JPH0638045B2 - Tilt control device for work equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a tilt control device for controlling a lateral tilt of a work machine connected to a tractor.

(Prior art and its problems) When a working device such as a rotary cultivator is connected to a tractor via a link device and used, the working device is always kept horizontal even if the tractor tilts in the lateral direction. In order to make it possible to detect the tilt of the working machine using the tilt sensor that detects the tilt in the lateral direction, the hydraulic cylinder provided on the lift rod of the tractor is expanded and contracted to correct the tilt. Horizontal control devices are known.

However, in this conventional main control device, since a pendulum type sensor in which a weight swings due to gravity is used as an inclination sensor, an error is likely to occur when the working machine tilts in the front-rear direction, and an accurate sensor is provided. It was difficult to perform horizontal control.

(Object of the Invention) An object of the present invention is to provide a tilt control device capable of more accurately performing tilt control of a working machine connected to a tractor.

(Structure of the Invention) A tilt control device for a working machine according to the present invention connects a working machine to a lift arm of a tractor via a link or a connecting arm, and a hydraulic cylinder between the lift arm and the link or the connecting arm. In the tilt control device for the working machine, wherein the tilting sensor for the working machine is hydraulically controlled based on the detection result of the tilting sensor for detecting the tilting in the lateral direction. Capacitance type sensors that hold the liquid between them and that electrically detect changes in the lateral capacitance that occur due to the flow of the liquid when tilting are used in parallel. It is characterized by eliminating the effect of the inclination of.

(Embodiment) FIG. 1 shows an embodiment of the present invention, in which a work machine (a rotary tiller in this embodiment) 2 is connected to a tractor 1 via a link device 3.

The link device 3 includes one top link 5 and a pair of left and right lower links 6, 6, and the top link 5 is a mast 7 of the work machine 2, and the lower links 6, 6 are left and right of the transmission case 9 of the work machine 2. Attached to the front ends of the connecting boards 10 provided on both sides. The middle portions of the lower links 6 and 6 are suspended from the hydraulic lift arm 13 of the tractor 1 by a pair of left and right lift rods 12 and 12 '. A hydraulic cylinder 15 is provided on one of the lift rods (a connecting arm when connecting a working machine with a two-point link device) 12,
The length of one lift rod can be freely adjusted by expanding and contracting this.

A tilt sensor 20 is attached to the upper part of the work machine 2. The inclination sensor 20 is a capacitance type inclination sensor as shown in FIGS. 2 and 3, and inside the case 21, three layers of electrode plates 23, 24, 25 are arranged at intervals. It is provided. Transparent plastic spacers 26, 26 'are interposed between the space between the three layers of electrodes 23, 24, 25, the front surface of the electrode plate 23 and the rear surface of the electrode plate 25. Circular liquid storage spaces 28, 28 'in front view are formed in the gaps between the electrode plates 23, 24, 25, and silicone oil 27 is filled therein to a depth of about half. The electrode plate 24 of the middle layer is formed by a pair of metal plates 24a and 24b arranged at intervals, and the electrode plates 23 and 25 of the front and rear layers are metal plates each having a vertical slit 29 in the central portion. It is configured. Therefore, in the tilt sensor 20, the first layer
Two capacitors on the front side composed of 23 and the second layer 24, that is, capacitors A and B composed of the electrode plates 23 and 24a, and two capacitors on the rear side composed of the second and third layers. That is, capacitors C and D each composed of the electrode plates 24b and 25 are provided respectively, and as a whole, two front and rear inclination sensors for detecting the inclination in the lateral direction are arranged in parallel. Then, these four capacitors A, B, C, D are connected to each other by a bridge circuit as shown in FIG. 4 (C), and the capacitance changes of these four capacitors A, B, C, D are bridged. The circuit measures the slope. That is, when the inclination sensor 20 is inclined (angle α) in the lateral direction (left-right direction in FIG. 2), one of the two capacitors A and C on the left side and the two capacitors B and D on the right side becomes low. Therefore, the amount of liquid on that side increases, and the capacitance on that side increases. On the contrary, the capacitance of the two capacitors on the front and rear sides, which are increased due to the inclination, decreases because the amount of liquid between the electrode plates decreases. Therefore, the magnitude of the inclination can be known by reading the voltage difference (V) on both sides with the bridge circuit.

Next, since the inclination sensor 20 is provided with two capacitors (A and C, B and D) in the front-rear direction as well, by incorporating them in the bridge circuit, the influence of the front-rear inclination is almost eliminated. It can be erased.

FIG. 5 shows the relationship between the inclination (θ) in the front-rear direction and the output voltage (V). According to the figure, even if there is an inclination of ± 45 degrees (θ) in the front-rear direction, It can be seen that only an error of about ± 1 degree occurs when converted. This is because, for example, when the tilt sensor 20 tilts forward, the front side capacitor A,
The liquid volume of B becomes large and the capacitance of the capacitor becomes larger than that of the capacitors C and D on the rear side. However, when considering the capacitors separately on the left and right sides, both sides have the same condition, so the influence is eliminated by the bridge circuit. This is because it can be done. In the conventional pendulum type tilt sensor, a considerable error was caused by tilting about 20 degrees in the front-rear direction.However, with this tilt sensor 20, even if the tilt in the front-rear direction is about 45 degrees, there is almost no output error. Much less of a problem.

As in the example shown in the figure, the lateral inclination can be detected by reading the capacitance change by forming one capacitor on each side instead of using four internal capacitors, but there is a longitudinal inclination. In this case, since the liquid surface is inclined, an error is likely to occur. Further, if there are only two capacitors, the dielectric constant changes when the temperature changes, so an error occurs in the detection result. However, if four capacitors are provided as in the illustrated example, they will be separated by opposing capacitors. Since the change in the dielectric constant is erased, an error is unlikely to occur.

If the viscosity of silicone oil is too high, the sensitivity will be poor,
If the viscosity is too low, it will be easily affected by vibration.
30 degrees is preferable.

FIG. 6 shows an example in which the tilt sensor 20 is attached to the tractor 1. The inclination sensor 20 may be installed on the tractor side as described above, or may be installed on the working machine side. FIG. 7 shows a block diagram of the tilt control device 40. This controller
40 is equipped with a manual tilt correction dial 41 that can set the tilt angle of the work machine.
The set value of 41 and the output of the tilt sensor 20 are compared to operate the solenoid SL of the valve for the hydraulic cylinder. As a result, the expansion and contraction of the hydraulic cylinder 15 is controlled, and the working machine can be placed in any tilted state.

FIG. 8 is a block diagram of the control device 40 ′ when performing total control of the tilt angle. The output of the tilt sensor 20, the output of the lift arm angle sensor 42 that detects the rotation angle of the lift arm 13, and the lift rod 12 are shown. Hydraulic cylinder 15 installed in
The output of the lift rod cylinder stroke sensor 43 for detecting the amount of expansion and contraction of the cylinder is supplied to the control box.
The switch box of this control device 40 'is provided with a reference setting volume for setting the inclination angle of the working machine, various changeover switches, and a manual switch for directly switching the electromagnetic valve. , Large / medium / small changeover switch for setting the size of the aircraft (large, medium, small), link connection hole selection switch in the link device 3 (the vertical movement scale varies depending on the connection hole),
It includes a parallel / horizontal changeover switch, an automatic / manual changeover switch, etc. for selecting whether the work implement is parallel to the tractor or whether the work implement is maintained horizontally independently.

Next, in the case of the capacitance type tilt sensor, the internal liquid undulates due to vibration, and an error occurs in the output. This state is shown in FIG. This figure shows the output of the tilt sensor when traveling with a 90 mm-high table placed, and overshoot S and undershoot S'occur. These overshoot S and undershoot S '
The generation / convergence state of is determined by the viscosity of the liquid (silicon oil), the shape and size of the container (the space filled with the liquid), and the like. Therefore, if the moving average of the output of the tilt sensor within the predetermined time (t) is taken, the influence of undulation can be eliminated. FIG. 9B shows this state. The output for t seconds is subdivided and taken out, and the average is taken by the microcomputer to obtain the true output of the tilt sensor. The time t is preferably short for a large tractor and long for a small tractor, and usually t = 80 to 150 msec. Then, this time t may be divided into, for example, 32 equal parts, and an average of 32 times may be taken in t seconds.

As described above, if the control is performed while taking the moving average of the detection output from the tilt sensor, the error due to the vibration of the tractor or the like can be reduced.

(Effects of the Invention) As described above, the tilt control device for a working machine according to the present invention is a lateral tilt sensor of a capacitance type installed in front and back, and eliminates the influence of the tilt in the front-rear direction while eliminating the influence of the tilt in the front-rear direction. The inclination is detected, and the hydraulic device is differentially operated based on the detection result to control the inclination of the working machine in the lateral direction. Therefore, it is possible to effectively prevent the occurrence of an error due to the backward inclination of the machine body, It became possible to perform highly accurate tilt control.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention, FIGS. 2 and 3 are front sectional views and side sectional views of a tilt sensor, and FIG.
(a), (b) are explanatory views of the capacitor, (a) is a front view,
(b) is a side view, Fig. 4 (c) is a bridge circuit diagram of the tilt sensor, and Fig. 5 is a graph showing the influence of tilt in the front-rear direction.
FIG. 6 is a side view showing an example in which an inclination sensor is attached to the tractor side, FIG. 7 is a block diagram of a control device, FIG. 8 is a block diagram showing a different embodiment, and FIGS. 9 (a) and 9 (b) are It is a graph showing the influence of vibration. 1 ... tractor, 2 ... work machine, 3 ... link device, 12
...... Lift rod, 13 ...... Lift arm, 15 …… hydraulic cylinder, 20 …… Tilt sensor, 23,24,25 …… Electrode plate, 27
……silicon oil.

Claims (1)

[Claims] 1. A work machine is connected to a lift arm of a tractor via a link or a connecting arm, and a hydraulic cylinder is provided between the lift arm and the link or the connecting arm to detect a lateral tilt. In a tilt control device for a working machine, which hydraulically controls a lateral tilt of a working machine based on a detection result of a tilt sensor, the tilt sensor serves as a tilt sensor for holding a liquid between electrode plates and flowing the liquid during tilting. The capacitance-type sensor that electrically detects the change in the capacitance in the lateral direction caused by the sensor is installed side by side, and the effect of the tilt in the front-back direction is eliminated by combining the two. A characteristic tilt control device for working machines.