JPH0242881Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a hydraulic power unit mounted on a vehicle, etc., and more particularly to a hydraulic power unit that ensures the hydraulic pressure in a hydraulic circuit at a predetermined pressure when a pressure switch that sets the hydraulic pressure in the hydraulic circuit is abnormal. .

The hydraulic pressure generating device mounted on a vehicle and driving various actuators such as a hydraulic cylinder for clutch switching includes a motor, a hydraulic pump driven by the motor to supply pressure oil to a hydraulic circuit, and a hydraulic pump that supplies pressure oil discharged from the hydraulic pump. It consists of an accumulator that temporarily accumulates pressure, a pressure switch that detects the oil pressure in the hydraulic circuit and controls the motor to drive (on) and stop (off) to set the oil pressure to a predetermined pressure. A predetermined pressure oil is supplied to normally operate the actuator.

However, if the pressure switch in the hydraulic power unit malfunctions and malfunctions, it becomes impossible to control the motor, and there is a risk that the motor may not start or may continue to rotate and burn out. In either case, the hydraulic pump ceases to be driven, and the hydraulic power unit immediately loses its function and ceases to generate pressure oil. As a result, actuators such as the clutch switching cylinder become inoperative, causing problems such as the vehicle becoming unable to be driven.

The present invention was developed in view of the above points, and the purpose of this invention is to ensure that the hydraulic pressure in the hydraulic circuit is at a predetermined pressure when the first pressure switch that sets the hydraulic pressure in the hydraulic circuit is abnormal. In order to do this, the present invention includes a motor, a hydraulic pump driven by the motor and supplying pressure oil to a hydraulic circuit,
a first pressure switch that opens when the hydraulic pressure in the hydraulic circuit reaches a first set pressure and closes when the hydraulic pressure reaches a second set pressure lower than the first set pressure; and a drive for the motor. A hydraulic power unit comprising a switching circuit connected to a circuit and driven by the first pressure switch to open and close the drive circuit,
A second pressure that opens when the hydraulic pressure reaches a third set pressure that is lower than the first set pressure and closes when the hydraulic pressure reaches a fourth set pressure that is lower than the third set pressure. a switch, and a switching means for switching a switch that drives the switching circuit from the first pressure switch to the second pressure switch when the first pressure switch is continuously closed for a predetermined time or more. It was designed to be provided.

According to the hydraulic power unit of the present invention, if the closed state of the first pressure switch does not continue for a predetermined period of time or more, the drive of the motor is controlled according to the opening and closing of the first pressure switch. When the closed state of the pressure switch continues for a predetermined time or more, the switch that drives the switching circuit is switched from the first pressure switch to the second pressure switch, and the motor is driven in accordance with the opening and closing of the second pressure switch. controlled. Therefore, even in the event of an abnormality such as a short circuit in the first pressure switch, the second pressure switch maintains the oil pressure in the hydraulic circuit between the third and fourth set oil pressures.

An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows the circuit configuration of a hydraulic power unit to which the present invention is applied, in which a drive shaft 1a of a hydraulic pump 1 is connected to a drive shaft 3a of a motor 3 via a coupler 2, a suction port is connected to a tank 4, and a discharge port is connected to a tank 4. is connected via an oil passage 5 to an accumulator 6 and an actuator, such as a clutch switching cylinder 7 of a vehicle (not shown), and a relief valve 8 is connected between the oil passage 5 and the tank 4. Two pressure switches 10 and 11 are connected in parallel to the oil passage 5 via an oil passage 9. The pressure switch 10 is opened when the oil pressure P in the oil passage 5 reaches a first set pressure P ₁ (upper limit value), and a second set pressure P ₂ (<P _{1 ) lower} than the first set pressure P 1 is opened. ) (lower limit), it is closed. Further, the pressure switch 11 is, for example, a pressure switch for alarm, and is opened when a third set pressure P ₃ (<P _{1 )} (upper limit) lower than the first set pressure P 1 is reached; Fourth set pressure lower than set pressure P ₃
When P ₄ (<P ₃ ) (lower limit value) is reached, it is closed and the alarm lamp 21 is turned on.

The positive terminal of the battery 12 is the main switch 13
The negative terminal is connected to the wire 20 at the contact 13a of the
The line 20 is grounded. Main switch 13
The contact 13b of the relay circuit 14 is connected to the contact 14a of the relay circuit 14, one terminal of the coil 14c, and the contact 15a of the alarm switch 15.
4b is connected to one terminal of the motor 3, the other terminal of which is connected to the wire 20, and the coil 1
The other terminal of 4c is connected to the contact 19a of the relay 19 of the timer relay 17, and the alarm switch 15
The contact 15b is connected to the line 20 via the alarm lamp 16. Alarm switch 15 and relay 19
The movable contacts of the alarm switch 15 are opened when the relay 19 is switched to the contact 19b, and closed when the relay 19 is switched to the contact 19c.

Input terminal 1 of timer 18 of relay with timer 17
8a is the contact 13b of the main switch 13, and the connection terminal (ground terminal) 18b is the contact 1 of the pressure switch.
0a and one end of a diode 22, and the other end of the diode 22 is connected to a contact 19c of the relay 19. A connection terminal 18c of the timer 18 is connected to one end of a coil 19d of a relay circuit 19, and the other end of the coil 19d is connected to a line 20. Contact 19c of relay 19 is pressure switch 1
The pressure switch 11 is connected to the contact 11a of the pressure switch 11.
The contact 11b is connected to the line 20 via the alarm lamp 21.

The timer 18 is constructed as shown in FIG. 2, for example, and the emitter of the transistor Tr ₁ is connected to the line 23.
is connected to _the connection terminal _18a through
The line 24 is connected to the connection terminal 18b, and the collector is connected to the base of the transistor Tr ₂ via the resistor R ₂ . A series circuit of a resistor R ₄ and a resistor R ₅ is connected between the lines 23 and 24, and the connection point a between these resistors R ₄ and R ₅ is connected to the operational amplifier 2.
It is connected to the inverting input terminal of 5.

Furthermore, a series circuit of a resistor R ₆ , a diode D ₁ and a capacitor C ₂ is connected between the lines 23 and 24, and the cathode of the diode D ₁ and the capacitor C ₂
The connection point b is connected to the cathode of the diode D ₂ , and the anode of the diode D ₂ is connected to the non-inverting input terminal of the operational amplifier 25 . The collector of transistor Tr ₂ is connected to connection point b, and the emitter to line 24. The non-inverting input terminal of the operational amplifier 25 is connected to the line 24 via a resistor _R7 ;
The output terminal is connected to the connection terminal 18c and also to the non-inverting input terminal via a resistor _R8 .
The timer time of the timer 18 is set to an appropriate time depending on the time constant of the charging circuit formed by the resistor _R6 and the capacitor _C2 , and in this embodiment, it is approximately 1/3 of the rated time of the motor 3. It is set to approximately twice the maximum normal usage time.

The operation will be explained below.

First, in the initial state where the oil pressure in the hydraulic circuit is 0, both pressure switches 10 and 11 are closed, and the contacts 14a and 14 of the relay 14 in the motor drive circuit are closed.
14b is opened, and the relay 19 of the timer relay 17 is switched to contact 19b. When the main switch 13 is closed, the coil 14 of the relay 14
c is energized, contacts 14a and 14b are connected, motor 3 is started, and hydraulic pump 1 is driven. Accompanying this, the hydraulic pressure P of the hydraulic circuit increases, is accumulated in the accumulator 6, and is supplied to the cylinder 7 (not shown).

When the oil pressure P reaches the set pressure _P3 , the pressure switch 11 is first opened, and when the oil pressure P further increases and reaches the set pressure _P1 (the upper limit of the pressure switch 10), the pressure switch 10 is opened. When the pressure switch 10 is opened, the relay coil 14c of the relay 14 is deenergized, contacts 14a and 14b are opened, the motor 3 is stopped, and the hydraulic pump 1 is accordingly stopped. From the state where this oil pressure P is 0, the set pressure
The time it takes to reach P ₁ is about several seconds. When the cylinder 7 is driven and the oil pressure P decreases and reaches the set pressure P ₂ (lower limit value of the pressure switch 10), the pressure switch 1 is activated.
0 is closed, the coil 14c of the relay 14 is energized again, and the motor 3 is started to drive the hydraulic pump 1. Accompanying this, the oil pressure P increases. When the set pressure _P1 is reached, the pressure switch 10 is opened.
In this way, the oil pressure P is maintained within the range of the set pressures _P1 and _P2 .

On the other hand, when the main switch 13 is closed, the second
The reference voltage Vr at the connection point a of the timer 18 of the timer-equipped relay 17 shown in the figure is input to the inverting input terminal of the operational amplifier 25, and the transistor Tr ₁ becomes conductive, and accordingly the transistor Tr ₂ becomes conductive.
Transistor Tr ₁ conducts for a short time until capacitor C ₁ is charged, and conduction of transistor Tr ₂ causes capacitor C ₂ to discharge. That is, the timer 18 is reset. When the capacitor C ₁ is charged and the transistor Tr ₂ becomes non-conductive, charging of the capacitor C ₂ starts, and the terminal voltage Vc of the capacitor C ₂ increases accordingly.

If the oil pressure P reaches the set pressure P ₁ before the terminal voltage Vc of the capacitor C ₂ reaches the reference voltage Vr, the pressure switch 10 is opened, and as a result the capacitor
C ₂ charging is stopped. Therefore, no signal is output from the output terminal 18c of the timer 18, and the relay 19 remains switched to the contact 19b. The hydraulic pressure P of the hydraulic circuit is controlled within the range of the set pressures _P1 and _P2 by opening and closing the pressure switch 10.

Now, assume that the pressure switch 10 is caused by some reason, for example, the contacts 10a and 10b are seized and do not open even when the set pressure _P1 is reached. The motor 3 continues to rotate while the pressure switch 10 is closed. The timer 18 starts operating when the pressure switch 10 is closed, and the terminal voltage Vc of the capacitor _C2 increases.
When this voltage Vc exceeds the reference voltage Vr, the output voltage of the output terminal 18c becomes Vo, and the relay 1
The coil 19d of No. 9 is energized. When the coil 19d is energized, the relay 19 switches from the contact 19b to the contact 19.
It is switched to c. As a result, the coil 14c of the relay 14 is connected to the contact 11a of the pressure switch 11 via the contact 19c of the relay 19.

At the same time, the alarm switch 15 is closed and the alarm lamp 16 is turned on. The lighting of this warning lamp 16 notifies the driver of an abnormality in the hydraulic circuit. When the relay 19 is switched to the contact 19c, even if the output voltage Vo of the timer 18 becomes 0, it is no longer switched to the contact 19b, but remains switched to the contact 19c. As a result, pressure switch 10 and timer relay 17 are disconnected from the motor drive circuit, and alarm lamp 16 continues to be lit.

On the other hand, the pressure switch 11 is open when the set pressure P ₁ is reached, and therefore the coil 1 of the relay 14
4c is deenergized, contacts 14a and 14b are opened, the motor drive circuit is opened, and the motor 3 is stopped. When the oil pressure P in the hydraulic circuit decreases and reaches the set pressure P ₄ (the lower limit value of the pressure switch 11), the pressure switch 11 is closed, the coil 14c of the relay 14 is energized, and the contacts 14a and 14b are closed. The motor 3 starts and drives the hydraulic pump 1. This causes the oil pressure P to rise. And this oil pressure P is the set pressure
When P ₃ (the upper limit of the pressure switch 11) is reached, the pressure switch 11 is opened, the coil 14c of the relay 14 is deenergized, the motor 3 is stopped, and the hydraulic pump 1 is stopped. Hydraulic pressure P decreases and sets pressure again
When P ₄ is reached, the pressure switch 11 is closed and the motor 3 is started. In this way, the oil pressure P of the hydraulic circuit is maintained within the range between the upper limit value P ₃ and the lower limit value P ₄ of the pressure switch 11. This makes it possible to ensure that the hydraulic pressure in the hydraulic circuit is at least sufficient to drive the cylinder 7.

As explained above, according to the present invention, there is provided a motor, a hydraulic pump driven by the motor and supplying pressure oil to a hydraulic circuit, and a first hydraulic pressure in the hydraulic circuit.
A hydraulic power unit comprising: a first pressure switch that operates when a set pressure is reached; and a switching circuit connected to a drive circuit of the motor and driven by the first pressure switch to open and close the drive circuit , a second pressure switch that operates when the oil pressure reaches a third set pressure lower than the first set pressure; and a second pressure switch that starts operating at the same time as the first pressure switch is closed, and that operates for a predetermined period of time. After the lapse of time, the first
switching means for switching the switching circuit from the first pressure switch to the second pressure switch when the pressure switch is closed, thereby preventing the first pressure switch from malfunctioning. Even in such a case, the motor is not driven for longer than the predetermined time, thereby preventing burnout of the motor. Furthermore, it becomes possible to ensure the hydraulic pressure of the hydraulic power unit at the third set pressure,
It is possible to ensure the operation of the actuator driven by the hydraulic power unit, and it is possible to prevent a vehicle etc. from becoming inoperable.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a hydraulic power unit to which the present invention is applied, and FIG. 2 is a detailed circuit diagram showing an embodiment of the timer circuit of the timer-equipped relay shown in FIG. 1... Hydraulic pump, 3... Motor, 6... Accumulator, 7... Cylinder, 10, 11... Pressure switch, 13... Main switch, 14... Relay, 15... Alarm switch, 16, 21... Warning lamp, 17...Relay with timer, 18...Timer, 19...Relay.

Claims (1)

[Claims for Utility Model Registration] 1. A motor, a hydraulic pump driven by the motor and supplying pressure oil to a hydraulic circuit, which opens when the hydraulic pressure in the hydraulic circuit reaches a first set pressure,
a first pressure switch that closes when a second set pressure lower than the first set pressure is reached; and a first pressure switch that is connected to a drive circuit of the motor and driven by the first pressure switch to open and close the drive circuit. a switching circuit that opens when the hydraulic pressure reaches a third set pressure lower than the first set pressure, and a fourth set pressure lower than the third set pressure; a second pressure switch that closes when the pressure reaches A hydraulic power unit comprising switching means for switching to the second pressure switch. 2. Utility model registration claim 1, characterized in that the switching means is a timer-equipped relay consisting of a timer that outputs a signal after a predetermined timer period has elapsed, and a relay that is driven by the signal.
Hydraulic power unit as described in section.