JPH0665245B2 - Lift control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is configured such that a lift arm for raising and lowering a ground working device provided on a vehicle body is configured to be moved up and down by an operation of an actuator, and an engine provided on the vehicle body is started. Based on the signal from the lift arm sensor that sometimes detects the amount of lift of the lift arm and the signal from the operation tool sensor that detects the setting position of the operation tool for controlling the lift arm, the relative movement of the operation tool with respect to the lift arm. The present invention relates to a lift control device configured to perform lift control according to an operating tool only after a time point when the physical relationship is set to be substantially the same or high.

[Conventional technology]

The lifting control device having the above-mentioned configuration is a safety mechanism provided in an agricultural tractor or the like, and its operation is performed by a relative positional relationship between the lift arm and the operating tool at the time of starting the engine provided in the vehicle body. If the values do not match, it is determined that the operating tool is being operated while the engine is stopped, and the operation of the lift arm is restrained (not described in the reference).

[Problems to be solved by the invention]

Here, considering the operation of the lift arm, since the level of the lift arm is determined in correspondence with the set position of the operating tool, the operating tool is set to the operation end position on the higher level side, so that the highest level is obtained. Will be set. However, for example, in a structure in which the lift arm is moved up and down by a hydraulic cylinder and the relief valve operates when the operation tool is set to the operation end position, the lift arm upper limit position is not constant due to the magnitude of the load on the engine. Sometimes.

In other words, the lift control range of the lift arm by the actuator that drives the lift arm up and down is generally set to be somewhat narrower than the limit of the mechanical operation range of the actuator. The lift arm may exceed the upper limit of the lifting control range and reach a mechanical operation limit due to the light weight of the work device and the magnitude of its operating speed.

In this way, when the engine is stopped with the lift arm exceeding the upper limit of the lifting control range, the above-mentioned restraint due to the relative positional relationship between the lift arm and the operating tool does not work, and Even if the operation tool is artificially set to the operation end position on the high level side, the relative positional relationship between the lift arm and the operation tool does not match, so the restraint state may not be released, and there is room for improvement.

An object of the present invention is to construct a lifting control device that does not restrain the lifting control as easily as possible by rational modification unless the relative positional relationship between the lift arm and the operating tool is largely different. .

[Means for solving problems]

A feature of the present invention is that a lift arm for raising and lowering a ground work device provided in a vehicle body is configured to be moved up and down by an operation of an actuator, and a lift arm that detects the amount of elevation of the lift arm when the engine provided in the vehicle body is started. Based on the signal from the sensor and the signal from the operating tool sensor that detects the set position of the operating tool for controlling the lift arm, the relative positional relationship of the operating tool with respect to the lift arm is set substantially equal to or higher. In a lifting control device configured to perform lifting control according to an operation tool only after a point of time, a signal of a lift arm sensor is corrected by a predetermined amount to a lower side of a lift arm at the time of starting the engine, or an operator. Correct the sensor signal by a certain amount to the raising operation side of the operation tool, or lift arm sensor signal and operation tool sensor signal There both in that provided a signal changing means for a predetermined amount corrected in the direction in which the difference between each other is reduced,
The action and effect are as follows.

[Work]

a.When the engine is started, the lifting control according to the operation tool is performed only after the relative position of the operation tool with respect to the lift arm is set to be substantially the same or high, and otherwise the lifting control device is operated. Since it will be in a restraining state,
The rapid lowering of the lift arm based on the relative displacement between the lift arm position and the operation tool position can be restrained.

b. The release of the restraint state can be released by manually operating the operation tool so as to match the lift arm position. At this time, the upper limit stop position of the lift arm is, for example, as shown in FIG. Even if the lift arm is at a position level (L1) higher than the upper limit level (L0) of the normal control operating range set by the operation tool (5), such as after being lifted up with a small load on the engine, The restraint state of the lifting control is surely released by the action of the signal changing means for correcting the signal of the lift arm sensor or the signal of the operation tool sensor by a predetermined amount in the direction of reducing the positional deviation between the lift arm and the operation tool. .

c. When the relative positional relationship between the lift arm and the operation tool is largely deviated from the correction amount by the signal changing means even when the correction is performed by the action of the signal changing means at the time of starting the engine. The above-mentioned restraint state of the elevation control is maintained. Further, such signal correction control is performed only when the engine is started, and thereafter, normal lifting control based on the operation of the operation tool is performed.

〔The invention's effect〕

Therefore, while it is possible to restrain the lifting operation accompanied by the rapid lowering of the ground work device at the time of starting the engine, the stop position of the lift arm that is driven up and down by the actuator sets the upper limit of the lifting control by the operation tool. Even when it is displaced to a position beyond the limit, it is possible to provide a lifting control device that can reliably release the lifting control restraint state when the engine is started.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 3, a lift arm (3) swingably moves up and down by the operation of a hydraulic cylinder (2) as an example of an actuator at the rear of a vehicle body (1) equipped with an engine (not shown).
And a lever-type operation tool (5) for moving the lift arm (3) up and down on the right side of the driver's seat (4) provided on the vehicle body (1), and on the upper surface of the rear folder (6). A control box (7) for controlling the operation of the lift arm (3) is provided to constitute an agricultural tractor.

As shown in the figure, a rotary ground working device (9) is connected to the rear end of the vehicle body (1) via a three-point link mechanism (8) which is operated to move up and down by the lift arm (3). The lift arm (3) is provided with a lift arm sensor (10) for detecting the level of the ground working device (9) with respect to the vehicle body from the swing angle thereof, and the ground working device (9) has the ground working device. The device (9) is provided with a cover sensor (11) for detecting the working depth of the ground working device (9) from the swing angle of the rear cover (9a), and the operation tool (5) is provided with the operation amount. An operation tool sensor (12) for detecting is provided.

As shown in FIG. 1, the control box (7) is internally provided with a lift control device (C) including a microprocessor (not shown).
Is a position control means (D) for arbitrarily setting the swing angle of the lift arm (3) by operating the operation tool (5),
A cover sensor (11) for maintaining the level of the ground working device (9) at the working depth given by the working depth setting device (14) operated by the dial (13) provided in the control box (7).
An automatic working depth control means (E) which operates by a feedback signal from the drive circuit, a drive circuit (F) which drives an electromagnetic valve (15) for the hydraulic cylinder (2), and a drive circuit (F) which satisfies a specific condition. ) Of the restraining means (G) and the signal changing means (H) for changing the signal value from the lift arm sensor (3), and these four means (D), (E), (G) ) And (H) are each composed of a program set in a microprocessor.

Further, in the lifting control device (C), control is started only when the relative positional relationship of the operating tool (5) to the lift arm (3) is at the lower side at the time of starting the engine. The program is set.

That is, as shown in FIG. 1 and FIG. 2, the vehicle body (1) is provided with a sensor (16) for detecting that an engine starting operation has been performed, and this sensor (16) allows the engine starting operation to be performed. When is detected, initialization is performed (# 1 step), and then signals from the lift arm sensor (10) and the operation tool sensor (12) are input (# 2 step).

Next, a predetermined value is added to the signal value of the operation tool sensor (12) (# 8 step), and this added signal value is compared with the lift arm sensor signal (# 4 step) to determine that the added signal value is If it is smaller, it is in a restraining state in which the control of # 2 step to # 4 step is repeated. That is, the lift arm signal and the operation tool sensor signal are read again, a predetermined value is added to the read operation tool sensor signal, the addition signal value is obtained again, and this is compared with the lift arm sensor signal. The restraint state is revealed by maintaining the state in which the actual lifting control is not performed.

At this time, even if the signal of the lift arm sensor (10) is larger than the signal of the operation tool sensor (12), if the difference is smaller than or equal to the predetermined value, the added signal value is the lift arm sensor. Since it is greater than or equal to the signal, the check state is not established, and step # 5 is executed to enter the non-check state.

Next, if the operation tool (5) is in the position control area (P) as shown in FIG. 1, the signal value from the operation tool sensor (12) is input (# 5 step) if it is in the non-checking state. (# 6 step), position control is performed (# 7 step),
If the position (A) is outside the control area (P), the automatic plowing depth control is performed (# 8 step), and this control is continued until it is reset (# 9 step).

In the flow chart, # 3 step is signal changing means (H), # 4 step is check means (G), # 7 step is position control means (D), and # 8 step is automatic tilling depth control means (E). To call.

Further, in the control system, when the lift arm (3) is set to the highest level by position control, the relief valve (18) interposed in the path from the hydraulic pump (7).
The upper limit position is determined by the operation of.

[Another embodiment]

In addition to the above embodiment, the present invention corrects the signal from the lift arm sensor to the descending side, or corrects the signal from the lift arm sensor to the descending side and simultaneously corrects the signal from the operation tool sensor to the ascending side. It may be configured to perform signal processing.

Further, the signal changing means may be implemented by a hard circuit including a logic gate and a comparator.

Reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

The drawings show an embodiment of a lifting control device according to the present invention.
FIG. 3 is a block diagram showing the configuration of the lifting control device, FIG. 2 is a flowchart showing the operation of the lifting control device, and FIG.
The figure is a side view showing the rear part of the tractor. (1) …… Body, (2) …… Actuator, (3)…
… Lift arm, (5) …… Operating tool, (10) …… Lift arm sensor, (12) …… Operating tool sensor, (H) …… Signal changing means,

Claims (1)

[Claims] 1. A lift arm (3) for raising and lowering a ground working device provided on a vehicle body (1) is configured to be moved up and down by an operation of an actuator (2), and an engine provided on the vehicle body (1) is started. Occasionally, a lift arm sensor (1
Signal from (0) and operation tool for lift arm control (5)
Based on the signal from the operating tool sensor (12) that detects the set position of the operating tool (5) for the lift arm (3)
Is a lifting control device configured to perform lifting control according to the operation tool (5) only after the relative positional relationship between the lift arms is set to be substantially equal to or high. The signal of the sensor (10) is corrected to the lower side of the lift arm (3) by a predetermined amount, or the signal of the operation tool sensor (12) is corrected to the upward operation side of the operation tool (5) by a predetermined amount, or the lift is lifted. A lifting control device provided with signal changing means (H) for correcting a predetermined amount of both the signal of the arm sensor (10) and the signal of the operating tool sensor (12) in a direction in which the difference between them is reduced.