JPS627011B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention drives a hydraulic pump using a vehicle running engine, and uses high-pressure hydraulic fluid generated from the hydraulic pump to drive auxiliary equipment mounted on the vehicle, such as a concrete pump. , relates to a hydraulic drive system for vehicle-mounted auxiliary equipment.

For example, in a concrete pump vehicle, power from a driving engine is transmitted to a hydraulic pump via a transmission and a power take-off device, and the hydraulic oil generated by driving this hydraulic pump is supplied to a hydraulic motor. This hydraulic motor drives the mounted concrete pump. When this concrete pump is used to transport fresh concrete to a distant or high location, a large load will be applied to the hydraulic pump, so the gear lever connected to the transmission must be switched to a low speed position. Then, increase the reduction ratio of the transmission so that the hydraulic pump rotates at a low speed, and when delivering ready-mixed concrete to a nearby or low place, switch the gear lever to the high-speed position to increase the hydraulic pressure. The pump is made to rotate at high speed, thereby making effective use of engine output and efficiently pumping fresh concrete.

By the way, the reduction ratio of the transmission is generally 1.33 when the gear shift lever is in the third gear position.
It is 1.00 when it is in the fourth speed position and 0.90 when it is in the fifth speed position, so that the third speed position and the fourth speed position are used to drive the auxiliary equipment. Therefore, if the operator makes a mistake and switches the gear shift lever to the 5th gear position while driving the auxiliary equipment, the rotational speed of the hydraulic pump for driving the auxiliary equipment will become abnormally high, and at that time the auxiliary equipment, that is, the hydraulic pump If the load is high, even if the load is less than the set value, the engine will need to output more than the predetermined output, and the engine will stop. As a result, if the auxiliary equipment is a concrete pump, for example, the concrete pump may be reversed due to the heavy pressure of the fresh concrete that has already been pumped to a high location, causing the danger that the fresh concrete may flow backwards and damage the equipment.

Therefore, the present invention is designed so that when the gear shift lever is switched to a high speed position such as the 5th gear position, or in some cases the 6th gear position, the high pressure hydraulic oil generated by the hydraulic pump is returned to the oil tank. To obtain a hydraulic drive system for vehicle-mounted auxiliary equipment, which allows a hydraulic pump to be driven under almost no load, thereby preventing engine stoppage or equipment damage even if the gear shift lever is erroneously operated. The purpose is to

Next, an embodiment applied to a vehicle-mounted concrete pump of the present invention will be described with reference to FIGS. The drive wheels 3 are driven by the power through the transmission 2 to cause the vehicle to travel. A power take-off device 4 is attached to the transmission 2, and the power of the engine 1 is transmitted through the transmission 2 to the power take-off device 4.
The hydraulic pump 5 is driven by its power. The transmission 2 moves forward 5 by displacing the speed change lever 6 along the speed change panel 7 as shown in FIG.
It is designed to be able to switch from one reverse gear to one reverse gear.

FIG. 3 shows a squeeze-type concrete pump mounted on a vehicle, in which a pumping tube 9 made of an elastic material is bent into a U-shape inside a cylindrical pump case 8 along its inner peripheral surface. Both open ends of the tube 9 protrude outward from the pump case 8, forming a suction side open end and a discharge side open end of the pump. A rotary hydraulic motor 10 is provided at the center of the pump case 8, and the center of an arm 12 is fixed to a drive shaft 11 of the motor. Rollers 13, 13 are rotatably supported at both ends of the arm 12, and the rollers 13, 13 press against the pumping tube 9. Therefore, when the hydraulic motor 10 is operated, the arm 12 rotates, for example, clockwise in FIG.
rolls on the tube 9 while squeezing it, so the tube 9 performs a pumping action due to the squeezing action of the rollers 13 and the restoring force due to its own elasticity.

FIG. 4 shows a hydraulic circuit for operating the hydraulic motor 10 by the hydraulic pump 5. As shown in FIG. A pilot-operated forward/reverse switching valve 14 is interposed in the oil passage between the hydraulic pump 5 and the hydraulic motor 10. This switching valve 14 is connected to the hydraulic pump 5
It has ports 18 and 19 connected to a high-pressure oil passage 15 communicating with the discharge side of the oil tank and a return oil passage 16 communicating with an oil tank 17, respectively, and ports 20 and 21 communicating with two ports of the hydraulic motor 10, respectively. When the system is switched to the central unloading position as shown in the figure, the hydraulic oil sent from the hydraulic pump 5 is transferred to the oil tank 17.
When switching to the forward rotation position on the left side or the reverse rotation position on the right side, the hydraulic oil is guided to one port of the hydraulic motor 10 and discharged from the other port. By doing so, the hydraulic motor 10
It is designed to rotate forward or reverse. The switching operation of the forward/reverse switching valve 14 is performed by switching the pilot hydraulic pressure branched and led from the high pressure oil passage 15 between the hydraulic pump 5 and the switching valve 14 using the operating valve 22 to the left or right side of the switching valve 14. This is done by adding it to the right pilot oil chamber. When no pilot oil pressure is applied to either side, the switching valve 14 automatically returns to the central unloading position by the action of springs S ₁ and S ₁ on both sides. Operation valve 22
is a solenoid-operated switching valve, and in the neutral position shown in the figure, pilot oil pressure is cut off and the pilot oil chambers on both sides of the switching valve 14 are communicated with the oil tank 17. Then, when the left solenoid SOL ₂ is energized, it is switched to the left position and the pilot oil pressure is guided to the left oil chamber of the switching valve 14. When the right solenoid SOL ₃ is energized, it is switched to the right position and the pilot oil pressure is guided to the left side oil chamber. is led to the oil chamber on the right side of the switching valve 14. An oil passage 23 further branches from the high pressure oil passage 15, and a set pressure regulation circuit is connected to this oil passage 23. This set pressure regulation circuit includes a high pressure relief valve 24 and a vent circuit 26 having a set pressure switching valve 25 for remotely changing the set pressure of the high pressure relief valve 24. The high pressure relief valve 24 controls the amount of hydraulic oil that is diverted from the high pressure oil path 15 through the oil path 23.
It controls the oil pressure of the hydraulic oil flowing through the high-pressure oil passage 15, and the drained oil from the relief valve 24 is returned to the oil tank 17 through the return oil passage 16. The set pressure switching valve 25 is a valve that is switched by the solenoid SOL ₁ to open and close the vent circuit 26. When the solenoid SOL ₁ is not energized, it is in the right position as shown in the figure and opens the vent circuit 26. When the solenoid SOL ₁ is energized, it is switched to the left position and the vent circuit 26 is cut off. Switching valve 25
A vent relief valve 27 set at a pressure lower than the maximum set pressure of the high pressure relief valve 24 is connected to the outlet side port of the vent relief valve 27, and the hydraulic oil passing through this relief valve 27 is discharged to an oil reservoir 28. It is becoming more and more like this. When the switching valve 25 is in the right position as shown in the figure, the diverted oil flowing through the oil passage 23 is discharged from the vent relief valve 27 to the oil reservoir 28 through the vent circuit 26, and the set pressure of the high pressure relief valve 24 is set to the vent relief. It comes to work at the set pressure value of the valve 27, and
When the switching valve 25 is switched to the left position,
The diversion of hydraulic oil to the vent circuit 26 is cut off,
The set pressure of the high pressure relief valve 24 is adapted to operate at a predetermined set pressure value of the high pressure relief valve 24.

The set pressure switching valve 25 is configured to be switched in conjunction with the operation of a speed change lever 6 (FIG. 1) that changes the rotation speed of the hydraulic pump 5. Therefore, in this embodiment, limit switches 29 and 30 are provided at the third and fourth speed positions of the speed change panel 7, respectively, as shown in FIG.
When the speed change lever 6 is set to any of these positions, the limit switch 29 or 30 is operated to control the solenoid SOL ₁ of the switching valve 25. The electric circuit for controlling the solenoid SOL ₁ and the solenoids SOL ₂ and SOL ₃ of the operation valve 22 will be explained with reference to FIG.
1 is connected to a main circuit 33 via an ignition switch 32. This main circuit 33 includes
A set pressure control circuit 34 and a forward/reverse switching circuit 35 are connected in parallel. Set pressure control circuit 34
is a circuit in which limit switch 29 and solenoid SOL ₁ are connected in series, and limit switch 2
When solenoid SOL 9 is connected, solenoid SOL ₁ is energized. In the forward/reverse switching circuit 35, a limit switch 30 and a forward/reverse switching switch 36 are connected in series, and solenoids SOL ₂ and SOL ₃ are disposed in parallel with this switching switch 36, so that the switching switch 36 can be switched between forward and reverse rotation. Solenoid by switching to position or reverse position
SOL ₂ or SOL ₃ can be energized, respectively. Furthermore, a diode 37 is connected between the limit switch 29 and the forward/reverse changeover switch 36.
connected via.

In the above embodiment, in order to drive the concrete pump, first, the ignition switch 32 is turned on.
and start engine 1. When transporting fresh concrete to low-lying areas or nearby areas,
Operate the gear shift lever 6 to set it to the fourth gear position. In the fourth speed position, the transmission 2 is switched to a reduction ratio of 1.00, so that the rotational speed of the hydraulic pump 5 driven via the power take-off device 4 is high, and therefore its discharge amount is large. At this time, the limit switch 30 provided at the fourth speed position of the speed change panel 7 becomes "closed". Here, when the forward/reverse changeover switch 36 is operated to switch to the normal rotation position, the solenoid SOL ₂ on the left side of the operating valve 22 is energized, and the operating valve 22 is switched to the left position. Therefore, the hydraulic pressure generated in the high pressure oil passage 15 is guided to the pilot oil chamber on the left side of the forward/reverse switching valve 14, and switches the switching valve 14 to the left normal rotation position. In this way, the hydraulic motor 10 is rotated in the normal direction, and this hydraulic motor 10 drives the concrete pump. At this time, solenoid SOL ₁ of set pressure switching valve 25 is not energized, so switching valve 2
5 is in the position shown in FIG. 4 to open the vent circuit 26. As a result, the high pressure relief valve 24 operates at the set pressure of the vent relief valve 27, which is set to a lower pressure than the high pressure relief valve 24, so the hydraulic pump 5
The pressure of the hydraulic oil supplied to the hydraulic motor 10 through the high-pressure oil passage 15 is maintained relatively low. Therefore, in this case, although the rotational speed of the hydraulic pump 5 is high and the amount of hydraulic oil discharged from the hydraulic pump 5 is large, the pressure of the hydraulic oil is low, so that the output of the engine 1 does not become excessive. In this way, when fresh concrete is pumped to a low place or nearby, the concrete pump is driven at high speed, and a large amount of fresh concrete is pumped in a short time.

Next, when the ready-mixed concrete is to be pumped to a high place or a far place, the speed change lever 6 is set to the third speed position. In the third speed position, the transmission 2 is switched to a reduction ratio of 1.33, so the rotational speed of the hydraulic pump 5 is low, and therefore its discharge amount is also low. At this time, the limit switch 29 at the third speed position is turned on, and the solenoid SOL ₁ of the set pressure switching valve 25 is energized. on the other hand,
The limit switch 30 is turned off, but the limit switch 29 is turned on, so the power supply 3
Current from 1 flows through diode 37 and energizes solenoid SOL ₂ when transfer switch 36 is in the forward position. Therefore, the forward/reverse switching valve 14 is held at the normal rotation position, and the hydraulic motor 10 continues to rotate in the normal rotation. However, at this time, the solenoid SOL ₁ of the set pressure switching valve 25 is energized and the switching valve 25 is switched to the left position, so that the vent circuit 26 is cut off. As a result, the high-pressure relief valve 24 operates at a predetermined maximum set pressure, and the pressure of the hydraulic oil flowing through the high-pressure oil passage 15 increases to the maximum set pressure value defined by the relief valve 24. That is,
Since the hydraulic motor 10 is operated with high-pressure hydraulic oil, the concrete pump driven by the hydraulic motor 10 can pump fresh concrete to a high place or a far place. Moreover, in this case, since the rotational speed of the hydraulic pump 5 is set low, excessive engine output is not required.

When the forward/reverse changeover switch 36 is set to the reverse position, the solenoid _SOL3 on the right side of the operating valve 22 is energized, thereby switching the forward/reverse changeover valve 14 to the right reverse position. This causes the hydraulic motor 10 to rotate in reverse, driving the concrete pump in reverse.

The operator mistakenly moved the gear shift lever 6 to the fifth position.
When switching to the high speed position, the limit switch 29,
30 are both "disconnected", solenoid SOL ₁ ,
Power to both SOL ₂ and SOL ₃ is cut off. When the solenoids SOL ₂ and SOL ₃ of the operating valve 22 are demagnetized in this way, the operating valve 22 returns to the neutral position,
Pilot oil chambers on both left and right sides of the forward/reverse switching valve 14 are communicated with an oil tank 17. Therefore, the switching valve 14 automatically returns to the central unloading position by the action of the springs S ₁ and S ₁ , and the hydraulic pump 5
The hydraulic oil is returned to the oil tank 17 via the high-pressure oil line 15, the switching valve 14, and the return oil line 16. Therefore, the hydraulic pump 5 is driven with almost no load, and the engine 1 will not be stopped even if it rotates at high speed.

Another embodiment of the present invention will be described with reference to FIGS. 6 to 8. The oil passage between the hydraulic pump 5 and the hydraulic motor 10, similar to the embodiment shown in FIGS. A forward/reverse switching valve 38 is provided. This switching valve 38, like the switching valve 14 of the previous embodiment,
In the illustrated central position, the hydraulic oil sent from the hydraulic pump 5 is returned to the oil tank 17 and the hydraulic motor 10 is locked.
When switching to the forward rotation position on the left side or the reverse rotation position on the right side, hydraulic oil is introduced into one port of the hydraulic motor 10 and discharged from the other port, thereby causing the hydraulic motor 10 to rotate forward or reverse. .

Furthermore, a solenoid-operated unload switching valve 39 is provided in the oil passage between the hydraulic pump 5 and this switching valve 38. When the solenoid SOL ₄ is not energized, the switching valve 39 is held in the right position as shown in the figure by the action of the spring S ₂ , and the operating oil from the hydraulic pump 5 is transferred to the forward/reverse switching valve 3 .
When the solenoid SOL ₄ is energized, it is switched to the unload position on the left side, and the drained oil from the hydraulic pump 5 is guided to the oil tank 17. The hydraulic oil sent is returned to the oil tank 17, and the oil passage on the forward/reverse switching valve 38 side is shut off. The oil pressure on the discharge side of the hydraulic pump 5 is kept constant by a relief valve 40.

The speed change lever 6 that switches the transmission to change the rotational speed of the hydraulic pump 5 is
It is designed to be set along a speed change panel 41 as shown in FIG. This speed change panel 41
is provided with a limit switch 42 that is activated when the gear shift lever 6 is set to a switching position that rotates the hydraulic pump 5 at a speed higher than a predetermined rotational speed, for example, the fifth speed position. As shown in FIG. 8, this limit switch 42 is connected in series with the solenoid SOL ₄ of the unload switching valve 39, and when it is actuated by the shift lever 6 and becomes "connected", this solenoid SOL ₄ is energized. It is becoming more and more like this.

Here, when the gear shift lever 6 is operated and set to any of the 1st to 4th speed positions, the hydraulic pump 5
is driven at a corresponding rotation speed. and,
When the forward/reverse switching valve 38 is manually operated to switch to the forward rotation position on the left side or the reverse rotation position on the right side, the hydraulic oil pressurized and supplied by the hydraulic pump 5 is guided to the hydraulic motor 10, and the hydraulic motor 10 is switched to the normal rotation position. It rotates or reverses to drive auxiliary equipment.

At this time, if the operator erroneously operates the shift lever 6 and switches to the fifth speed position, the hydraulic pump 5 rotates at a high speed. However, at this time, the shift lever 6 operates the limit switch 42, so the solenoid of the unload switching valve 39
SOL ₄ is energized and switches this switching valve 39 to the left unload position. As a result, the hydraulic oil from the hydraulic pump 5 is immediately returned to the oil tank 17 by the switching valve 39. Therefore, the hydraulic pump 5 is driven under no load, and even if it rotates at high speed, the engine will not be required to provide excessive output. In particular, in the case of this embodiment, the unload switching valve 3 is located near the hydraulic pump 5.
9, it is possible to reduce the conduit resistance during unloading.

In this embodiment, a normally open limit switch 4 is used.
2 is used so that the solenoid SOL ₄ is energized when this limit switch is closed by the speed change lever 6, and the switching valve 39 is switched to the unload position by the energization of the solenoid SOL ₄ . Instead of this, the limit switch is of a normally closed type, and when the gear shift lever is set to the fifth gear position, the limit switch opens to cut off the power to the solenoid, and when the unload switching valve is thereby restored, It is also possible to switch to the unload position.

In all of the above embodiments, the limit switches 29, 30, 42 and the SOL ₂ , SOL ₃ and SOL ₄ are used, but if these switching valves 14 and 39 can be disposed near the shift lever 6, this interlocking device can be installed at a predetermined position of the shift lever 6. It can also be a purely mechanical device such as an operating rod that is actuated by the actuator, or it can even be constructed solely of a hydraulic device. Also, transmission 2 is the first to fifth transmission.
In the case of something that can be switched faster than
All switching positions for rotating the hydraulic pump 5 at a speed higher than a predetermined rotational speed, for example, the 5th speed position, the 6th speed position,
It is also possible to switch the switching valves 14, 39 to the unload position at the speed position, . . . . In that case, if the hydraulic pump 5 has to be unloaded at many positions, the embodiments shown in FIGS. Embodiments such as those shown in FIGS. 1 to 8 are suitable.

As described above, according to the present invention, the hydraulic pump is driven by the power from the vehicle running engine via the transmission, and its rotational speed is switched by the transmission to maintain an appropriate amount of oil. Since the hydraulic motor is activated to drive the vehicle-mounted auxiliary equipment, the constant engine output can be used most effectively to drive the auxiliary equipment efficiently, and the hydraulic pump is operated at a specified speed or higher. When the hydraulic pump is driven at a speed of This results in a hydraulic drive system of 1.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a drive device for a hydraulic pump used in the device of the present invention, FIG. 2 is a schematic plan view of a speed change panel for setting a speed change lever of the device, and FIG.
The figure is a side view showing a concrete pump as an example of auxiliary equipment in which the device of the present invention is used, FIG. 4 is a hydraulic circuit diagram showing one embodiment of the device of the present invention, and FIG. A circuit diagram showing the electrical system,
Fig. 6 is a hydraulic circuit diagram showing another embodiment of the device of the present invention, Fig. 7 is a schematic plan view of a speed change panel used in the device of Fig. 6, and Fig. 8 is an electric circuit diagram used in the device of Fig. 6. It is a circuit diagram showing a system. S ₁ , S ₂ ... Spring, SOL ₂ , SOL ₃ , SOL ₄
... Solenoid, 1 ... Vehicle running engine, 2
...Transmission, 5...Hydraulic pump, 6
... Speed lever, 7 ... Speed change panel, 10 ... Hydraulic motor, 14 ... Forward/reverse switching valve, 15 ... High pressure oil path, 16 ... Return oil path, 17 ... Oil tank, 22 ... Operation valve , 29, 30... Limit switch, 39... Unload switching valve, 41... Speed change panel, 42... Limit switch.

Claims (1)

[Scope of Claims] 1. A hydraulic pump driven by power taken out from the vehicle running engine via the transmission; operated by hydraulic fluid from the hydraulic pump to drive vehicle-mounted auxiliary equipment such as a concrete pump. a hydraulic motor that switches the transmission; a switching valve that is provided in an oil passage between the hydraulic pump and the hydraulic motor and has an unload position that allows hydraulic oil from the hydraulic pump to flow back to the oil tank; a gear shift lever that switches the transmission; A hydraulic drive device for vehicle-mounted auxiliary machinery, comprising an interlocking device that switches the switching valve to an unloading position when the hydraulic pump is operated to a switching position that rotates the hydraulic pump at a speed higher than a predetermined rotational speed. 2. The interlocking device includes a limit switch that operates when the speed change lever is in a switching position that rotates the hydraulic pump at a predetermined rotational speed, and a solenoid that is energized by the operation of the limit switch. A hydraulic drive system for a vehicle-mounted auxiliary machine according to claim 1, which is an automatic return type switching valve that returns to an unloading position when not energized. 3. A limit switch in which the interlocking device operates when the speed change lever is in a switching position that rotates the hydraulic pump at a speed equal to or higher than a predetermined rotation speed;
A hydraulic drive system for a vehicle-mounted auxiliary machine according to claim 1, comprising a solenoid that switches the switching valve to an unload position by the operation of the limit switch.