load classification B,
W2 = [F1 + (F2-F1)] / (P3-P2) × (PD2-P2) (2 formulas)
Here, PD2: detected differential pressure value, P2: differential pressure value of F2 on the boom angle α,
P3: Reference differential pressure value of F3 on the boom angle α.

C) For load category C:
W3 = [F2 + (F2-F1)] / (P3-P2) × (PD3-P3) (3 formulas)
Here, PD2 is a detected differential pressure value, P2 is a differential pressure value of F2 on the boom angle α, and P3 is a reference differential pressure value of F3 on the boom angle α.

Next, the load detection procedure in the above configuration will be described with reference to FIG.
1) When the bucket angle detector 13 confirms that the bucket 5 is tilted backward (STEP 1), the boom position detector 12 detects the position of the work boom 3 at the start of detection (STEP 2).

  2) The rod side oil pressure detector 11B detects the oil pressure in the rod side oil chamber of the boom cylinder 4 (STEP 3), and the tail side oil pressure detector 11A detects the oil pressure in the rod side oil chamber of the boom cylinder 4 (STEP 4). ).

3) The engine speed detector 14 detects the engine speed (STEP 5), and the vehicle speed detector 15 detects the vehicle speed (traveling speed) of the vehicle body 1 (STEP 6).
4) The position of the work boom 3 at the end of detection is detected by the boom position detector 12 (STEP 7).

  5) The boom speed calculation / section selection unit 33 calculates the boom speed from the position (angle) of the work boom 3 at the start of detection and at the end of detection, and selects the boom speed section. Then, the correction map M4 corresponding to the load category data by the load category selector 32, the engine speed category data by the engine speed category selector 33, and the boom speed category data by the boom speed category selector 34 is selected. (STEP8). Then, the load value is calculated based on the selected correction map M4 (STEP 9).

  6) The actual measured load shows a value that is greater than the actual load immediately after holding, and when the time elapses, it becomes smaller than the actual load and then approaches the actual load. Sampling is performed several times until the calculated value becomes larger than the calculated value, and sampling is performed until the difference between the previous calculated value and the current calculated value becomes the smallest (STEP10,11). Are averaged (STEP 12) and displayed on the load display section 22a of the display device 22 (STEP 13). Further, it is recorded in the load recording unit 36 (STEP 14). These measured values are printed by the printer 23 or recorded on a memory card which is a recording medium.

  In the above loading / unloading work, when the cargo handling material is loaded in the bucket 5 or more than specified, or when the operator determines that the load value displayed on the load display portion 22a is clearly erroneous measurement, the cancel switch 24 is pressed. The calculated value is canceled and the process moves to remeasurement.

  According to the above configuration, the oil pressure in the tail side oil chamber of the boom cylinder 4 is detected by the tail side oil pressure detector 11A, and the load of the cargo handling object held in the bucket 5 is detected by the load detection controller 21 in a plurality of load categories. Since the calculation is performed by selecting from A to C, the measurement accuracy can be further improved.

  Further, in addition to the angular position and rotation speed of the work boom 3, a correction map M4 that corrects the reference value in accordance with the rotational speed of the engine E and corrects the reference value in accordance with the moving speed of the vehicle body 1. Therefore, even if the discharge hydraulic pressure of the hydraulic pump fluctuates depending on the rotation speed of the engine E, the load value can be calculated with high accuracy. Further, even when the vehicle body 1 is in a stopped state, a forward movement at a high speed or a low speed, or a reverse movement, the accuracy of the load value does not decrease.

  Therefore, it is possible to detect the load of the cargo handling object such as earth and sand held by the bucket 5 with higher accuracy than in the past in any work state.

It is a block diagram which shows embodiment of the load detection apparatus of the working vehicle which concerns on this invention. It is a front view which shows the display apparatus of the load detection apparatus. It is a block diagram which shows the load detection controller of the load detection apparatus. It is a figure which shows the reference | standard map produced in the load calculating part of the load detection controller. It is explanatory drawing explaining the calculation formula of the load based on the map. It is explanatory drawing of the data acquisition procedure which produces the same reference map and correction map. (A)-(d) is explanatory drawing which shows a part of correction | amendment map. It is a flowchart explaining the measurement operation | movement of the load detection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle main body 2 Support shaft 3 Working boom 4 Boom cylinder 5 Bucket 5a Horizontal shaft 6 Bucket rotation cylinder 7F Front wheel 7R Rear wheel 11A Tail side oil pressure detector 11B Rod side oil pressure detector 12 Boom position detector 13 Bucket angle detector 14 Engine speed detector 15 Vehicle speed detector 21 Load detection controller 22 Display device 23 Printer 24 Cancel switch 30 Load calculation unit

Claims (2)

A work provided with a boom cylinder driven by hydraulic pressure supplied from a hydraulic pump, a work boom rotated in the vertical direction by the boom cylinder, and a cargo handling device provided on the front end side of the work boom. When detecting the load of the cargo handling object held by the cargo handling equipment during the cargo handling operation of the vehicle,
The hydraulic pressure of the tail side oil chamber and the rod side oil chamber of the boom cylinder, the inclination angle of the work boom, the rotation speed of the work boom, the engine speed, and the traveling speed of the vehicle body are detected. ,
The reference load of the cargo item selected based on the detection value of the tail side hydraulic detector formed in advance, the differential pressure between the detection values of the tail side hydraulic detector and the rod side hydraulic detector, and the boom of the work boom A plurality of correction maps in which correction data based on the rotation speed of the work boom, the rotation speed of the engine, and the traveling speed of the vehicle body are further added to the reference map that represents the relationship with the detection values of the position detector. A load detection method for a working vehicle that calculates a load based on the correction map selected based on the detection values. The vehicle main body includes a boom cylinder driven by hydraulic pressure supplied from a hydraulic pump, a work boom that is turned up and down by the boom cylinder, and a cargo handling tool provided on the front end side of the work boom, A load detection device for a working vehicle for detecting a load of a cargo handling object held by the cargo handling equipment,
A tail side oil pressure detector and a rod side oil pressure detector for detecting the oil pressure of the tail side oil chamber of the boom cylinder and the oil pressure of the rod side oil chamber, respectively;
A boom position detector for detecting an inclination angle of the work boom;
An engine speed detector for detecting the engine speed for driving the hydraulic pump;
A vehicle speed detector for detecting the traveling speed of the vehicle body,
A load detection controller for calculating the load of the cargo handling object based on the detection value of each detector and displaying it on the display device is provided.
The load detection controller includes a reference load of a cargo item selected based on a detection value of the tail side hydraulic pressure detector, a differential pressure between detection values of the tail side hydraulic pressure detector and the rod side hydraulic pressure detector, and a work boom. A reference map that represents the relationship between the detected value of the boom position detector and a plurality of correction maps to which correction data based on the rotation speed of the work boom, the engine speed, and the traveling speed of the vehicle body is added. A load detection device for a working vehicle configured to select a correction map based on the detected value and calculate a load based on the correction map.

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