JPH0228505B2 - HOIIRUSHIKISAGYOKIKAINIOKERUHIJOYOSUTEARINGUKAIRO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a wheel-type working machine equipped with power steering, such as a rough terrain crane or a wheel loader, in which the power source of the power steering is changed from an engine-driven pump to an electric motor in order to maintain the steering function when the engine stalls. This relates to an emergency steering circuit for switching to a pump.

Conventionally, as shown in FIG. 2, this type of emergency steering circuit connects an electric motor b that drives an emergency steering pump a to a power source via a contact _c1 of an emergency steering relay c. Relay c is connected to a power source via manual switch d, and when the driver turns on manual switch d when the engine stalls, relay c is activated to energize electric motor b, which in turn turns on emergency steering pump a. It is configured to drive.

However, according to this configuration, since the driver operates switch d after actually sensing that the engine has stalled,
It takes a certain amount of time until pump a is activated and the steering function is restored. For this reason, there was a serious defect in that while the vehicle was running, dangerous situations such as obstacles and curves could not be avoided during this steering disabled time.

SUMMARY OF THE INVENTION Therefore, the present invention aims to provide an emergency steering circuit for a wheel-type working machine that can automatically detect engine stalling in advance and operate the emergency steering pump without delay, thereby reliably maintaining the steering function. be.

The present invention is characterized by having a power steering system, and as a power source for the power steering, a main steering pump is used for steady running, which is driven by an engine, and a main steering pump is used when the engine is stalled, which is driven by an electric motor. In a wheel-type working machine, the electric motor is configured to have on-off voltage controlled by an emergency steering relay, and detects the engine rotation speed and detects when the rotation speed is below a predetermined value. an engine speed detecting means that issues an engine stall warning signal when the engine stall warning signal decreases to 1, a first contact that is controlled by an output signal from the detecting means and closes when the engine stall warning signal is input; and a first contact that closes at any other time. an engine stall detection relay having a second contact that closes when the engine stall detection relay is turned on, and a relay that is energized to form a self-holding circuit when a key switch for starting the engine is turned on and a second contact of the engine stall detection relay is closed; an emergency steering circuit for a wheeled working machine, comprising a contact that closes when the relay is activated, and a series circuit of this contact and a first contact of the engine stall detection relay is connected in series with the emergency steering relay; exists in

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

Reference numeral 1 denotes an emergency steering pump, 2 an electric motor for driving the pump 1, and 3 an emergency steering relay, in which a contact 3a of the relay 3 and a series circuit of the electric motor 2 are connected between a power source. The configuration up to this point is the same as the conventional circuit shown in Figure 2, and in this circuit, the emergency steering relay 3 is
The power is turned on and off by the following control circuit.

This control circuit includes, as main components, an engine rotation speed detection means for detecting the engine rotation speed, and an engine stall detection relay (in the figure, a first and a (Only two contacts 4 and 5 are shown)
, key switch 6 for starting the engine, and timer 7
and a timer holding relay 8. Although not shown, the engine rotation speed detection means includes a sensor that outputs the engine rotation speed as a pulse signal;
It consists of a frequency-voltage converter that converts the pulse output of this sensor into voltage, a comparator that compares the output voltage of the converter with a reference voltage, etc. (hereinafter referred to as the engine stall precursor rotation speed), an engine stall warning signal is sent to the engine stall detection relay. This engine stall detection relay closes the first contact 4 when the engine stall warning signal is input.
In other cases, when the engine speed is equal to or higher than the predetermined speed and the engine speed is maintained at a constant speed including idling, the second contact 5 closes. It should be noted that various other means for detecting the engine speed may be selected, such as means that utilize the output voltage of the alternator.

The timer 7 and the timer holding relay 8 are connected in parallel. This parallel circuit includes the second contact 5 of the engine stall detection relay and the contact 9a of the battery relay 9.
It is connected between the power supply via. The battery relay 9 is connected in series to the key switch 6 and inserted between the power supplies, and when the key switch 6 is turned on, a contact 9a of the relay 9 closes. At this time,
If the second contact 5 of the engine stall detection relay is closed, the timer 7 and the timer holding relay 8 are simultaneously energized via the battery relay contact 9a and the engine stall detection relay second contact 5. A normally open contact 8b of the timer holding relay 8 is a normally closed contact 10b of an auxiliary relay 10 provided in an engine stop circuit, which will be described later.
This series circuit is connected in parallel with the second contact 5 of the engine stall detection relay. Therefore, when the timer holding relay 8 is energized and activated as described above, a self-holding circuit of the timer holding relay 8 is formed by the contact 8a of the relay 8 and the auxiliary relay normally closed contact 10b. Therefore, from now on, the timer 7 is kept energized regardless of whether the engine stall detection relay is activated (the second contact 5 is turned off). The timer 7 closes the timer contact 7a after a predetermined period of time has elapsed since the timer 7 was energized as described above. This timer contact 7a is the first contact 4 of the engine stall detection relay.
It is connected in series with a manual selection switch 11 for excluding engine stalling during crane work, and this series circuit is connected between the battery relay contact 9a and the emergency steering relay 3. The activation delay time of the timer 7 is set in consideration of the time required for the engine rotation speed to reach steady rotation (starting completion) after the engine rotation speed exceeds the engine stall precursor rotation speed at the time of engine startup.

12 is a manual engine stop switch, 13
is an engine stop relay connected in series with the switch 12, and the auxiliary relay 10 is connected in parallel with this engine detection relay 13, and when the engine stop switch 12 is turned on, both relays 1
0 and 13 operate simultaneously. A contact 13a of the engine stop relay 13 is connected in series with a solenoid 14 of an electromagnetic opening/closing valve provided in the fuel supply path of the engine, and when the engine stopping relay 13 is activated, the solenoid 14 is energized to open/close the electromagnetic opening/closing valve. By closing the valve, the fuel supply path to the engine is cut off and the engine is stopped. Further, when the normally closed contact 10b of the auxiliary relay 10 is opened due to the operation of the auxiliary relay 10, the power supply to the timer 7 and the timer holding relay 8 is cut off. Reference numeral 15 designates an emergency switch for manually operating the emergency steering relay 3, which drives the emergency steering pump 1 when the main steering pump driven by the engine fails.

Thus, when the engine is stopped, the circuit turns on the key switch 6 from the state shown in the figure to start the engine. At the time of starting the engine, when the engine speed exceeds the engine stall precursor speed, the contact of the engine stall detection relay is switched from the first contact 4 to the second contact 5 based on the detection signal from the engine stall detection means. As a result, the timer 7 and the timer holding relay 8 are simultaneously energized via the battery relay contact 9a and the second contact 5 of the engine stall detection relay, and the normally open contact 8a of the relay 8 and the normally open contact 1 of the double auxiliary relay 10 are energized.
0b forms a self-holding circuit of the timer holding relay 8. Therefore, even if the engine speed decreases thereafter, the timer 7 continues to be energized.
Conversely, even if the engine speed drops to the engine stall precursor speed due to a poor start, the timer contact 7a remains off as long as the timer 7 is within the set time (estimated start time). Since the emergency steering relay 3 is not energized, it is possible to prevent inconveniences such as the electric motor 1 rotating unnecessarily and wasting battery current.

After the set time of the timer 7 has elapsed, the timer contact 7a closes and the emergency steering relay 3 is activated.
In other words, the emergency steering pump 1 is in standby mode. Now, when the engine speed drops to the engine stall precursor speed while driving, the engine stall detection relay is activated by the engine stall warning signal from the engine speed detection means and the contact is switched from the second contact 5 to the first contact 4. Emergency steering relay 3 is energized and activated,
The electric motor 2 is energized via the contact 3a of the relay 3. As a result, emergency steering pump 1
is driven and supplies pressure oil to the power cylinder.

In this way, this circuit constantly monitors the engine speed while driving, and based on this speed,
The emergency steering pump 1 is configured to be driven as soon as possible before the engine actually stalls. Therefore, when using this circuit, there is no blank time until the pump is switched as in the case of the conventional circuit, and the steering function can be reliably maintained without interruption.

Note that when the engine speed, which has once decreased to the engine stall precursor speed, recovers, the first contact 4 of the engine stall detection relay is turned off, so that the electric motor 1 is de-energized and the pump 1 is stopped. Further, in such an automatic control system, when the key switch 6 is turned off, the engine stop switch 12 is turned on and the auxiliary relay 10 is activated, and its normally closed contact 10b is turned on.
When opens, it is released. In addition, in the event of a failure of the main steering pump driven by the engine, the emergency steering pump 1 can be turned on by turning on the emergency switch 15, regardless of the automatic control described above.
is driven. On the other hand, during crane work on a crane vehicle such as a rough terrain crane, the selection switch 11 is switched to the crane operating system, so even if the engine stalls during the crane work, the emergency steering pump 1 is not driven.

By the way, in the above embodiment, the key switch 6 is turned on and the second contact 5 of the engine stall detection relay is turned on.
When closed, both the timer 7 and the timer holding relay 8 are energized simultaneously to form a self-holding circuit,
Although the configuration is such that the timer contact 7a is closed after a certain period of time and the emergency steering relay 3 is placed in a standby state for energization, such a timer function is not necessarily necessary to achieve the intended purpose of the present invention.
Therefore, a configuration may be adopted in which the timer 7 is removed and only the relay 8 is operated, and the normally open contacts of the relay 8 other than the self-holding contact 8a are used as contacts corresponding to the timer contact 7a in the above embodiment.

As described above, according to the present invention, the engine speed is detected, and when this speed drops to the engine stall precursor speed, the engine stall detection relay is activated, and the electric motor is rotated based on the activation of the relay. This makes it possible to activate the emergency steering pump before the engine actually stalls, thereby improving driving safety by avoiding the dangerous situation where the steering is temporarily unavailable when the engine stalls. It is something that can be improved.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a conventional circuit diagram. DESCRIPTION OF SYMBOLS 1...Emergency steering pump, 2...Electric motor, 3...Emergency steering relay, 4...First contact of the engine stall detection relay, 5...Second contact of the same, 6...Key switch, 8...Relay, 7a...
...Contacts connected in series with the emergency steering relay.

Claims (1)

[Claims] 1 Equipped with power steering, and as a power source for this power steering, a main steering pump for steady driving driven by the engine and an emergency steering pump for when the engine stalls are driven by an electric motor. In a wheel-type working machine configured to be powered on and off by an emergency steering relay, the electric motor detects the engine rotational speed and stops the engine when the rotational speed falls below a predetermined value. an engine rotation speed detection means for emitting a warning signal; a first contact that is controlled by the output signal from the detection means and closes when the engine stall warning signal is input; and a second contact that closes at other times. an engine stall detection relay having a contact; a relay that is energized to form a self-holding circuit when a key switch for starting the engine is turned on and a second contact of the engine stall detection relay is closed; and a contact that closes when the relay is activated. An emergency steering circuit for a wheel-type working machine, characterized in that a series circuit of this contact and a first contact of the engine stall detection relay is connected in series with the emergency steering relay.