JPH03255284A - Electrical drive type actuator protective device - Google Patents

Abstract

PURPOSE:To supply power current to only the selected solenoid for avoiding components from damaging by switching a relay to supply/stop power current to an actuator by switching operation after a lapse of a specified time after the moment of the switching. CONSTITUTION:A relay 38 is provided to freely changed-over supplying and stopping power current by the switching operation of a switch 26 is provided. In addition, a timing control means B is provided to switch the output from a controller 25 to a supplying/stopping state after a lapse of a specified time after the moment of switching of the relay 38 to the state of power supply/ stopping. The relay 38 is turned on after a lapse of the specified time. In addition, a high level signal is output to an AND circuit 37 after the lapse of the second set time. Therefore, even if a transistor Tr1 and Tr2 are erroneously turned on, drive current is prevented from continuously flowing, which avoid circuit components from damaging.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a protection device for an electrically driven actuator, such as an electromagnetic hydraulic control valve, which is installed on, for example, an agricultural tractor.

[Conventional technology]

As a driving structure for the above-mentioned actuator, there is conventionally a structure that was previously filed by the present applicant (Japanese Patent Application No. 1-183914).

In other words, drive current is supplied directly to the actuator from the power supply device via the power transistor.

Further, the electric circuit portion was installed in a control box located near the operator's hand, and the actuator was installed at a location away from the control box near the hydraulic piping.

[Problem to be solved by the invention]

With the above conventional structure, no problems occur during normal operation, but for example, the wiring from the control box to the actuator may be coated due to vibration of the aircraft, contact with the outside, or aging. If the short circuit occurs, an overcurrent will flow through the power transistor, causing a short circuit between the power transistor and the aircraft.
The wiring within this power transistor may melt and remain in an on state. In such a case, problems arise, such as the electromagnetic solenoid operating regardless of the presence or absence of a control signal from the control device.

The present invention prevents malfunction of the actuator while preventing the harmful effects associated with opening and closing of the actuator's large current circuit even if there is a continuity failure in the final drive unit due to a short-circuit failure or the like as described above, and prevents the malfunction of the actuator. The purpose is to prevent damage.

[Means to solve the problem]

A characteristic configuration of the present invention includes a control device that switches and controls a drive circuit that supplies a drive current to an electrically driven actuator between a driving state and a non-driving state by switching an operator-operated switch; a circuit opening/closing means that can freely switch between a state of supplying power current to the actuator and a state of stopping the supply according to a switching operation of the operation switch; and a current supply state of the circuit opening/closing means according to the operation of the operation switch. The output from the control device is switched to a driving state after a predetermined period of time has elapsed from the time when the control device was switched to the non-driving state, and the circuit opening/closing means is set to a current supply stop state after a predetermined time has elapsed from the time when the control device was switched to the non-driving state. There is a point where a switching timing control device is provided.

[For production]

When the operation switch for changing the drive state of the actuator is set to the OFF state, the circuit opening/closing means stops supplying power supply current to the actuator, so the final output stage of the drive circuit may fail due to a short-circuit failure of the connecting wiring to the actuator, etc. Even if this happens, no current will be supplied to the actuator and no malfunction will occur. Further, even in normal operation, since the drive circuit is in a non-driving state when the operation switch is turned off, the final output stage is in an off state, no power supply current is required, and there is no problem in operation.

Moreover, as a result of switching between the circuit opening/closing means and the control device using a single operation switch, there is a difference in the timing of the operation of the two due to a signal delay in the circuit, for example, when the control device is in the driving state. When the circuit opening/closing means is activated,
Since the circuit is opened and closed while a large current is being supplied to the actuator, problems such as damage due to arcing at the switching contacts occur, but by the above-mentioned timing control means, when the circuit opening and closing means is activated, the control device Since the current supply is stopped, the above-mentioned adverse effects do not occur.

〔Effect of the invention〕

Therefore, according to the present invention, by making effective use of the operation switch necessary for actuator switching control and making reasonable improvements, it is possible to prevent malfunction and prevent damage to circuit components due to overcurrent. Now I can do it.

Furthermore, even if a contact switching type structure with high reliability of opening/closing operation is used as the circuit opening/closing means, it is now possible to construct the circuit with high durability without generating arcs.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 5 shows a machine body travel transmission system for switching forward and backward movement of an agricultural tractor.

The running latch (to which the power from the engine (1) is transmitted)
2) and an external clutch (3) are provided, and the power from the running latch (2) is transmitted to the cylindrical input shaft (4) for the running system, and the power from the external clutch (3) is transmitted to the running system. is the input shaft (4) for driving the external power shaft (5).
) is transmitted to the transmission shaft (6) fitted inside.

As shown in the figure, a clutch case (8) is externally fitted and fixed to the input shaft (4) via a key (7), and
The output gear (9) is fitted externally in an idling state, and the input shaft (4)
) An input gear (11) is externally fitted and fixed to a cylindrical intermediate shaft (10) disposed coaxially with the input gear (11).

Moreover, an idle gear (12) and two gears (13), (14) are located between the output gear (9) and the input gear (11).
A reverse gear transmission system consisting of
) and the input shaft (4).
) and a second hydraulic clutch (CL2) that directly transmits the power from the input gear (11) to the input gear (11).
15)..., (16)... and a hydraulic piston (17).

(18), each hydraulic clutch (CL
2), (CL, ) can both be set to a transmission state by supplying pressure oil.

Incidentally, the power from the intermediate shaft (10) is transmitted to the transmission (19).
), a transmission system is formed in such a way that the power is transmitted to the wheels (20) via.

In this transmission system for traveling, the first and second hydraulic clutches (CL2), (CL,) are operated in such a way that shocks are not generated as much as possible during gear shifting due to the operation of the first and second hydraulic clutches (CL2), (CL,). A system is provided to control the pressure of hydraulic oil.

In other words, as shown in Fig. 4, the oil passages (23) and (24) that send pressure oil from the hydraulic pump (21) to the first and second hydraulic clutches (CL2) and (CL), respectively, have electromagnetic proportional A control device is equipped with pressure reducing valves (V1) and (V2), and these two electromagnetic proportional pressure reducing valves (Vl) and (V2) (an example of an actuator) are equipped with a microprocessor (not shown). (25), and the control device (25) is equipped with a forward/reverse setting changeover switch (25).
6) and a control system is formed such that signals from a sensor (S) that detects the acceleration of the running system from the rotation of the front wheels (20) are input, and this control device (25) is connected to each of the electromagnetic proportional pressure reducing valves (Vl). ), (V2) hydraulic clutches (CL
2) The clutch pressure increase characteristic with respect to (CLI) is controlled to be gradual, and automatic pressure increase control is executed in order to reduce the shock when the clutch is engaged.

FIG. 1 shows a control circuit diagram.

Based on the switching operation of the changeover switch (26), the control device (25) selects one of the electromagnetic proportional pressure reducing valves (Vl).

The electromagnetic solenoids (27) and (28) in (2) are driven with a pulse current so that they have a preset boost characteristic.

At this time, the control range of the drive current is set in advance.

A current detection resistor (29) is connected to the lower drive current side of each electromagnetic solenoid (27) and (28).
A smoothing circuit (30) smoothes the voltage across this detection resistor (29).
The average value of the drive current is smoothed through the A/D converter (
31) is digitized and fed back to the control device (25), and the drive current is controlled so as to always maintain the drive current at an appropriate value.

The electric circuit part is located in a control box (32) located near the operator's hand, and is connected to an electromagnetic solenoid (2).
7) and (28) are provided at locations separated from the control box (32).

Drive circuit (3) of each electromagnetic solenoid (27), (28)
3).

(33) has a power transistor (Tr+
) is provided, and this power transistor (Tr 1) is controlled to be turned on or off based on a signal from the control device (25) as described above.

On the collector side of the power transistor (Tr+),
A detection transistor (Tr2) is connected as a short circuit detection means, and this transistor (Tr2) maintains an off state during normal operation, and an electromagnetic solenoid (27),
(28) If a short-circuit failure occurs in the transistor (
Tr2) is turned on to detect a short circuit.

Further, a switching protection circuit (as a means for switching the drive state) for forcibly switching the signal from the control device (25) to a non-operating state in accordance with the detection operation of the detection transistor (Tr2) and maintaining that state is provided. 35). Specifically, as the transistor (Tr2) turns on, the input transistor (Tra) turns on, a low level is input to the latch circuit (36), and the output is switched from a high level signal to a low level signal. Change. Accordingly, the AND circuit (37) outputs a low level signal, the power transistor (Tr+) is turned off, and the current supply to the electromagnetic solenoids (27) and (28) is stopped.

The vehicle parking brake (SW) is also provided with a detection switch (SW) that detects whether or not the vehicle parking brake (not shown) is operated. ) is provided with drive restraining means (A) that restrains the drive from being performed as described above when the drive is operated from the neutral position to any one of the positions. In other words, a signal from the detection switch (SW) and a signal from the changeover switch (26) are given to the control device (25), and when both are in the on state, the electromagnetic solenoid (2
7) and (28) are maintained at a low level. Further, in the drive check state, a buzzer (Bz) is configured to generate a warning sound.

A relay (as a circuit opening/closing means) that can freely switch between supplying power current to the electromagnetic solenoids (27) and (28) and stopping the supply according to the switching operation of the changeover switch (26). 38).

(38) is provided. Further, after a predetermined period of time has elapsed from the time when the relays (38), (38) are switched to the power supply state due to the operation of the changeover switch (26), the control device (
After a predetermined period of time has elapsed since the output from the control device (25) is switched to the drive state and the output from the control device (25) is switched to the non-drive state, the relay (38), (
38) is provided with a timing control device (B) for switching the current supply to the stop state.

This timing control device (B) is provided as a control program in the control device (25), and FIG. 3 shows a timing chart and FIG. 2 shows a control flowchart. That is, in step Sl, the changeover switch (26)
When the above operation is performed, it is determined in step S2 whether the switch changeover is a changeover operation from an off state to an on state, and if the result is negative, the process proceeds to step S3, and it is determined that the switch changeover is a changeover operation from an off state to an on state. It is determined whether If the result in step S2 is affirmative, it is determined in step S5 whether or not the measured time has elapsed by a first set time (tl), and if it has elapsed, the relay (38) is turned on in step S6.

Furthermore, time measurement is performed in step S7, and a second time measurement is performed in step S8.
When it is determined that the set time (t2) has elapsed, a high level signal is output to the AND circuit (37) in step S9.

Further, when the result is affirmative in step S3, time measurement is performed (step 5IO), and when it is determined that the third set time (t3) has elapsed (step 5l1), a low level is input to the AND circuit (37). Step 51 to output the signal
2), the clock is further measured (step 513), and when the fourth set time (t,) has elapsed (step 514), the relay (38
) is turned off (step 515).

With this configuration, the electromagnetic solenoids (27), (2
8), the drive current will not continue to flow even in the event of an on-failure of the power transistors (Tr+) and (Tr+), which will prevent inconveniences such as unexpected aircraft runaway. This does not occur, and there is little risk of damage to circuit components.

Moreover, when the relays (3B) and (38) are activated, the power transistors (Tr+) and (Tr+) are always in the off state, so the relays (38) and (38) cannot be opened or closed when a large current is flowing. This means that there is no wear on the contacts.

It should be noted that the first set time (t, ) and the third set time (t3) are
) may consider only mechanical time delays caused by hardware.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of drawings]

The drawings show an embodiment of the protection device for an electrically driven actuator according to the present invention, in which Fig. 1 is a control circuit diagram, Fig. 2 is a control flowchart, Fig. 3 is a control timing chart, and Fig. 4 is a hydraulic control system diagram. , FIG. 5 is a sectional view of the hydraulic clutch. (25)...Control device, (26)...
Operation switch, (38)...Circuit opening/closing means, (
B)... Timing control device, (V1), (V
2) Actuator.

Claims (1)

[Claims] A control device that switches and controls a drive circuit (33) that supplies drive current to the electrically driven actuators (V_1) and (V_2) between a drive state and a non-drive state by switching a human operation switch (26). (25), circuit opening/closing means capable of switching freely between a state of supplying power current to the actuators (V_1) and (V_2) and a state of stopping the supply according to the switching operation of the operation switch (26). (38), and the operation switch (
After a predetermined period of time has elapsed since the switching of the circuit opening/closing means (38) to the current supply state due to the operation of step 26), the output from the control device (25) is switched to the drive state, and the control device (25) is switched to the drive state. A protection device for an electrically driven actuator, comprising a timing control device (B) that switches the circuit opening/closing means (38) to a current supply stop state after a predetermined period of time has elapsed from the time of switching to a non-driving state.