JP2000229509A - Vehicular height adjusting device for wheel shovel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily set each part relating to a suspension performance in a wheel shovel which has a vehicular height adjustable suspension system. SOLUTION: A link 4 and right and left cylinders 2 are provided between an axle 1 and a flame, and oil chambers 2b, 2c of each cylinder 2 communicate with each other through an accumulator 7. The oil chambers 2b, 2c of each cylinder 2 are connected to a hydraulic source 13 via a directional switching valve 8 and a hydraulic pilot switching valve 12, and the directional switching valve 8 is switched by manual operation while the hydraulic pilot switching valve 12 is switched according to operation of a gate lock lever 86 and a brake switch. Each part (for example, a restrictor 5a, 5b, 6a) can be thereby easily set since a pressure oil can be supplied from the hydraulic source 13 to each cylinder 2 only when a parking brake operates and the gate lock lever 86 is released, resulting that vehicular height is not adjusted in traveling or working of a vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle height adjusting device for a wheel shovel that moves on wheels with tires.

[0002]

2. Description of the Related Art In recent years, work vehicles moving with wheels with tires, such as wheel shovels, have tended to travel at high speeds. In order to further improve the ride comfort of an operator at high speed travel, for example, Japanese Patent Application Laid-Open No. 7-132723. The publication discloses an apparatus in which a suspension mechanism is provided between a vehicle body and an axle. According to this device, a hydraulic cylinder connected to the accumulator and the throttle is provided between the vehicle body and the axle, and the hydraulic cylinder is controlled so that the distance between the axle and the vehicle body during traveling or work becomes a predetermined value set in advance. Control pressure. This absorbs vibrations during driving,
In addition to being able to attenuate, the attitude of the work vehicle can always be kept horizontal regardless of the size of the work device attached to the work vehicle.

[0003]

However, in the device described in the above publication, suspension performance is exhibited while controlling the pressure of the hydraulic cylinder during traveling, so that it is difficult to set various parts (such as the throttle) related to suspension performance. Also, since the pressure of the hydraulic cylinder is controlled during the operation, the suspension becomes fluffy and the operator feels strange.

[0004] It is an object of the present invention to provide a vehicle height adjusting device for a wheel shovel, which facilitates setting of various parts relating to suspension performance and can always obtain proper suspension performance.

[0005]

FIG. 2 shows an embodiment of the present invention.
This will be described with reference to FIGS. (1) The first aspect of the present invention is directed to each of the hydraulic cylinders 2 connected to at least one of the left and right sides of the axle 1 provided on the front and rear of the vehicle and the vehicle body 87 and the oil chambers 2b and 2c of each of the hydraulic cylinders 2 respectively. The present invention is applied to a wheel shovel provided with a suspension having an accumulator 7 communicated with the diaphragms 5a, 5b, 6a. Cylinder expansion / contraction means 8, 31 for supplying hydraulic oil to each hydraulic cylinder 2 and discharging hydraulic oil from each hydraulic cylinder 2 to expand and contract each hydraulic cylinder 2, and traveling for detecting the traveling / non-traveling state of the vehicle When the non-traveling state is detected by the detecting means 21 and the traveling detecting means 21, the hydraulic cylinders 2 are allowed to expand and contract by the cylinder extending / contracting means 8 and 31. Telescopic means 8, 31
Control means 12, 14, 1 for prohibiting expansion and contraction of each hydraulic cylinder 2 due to the above, so as to exert a suspension function.
By providing 7, 18, 21, 24-26, 30, the above-mentioned object is achieved. (2) The invention according to claim 2 further includes work detection means (86), 86a for detecting a work / non-work state of the vehicle,
Control means 12, 14, 17, 18, 21, 24-26, 30
When the non-working state is detected by the work detection means (86), 86a, the hydraulic cylinders 2 are allowed to expand and contract by the cylinder expansion and contraction means 8, 31, and the work detection means (86), 8a
When the work state is detected by 6a, the expansion and contraction of each hydraulic cylinder 2 by the cylinder expansion and contraction means 8, 31 is prohibited. (3) The invention of claim 3 is that the traveling detecting means 21 detects the traveling / non-traveling state based on the vehicle speed or the braking state. (4) As shown in FIG. 1, the invention according to claim 4 is a release position (A) for preventing the occupant from getting on and off in the route where the occupant gets on and off the driver's cab 85, and a lock position ( B) a gate lock lever 86 operated by the user, and a work / non-work control means for permitting the work when the gate lock lever 86 is at the release position (A) and prohibiting the work when it is at the lock position (B). The work detecting means (86), 86a detects work when the gate lock lever 86 is at the release position (A), and detects non-work when the gate lock lever 86 is at the lock position (B). Is what you do.

[0006] In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used to make the present invention easy to understand. However, the present invention is not limited to this.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a side view (partially sectional view) of a wheel shovel to which the present invention is applied. As shown in FIG. 1, the wheel shovel includes a lower traveling body 81 and an upper revolving body 83 that is pivotally connected to an upper portion of the lower traveling body 81 via a pivoting device 82. The upper revolving unit 83 is provided with a work front attachment 84 (hereinafter, referred to as an attachment) including a boom 84A, an arm 84B, and a bucket 84C, and an operator's cab 85. A gate lock lever 86 is provided at the release position (A position) to be operated to the lock position (B position) when getting off the vehicle. In the lower traveling body 81,
A chassis frame 87 (hereinafter, referred to as a frame), a traveling hydraulic motor 88, a transmission 89, a propeller shaft 90, and a tire 91 are provided. The driving force from the propeller shaft 90 is transmitted to the tire 91 via the axles 1, 1 '. Is transmitted to In the present embodiment, the rear axle 1 'is directly fixed to the frame 87, and the front axle 1 is connected to the frame 87 via the following suspension mechanism.

FIG. 2 is a front view of a wheel shovel to which the present invention is applied (A view in FIG. 1), and mainly shows a configuration of a suspension mechanism. As shown in FIG. 2, a cylinder block 3 having a telescopic cylinder 2 is mounted on each of the left and right ends of the frame. The tip of a piston rod 2a is rotatably connected to the axle 1 via a pin 92. Have been. One end of the link 4 is rotatably connected to one of the left and right ends (left side in the figure) of the frame 87 via a pin 93, and the other end passes through an opening 87a provided at the bottom of the frame 87. And reaches the center of the axle 1 (on the center line CL), and is rotatably connected via a pin 94. As a result, the link 4 rotates as shown by the arrow with the pin 93 as a fulcrum, and the piston rod 2
The axle 1 mainly moves up and down with respect to the frame 87 within the range of expansion and contraction of a. Further, in some cases, the axle 1 is supported by the pin 94 as a fulcrum within the range of expansion and contraction of the piston rod 2a.
Rocks.

FIG. 3 is a bottom view of a wheel shovel to which the present invention is applied (a view B in FIG. 1), and mainly shows the arrangement of hydraulic piping. The axle 1 in FIG.
Is not shown. As shown in FIG. 3, the left and right cylinder blocks 3 are connected through a pipe 5, and an accumulator 7 is connected in the middle of the pipe 5 through a pipe 6. The accumulator 7 further includes a direction switching valve 8 whose position is switched by manual operation of a switching lever 8a.
Are connected via a pipe 9, and the direction switching valve 8 is connected to a center joint 11 via a pipe 10.

FIG. 4 is a hydraulic circuit diagram showing the configuration of the vehicle height adjusting device according to the first embodiment of the present invention. As shown in FIG. 4, the accumulator 7 is provided with the directional control valve 8 described above.
And a center joint 11, and further connected to a main hydraulic source 13 via a hydraulic pilot switching valve 12. Pilot port 12 of hydraulic pilot switching valve 12
a is connected to a pilot hydraulic pressure source 16 via an electromagnetic switching valve 14 and a lock valve 15. The position of the lock valve 15 is switched by operating a gate lock lever 86 provided in the cab 85. That is, when the gate lock lever 86 is operated to the release position, the position (a)
Is switched to, and when operated to the lock position,
Is switched to. The solenoid-operated switching valve 14 is at a position (b) when the solenoid 14a is excited by an electric signal I described later, and at a position (a) when the solenoid 14a is demagnetized.
Respectively.

When both the lock valve 15 and the electromagnetic switching valve 14 are switched to the position (B), the pilot pressure from the pilot hydraulic pressure source 16 is supplied to the pilot port 12a of the hydraulic pilot switching valve 12, and the hydraulic pilot switching valve 12 Is switched to the position (b). Thereby, the pressure oil from the main hydraulic pressure source 13 is supplied to the direction switching valve 8. When at least one of the lock valve 15 and the electromagnetic switching valve 14 is switched to the position (A), the pilot port 12a of the hydraulic pilot switching valve 12 is connected to the tank, and the hydraulic pilot switching valve 12 is switched to the position (A). Can be As a result, the supply of the pressure oil to the direction switching valve 8 is stopped, and the adjustment of the vehicle height is prohibited.

The directional control valve 8 is a three-port, three-position directional control valve, for example, a ball valve as shown in FIG. When the directional control valve 8 is switched to the position (a), the A port communicates with the P port, and when switched to the position (c), the A port communicates with the T port. When the position is switched to the position (b), the A port is completely blocked from the P port and the T port as shown in FIG. 5, that is, the leak amount from the A port becomes zero.

As shown in FIG. 4, a throttle 6a having an area A1 is provided in a pipe 6 connected to the accumulator 7, and an area A2 is provided in a pipe 5 communicating the pair of cylinder blocks 3 respectively.
Apertures 5a are provided, and these apertures 5a, 6
At least a has a relationship of A1> A2. Therefore, when the cylinder 2 contracts and high-pressure oil is supplied into the pipeline 5, the pressure oil is accumulated in the accumulator 7 through the throttles 5a and 6a, and the accumulated pressure oil returns the vehicle body to the neutral position. Is supplied to each of the cylinders 2. In this case, the accumulator 7 mainly functions as a spring for absorbing vibration, and the diaphragms 5a and 6a as resistors mainly function as dampers for attenuating vibration. The characteristics of these springs and dampers are determined by the gas pressure sealed in the accumulator 7 and the areas of the throttles 5a and 6a.

The pipe line 5 is branched into two parts in the cylinder block 3, one of which is connected to the bottom chamber 2 b of the cylinder 2 via a pilot check valve 17, and the other of which has an area A 3 (<
A1) is connected to the rod chamber 2c of the cylinder 2 via the throttle 5b and the pilot check valve 17. The pilot port of the pilot check valve 17 is an electromagnetic switching valve 18
The driving of the pilot check valve 17 is controlled by switching the electromagnetic switching valve 18 through the pilot hydraulic pressure source 16. The electromagnetic switching valve 18 is at a position (b) when the solenoid 18a is excited by an electric signal I described later, and at a position (a) when the solenoid 18a is demagnetized.
Respectively.

When the electromagnetic switching valve 18 is switched to the position (b), the pressure oil from the pilot hydraulic pressure source 16 is supplied to the pilot port of the pilot check valve 17. As a result, the pilot check valve 17 functions simply as an opening valve, and the movement of the pressure oil from the oil chambers 2b and 2c of each cylinder 2 becomes possible (an unlocked state). At this time, the flow of the pressure oil in the bottom chamber 2b and the rod chamber 2c is restricted by the throttle 5b.
That is, the diaphragm 5b mainly functions as a damper for damping vibration. When the electromagnetic switching valve 18 is switched to the position (a), the supply of the pressure oil from the pilot hydraulic pressure source 16 is stopped, whereby the pilot check valve 17 functions as a normal check valve and the oil chamber of each cylinder 2 The movement of the pressure oil from 2b and 2c is prohibited (locked state).

FIG. 6 is an electric circuit diagram of the vehicle height adjusting device according to the first embodiment. As shown in FIG. 6, the electric circuit has a T-contact 21 corresponding to each mode of traveling, parking, and work.
A brake switch 21 that can be switched between a T, P contact 21P and a W contact 21W; a vehicle height adjustment switch 22 for commanding a vehicle height adjustment by operation from a driver's cab 85;
And the relays 24, 25, 26 constitute a relay circuit. The relay circuit electrically connects the solenoids 14a, 18a of the electromagnetic switching valves 14, 18, the solenoid 27 for releasing the parking brake, and the solenoid 28 for operating the work brake. The supply of the signal I is respectively controlled.

Referring to FIG. 6 in detail, the brake switch 21
The common contact 21s is connected to the power supply 23, the T contact 21T is connected to the a contact 24a of the relay 24, the coil 25c of the relay 25 and the solenoid 27 for releasing the parking brake, and the W contact 21W is connected to the coil 26c of the relay 26 and the work brake. Each of them is connected to a solenoid 28, and the P contact 21P is open. When the brake switch 21 is switched to the W contact 21W side and the solenoid 28 for operating the work brake is excited, the work brake is operated and the brake switch 21 is turned on.
Is switched to the P contact 21P side or the W contact 21W side, and the parking brake is activated when the solenoid 27 for releasing the parking brake is demagnetized. The work brake and the parking brake are well-known, and their illustration is omitted.

The solenoid 18a of the electromagnetic switching valve 18 is connected to a common contact 24s of the relay 24 and a b contact 24b of the relay 24.
Is connected to the a contact 26a of the relay 26, and the common contact 26s of the relay 26 is connected to the power source 23, respectively.
The contact 26b is open. The solenoid 14 a of the electromagnetic switching valve 14 is connected to the vehicle height adjustment switch 22, the vehicle height adjustment switch 22 is connected to the a contact 25 a of the relay 25,
The 5 common contacts 25s are respectively connected to the power supply 23, and the b contact 25b of the relay 25 is open. Therefore, the brake switch 21 is set to the P contact 21P side or W
When the contact is switched to the contact 21W side, the relay 25
5a, and in this state the vehicle height adjustment switch 2
2 is turned on, the solenoid 14a of the electromagnetic switching valve 14
Is connected to the power supply 23 and is excited. When the brake switch 21 is switched to the P contact 21P side and the vehicle height adjustment switch 22 is turned on, the relays 24 and 26 are switched to the b contact 24b side and the a contact 26a side, respectively. The solenoid 18a is connected to the power supply 23 and is excited. Further, when the brake switch 21 is switched to the T contact 21T side, the relay 24 is switched to the a contact 24a side, and the electromagnetic switching valve 18
The solenoid 18a is connected to the power supply 23 and is excited.

Next, the operation of the vehicle height adjusting apparatus according to the first embodiment will be described more specifically. (1) Running Mode In the running mode, the brake switch 21 is switched to the T contact 21T side as shown in FIG. As a result, the solenoid 28 for operating the work brake is demagnetized to release the work brake, and the solenoid 27 for releasing the parking brake is excited to release the parking brake. Further, the coil 25c of the relay 25 is energized, and the relay 25 is switched to the b contact 25b side, whereby the circuit to the solenoid 14a of the electromagnetic switching valve 14 is cut off, the solenoid 14a is demagnetized, and the electromagnetic switching valve 14
Is the position (a). Further, the coil 26 of the relay 26
c, the circuit of the relay 26 is switched to the a contact 26a, the circuit of the relay 24 to the coil 24c is disconnected, the relay 24 is switched to the a contact 24a, and the solenoid 18a is energized to Switching valve 1
8 is the position (b). The demagnetization of the solenoid 14a and the excitation of the solenoid 18a in the traveling mode are independent of the operation of the vehicle height adjustment switch 22.

In the hydraulic circuit of FIG. 4, when the solenoid 14a is demagnetized as described above, the electromagnetic switching valve 14 is switched to the position (a), and the pilot port 12a of the hydraulic pilot switching valve 12 is connected to the tank. Thereby, the hydraulic pilot switching valve 12 is switched to the position (a), and the P port of the direction switching valve 8 is communicated with the tank. As described above, when the solenoid 18a is excited, the electromagnetic switching valve 18 is switched to the position (b), and the hydraulic oil from the pilot hydraulic pressure source 16 receives the pilot check valve 1
7 pilot ports. Thereby, the pilot check valve 17 functions as a simple opening valve,
The movement of the pressure oil between the bottom chamber 2b and the rod chamber 2c of each cylinder 2 and between the accumulator 7 becomes possible. In addition,
In the traveling mode, the direction switching valve 8 is manually operated by the switching lever 8a provided below the frame 87 so that the direction switching valve 8 is turned on as shown in FIG.
, The switching lever 8 is not operated during traveling, so that the inflow and outflow of pressure oil from the direction switching valve 8 is prevented.

In such a running mode, for example, when the work vehicle is running at high speed, a high cycle vibration is generated by the tire 91 and the axle 1 due to the unevenness of the road surface.
a, a part of the pressure oil (dynamic pressure oil) from the high pressure side cylinder 2 (the contracting cylinder) moves to the accumulator 7 via the throttles 5a and 6a, After being accumulated in the accumulator 7, the pressure is supplied to each cylinder 2 so as to return the vehicle body to the neutral position. At this time,
The accumulator 7 functions as a spring for absorbing the vibration of the piston rod 2a, and the higher the gas pressure of the accumulator 7, the harder the suspension. Also, the apertures 5a, 5b,
6a functions as a damper for restricting the transmission of vibration, and the smaller the throttle, the harder the stroke of the cylinder 2 and the greater the damping. Due to the expansion and contraction of the cylinder 2 accompanying the movement of the pressurized oil, the axle 1 moves up and down or swings with respect to the frame 87. Is prevented from being transmitted directly to the frame 87. In this case, when the left and right cylinders 2 expand and contract in the same direction, for example, when both left and right tires 91 receive external force in the same direction, the axle 1 moves up and down, and only one of the left and right tires applies external force. When the left and right cylinders 2 expand and contract in opposite directions, for example, when received, the axle 1 swings.

When a low cycle vibration is input to the piston rod 2a due to the unevenness of the road surface when the work vehicle is running at low speed, the hydraulic oil (static pressure) is transferred from the high pressure side cylinder 2 to the low pressure side cylinder 2. Oil) is supplied, and the pressure of each cylinder 2 becomes equal. Thereby, even if the road surface has irregularities, the contact pressure of the tire 91 can be kept equal, and the stability of the work vehicle can be improved. On the other hand, when the work vehicle is stopped, the pressure of each cylinder 2 becomes equal, the flow of the pressure oil stops, and the gravity W from the attachment 84 and the force F acting on the piston 2p in the cylinder 2 are balanced (W). = F), the cylinder 2 stops. In this case, the force F acting on the piston 2p is represented by S1 as the pressure receiving area of the piston 2p on the bottom chamber 2 side, S2 as the pressure receiving area of the piston 2p on the rod chamber 2c side, and P2 as the pressure in the cylinder 2.
Then, F = P × (S1−S2).

(2) Parking Mode In the parking mode, the brake switch 21 is switched to the P contact 21P as shown in FIG. Thereby, the solenoid 27 for releasing the parking brake and the solenoid 28 for operating the work brake are both demagnetized, the parking brake is operated, and the work brake is released. here,
When the vehicle height adjustment switch 22 is turned off (opened), the solenoid 14a of the electromagnetic switching valve 14 is demagnetized, and the circuit to the coil 24c of the relay 24 is cut off.
Is switched to the a contact 24a side, and the solenoid 18a of the electromagnetic switching valve 18 is demagnetized.

As shown in FIG. 4, the solenoids 14a, 1
When 8a is demagnetized, both of the electromagnetic switching valves 14, 18 are switched to the position (a). As a result, the hydraulic pilot switching valve 12 is switched to the position (A), the P port of the direction control valve 8 is communicated with the tank, and the supply of pressure oil to the pilot port of the pilot check valve 17 is stopped. The check valve 17 functions as a check valve, and the movement of the pressure oil from the oil chambers 2b and 2c of each cylinder 2 is prohibited.

In this embodiment, the vehicle height can be adjusted to a desired height position depending on the type of the attachment 84 used, but this adjustment is performed in the parking mode. Hereinafter, the adjustment of the height position (vehicle height adjustment) will be described. As an initial condition, an attachment 84 having a standard weight w is mounted, and as shown in FIG. 7A, positions where the strokes L1 and L2 in the contraction direction and the extension direction of the cylinder 2 are equal to each other (L1 = L2). And the piston 2p is stationary. Here, as shown in FIG.
When the attachment 84 'is replaced with (> W), the cylinder 2 contracts, the front vehicle height decreases, and the stroke allowable amount L1' in the contraction direction decreases (L1 '<L1). Also,
As shown in FIG. 7C, when the attachment 84 ″ is replaced with an attachment 84 ″ having a weight W ″ (<W), the cylinder 2 is extended, the front vehicle height is increased, and the stroke possible amount L2 ″ in the extending direction is increased.
Becomes smaller (L2 ″ <L2). When the attachment 84 is replaced in this manner, the vehicle height becomes lower or higher, and the stroke possible amount L1 ″, L2 ″ in the contraction direction or the extension direction is obtained.
And the suspension function cannot be fully demonstrated, resulting in poor ride comfort. In order to prevent this, the vehicle height is adjusted, and when the attachment 84 is replaced, the vehicle height is maintained at an appropriate value (for example, L1 ′ = L2 ′, L1 ″ = L2 ″).

As shown in FIG. 6, since the brake switch 21 is switched to the P contact 21P in the parking mode, the coils 25c and 26c of the relays 25 and 26 are not energized, and the relays 25 and 26 are respectively connected to the a contacts 25a and 26a. Side. Here, when the vehicle height adjustment switch 22 is turned on (closed) to perform vehicle height adjustment, the electromagnetic switching valve 1
4 is energized and the relay 2
No. 4 coil 24c is energized and relay 24 is switched to contact b
The solenoid 18 of the electromagnetic switching valve 18 is switched to the b side.
a is excited.

As shown in FIG. 4, the solenoids 14a, 1
When the magnet 8a is excited, the electromagnetic switching valves 14 and 18 are both switched to the position (b). When the vehicle height is adjusted, the gate lock lever 86 is locked and the lock valve 15 is switched to the position (b). As a result, the hydraulic oil from the pilot hydraulic source 16 is supplied to the hydraulic pilot switching valve 1
And the hydraulic pilot switching valve 12 is switched to the position (b).
Pressure oil from the pilot hydraulic pressure source 16 is supplied to a pilot port of a pilot check valve 17, and the pilot check valve 17 is an open valve.

Here, for example, when the cylinder 2 is in the state shown in FIG. 7B (L1 '<2') and the cylinder 2 is extended in order to make L1 '= L2', the switching lever 8a must be turned on. Operate to switch the direction switching valve 8 to the position (a). Then, the pressure oil from the main oil pressure source 13 is supplied to the oil chambers 2b and 2c of each cylinder 2 via the direction switching valve 8, respectively.
Accordingly, the force F (force in the extension direction) acting on the piston 2p increases, the cylinder 2 expands, and the vehicle height increases. Further, the cylinder 2 is in the state shown in FIG.
L2 ''), when the cylinder 2 is contracted in order to set L1 '' = L2 '', the switching lever 8a is operated to switch the direction switching valve 8 to the position (C). Then, the pressure oil from the oil chambers 2b and 2c of each cylinder 2 is discharged to the tank via the tank direction switching valve 8, whereby the force F acting on the piston 2p decreases, the cylinder 2 contracts, and the vehicle height increases. Becomes lower. The vehicle height is adjusted in this manner, and the vehicle height becomes a predetermined value (a value that satisfies L1 ′ = L2 ′, L1 ″ = L2 ″).
Is reached, the switching lever 8a is operated to switch the direction switching valve 8 to the position (b).

(3) Work Mode In the work mode, the brake switch 21 is switched to the W contact 21W side. As a result, the solenoid 28 for operating the work brake is excited, the solenoid 27 for releasing the parking brake is demagnetized, and both the work brake and the parking brake are operated. Further, the coil 25c of the relay 25 is not energized and the relay 25 is switched to the a contact 25a side, and the coil of the relay 26 is energized and the relay 26 is switched to the b contact 26b. Therefore, even if the vehicle height adjustment switch 22 is turned on by mistake and the coil 24c of the relay 24 is energized, the solenoid 18a of the electromagnetic switching valve 18 is not excited, and the electromagnetic switching valve 1 is turned off.
8 is switched to the position (a), and the pilot check valve 17 functions as a check valve. Height adjustment switch 2
2 is erroneously turned on, the solenoid 14a of the electromagnetic switching valve 14 is energized and the electromagnetic switching valve 14 is switched to the position (b). The valve 15 is switched to the position (a). Therefore, no pressure oil is supplied to the pilot port 12a of the hydraulic pilot 12, and the P port of the direction switching valve 8 is connected to the tank. As described above, the pilot check valve 17 functions as a check valve and the P port of the direction switching valve 8a communicates with the tank, so that the movement of the pressure oil from the oil chambers 2b and 2c of each cylinder 2 is prohibited. . As a result, even if the switching lever 8a is operated, the vehicle height does not change.

In the working mode, the pressure oil from the pilot hydraulic pressure source 16 is supplied to the pilot valve via the lock valve 15. Therefore, for example, when the operation lever (not shown) is operated to drive the attachment 84, the operation lever is operated. The pilot pressure oil proportional to the operation amount of the is guided to the pilot control valve, and the control valve is operated.
This enables operations such as excavation. At this time,
Since the movement of the pressure oil from the oil chambers 2b and 2c of each cylinder 2 is prohibited, the cylinder 2 is not stroked and the reaction force due to excavation (excavation reaction force) is not absorbed by the accumulator 7 and the suspension lock state is achieved. Work can be performed stably.

As described above, according to the first embodiment, the switching valves 12, 14, and 15, which are switched in conjunction with the operation of the brake switch 21 and the gate lock lever 86, are provided.
Activate the parking brake and operate the gate lock lever 86
Only when is operated to the lock position (work prohibited state)
That is, the pressure oil is supplied to the P port of the direction switching valve 8 only when the parking mode is selected, and the vehicle height can be adjusted by operating the switching lever 8a. Therefore, the vehicle height is not adjusted during traveling or work. As a result, since it is not necessary to consider the vehicle height adjustment function during traveling, it is easy to set each part relating to the suspension performance, and at the time of work, the check valve 17 controls the pressure from the oil chambers 2b and 2c of the cylinders 2. Because the movement of oil is prohibited, the user can work while feeling the reaction of excavation without feeling uncomfortable. Also, a relay circuit is provided by the brake switch 21 and the relays 24 to 26, and the like.
Even if the vehicle height adjustment switch 22 is erroneously turned on during running or work, or the switching lever 8a is operated during work (cannot be operated during running), the vehicle height adjustment is prohibited (so-called interlock). ), It is possible to prevent undesired vehicle height adjustment. Further, since the vehicle height adjustment during traveling and work is prohibited, the pressure of the cylinder 2 is not frequently controlled by using the pressure oil from the main hydraulic power source 13, so that fuel efficiency is reduced.

-Second Embodiment- FIG. 8 is a hydraulic circuit diagram showing a configuration of a vehicle height adjusting device according to a second embodiment of the present invention. The same parts as those in FIG. 4 are denoted by the same reference numerals, and the differences will be mainly described below. As shown in FIG. 8, the vehicle height adjusting apparatus according to the second embodiment includes a direction switching valve 8, a hydraulic pilot switching valve 12, a lock valve 15, and an electromagnetic switching valve 1 shown in FIG.
4 and an electromagnetic control valve 3 for controlling the flow of hydraulic oil from the main hydraulic pressure source 13 to each cylinder 2 instead of the relay circuit of FIG.
1 and a controller 3 for controlling the drive of the electromagnetic control valve 31
0 and the stroke amounts z1, z2 of the cylinders 2 from the reference position z0 (the state of FIG. 7A in this embodiment).
, And a gate lock switch 86a that is turned on / off in accordance with the release / lock operation of the gate lock lever 86. Although not shown, the brake switch 21 has the same configuration as in FIG.
A solenoid 26 for releasing the parking brake and a solenoid 27 for operating the work brake are connected respectively.

The controller 30 is connected to stroke sensors 32 and 33, a gate lock switch 86a, a brake switch 21, and a vehicle height adjustment switch 22. The controller 30 executes processing described later based on these input signals, and outputs control signals I to the solenoids 31a and 31b of the electromagnetic control valve 31 and the solenoid 18a of the electromagnetic switching valve 18, respectively.

FIG. 9 is a flowchart showing an example of the processing executed by the controller 30. This flowchart is started, for example, by turning on an engine key switch (not shown). First, in step S1, it is determined which of the brake switches 21 has been switched based on a signal from the brake switch 21. If it is determined that the brake switch 21 has been switched to the P contact 21P side, the process proceeds to step S2, and it is determined whether the vehicle height adjustment switch 22 is on. When step S2 is affirmed, the process proceeds to step S3, and when denied, the process proceeds to step S13. In step S3, it is determined whether or not the gate lock switch 86a is ON, that is, whether or not the gate lock lever 86 is locked. When step S3 is affirmed, the process proceeds to step S4, and when denied, the process proceeds to step S11. In step S4, the solenoid 1 of the electromagnetic switching valve 18
The control signal I is output to 8a to excite the solenoid 18a. As a result, the electromagnetic switching valve 18 is switched to the position (b) as shown in FIG.
The pilot port is supplied with pressure oil from a pilot hydraulic pressure source 16 and the pilot check valve 17 functions as an opening valve.

Next, in step S5, the detection values z1, z2 from the stroke sensors 32, 33 are read. In step S6, the average value of the detected values z1, z2 ((z1 + z2)
/ 2), and subtracting it from a preset target value za (for example, 0, that is, a state of L1 = L2) to obtain a deviation a (=
za− (z1 + z2) / 2) is calculated. Next, in step S7, the deviation a is equal to the predetermined upper limit α1 (for example, 1.01 ×
a) It is determined whether or not the value is larger. If the result is affirmative, the process proceeds to step S8. If the result is negative, the process proceeds to step S9. Step S
8, the control signal I is supplied to the solenoid 31a of the electromagnetic control valve 31.
Is output to excite the solenoid 31a, and the process returns to step S5. As a result, the electromagnetic control valve 31 is switched to the position (a), and the pressure oil from the main hydraulic pressure source 13 is supplied to the oil chambers 2b and 2c of each cylinder 2. As a result, the cylinder 2 extends and the vehicle height increases. On the other hand, in step S9, it is determined whether or not the deviation a is smaller than a predetermined lower limit value α2 (for example, 0.99 × a).
If the answer is no, the process proceeds to step S11. Step S1
At 0, the control signal I is supplied to the solenoid 31b of the electromagnetic control valve 31.
Is output to excite the solenoid 31b, and the process returns to step S5. Thereby, the electromagnetic control valve 31 is switched to the position (C), and the pressure oil from each cylinder 2 is discharged to the tank. As a result, the cylinder 2 contracts and the vehicle height decreases. In step S11, the solenoid 3 of the electromagnetic control valve 31
The output of the control signal I to 1a, 31b is stopped, the solenoids 31a, 31b are demagnetized, and the routine returns. As a result, the electromagnetic control valve 31 is switched to the position (b), and the circuit on the cylinder 2 side is blocked from the main hydraulic pressure source 13 and the tank.

In step S1, the brake switch 2
If it is determined that 1 has been switched to the T contact 21T side, the process proceeds to step S12, and the solenoid 18 of the electromagnetic switching valve 18
a to output a control signal I to excite the solenoid 18a,
Proceed to step S11. Thereby, the electromagnetic switching valve 18
Is switched to the position (b) and the pilot check valve 1
The pilot port 7 is supplied with pressure oil from a pilot hydraulic pressure source 16 and the pilot check valve 17 functions as an opening valve. As a result, the oil chambers 2b, 2 of each cylinder 2
The suspension and the accumulator 7 communicate with each other to actuate the suspension (suspension unlocked state) to absorb and attenuate vibrations during traveling. Further, if it is determined in step S1 that the brake switch 21 has been switched to the W contact 21W side, the process proceeds to step S13, in which the output of the control signal I to the solenoid 18a of the electromagnetic switching valve 18 is stopped, and the solenoid 1
8a is demagnetized, and the process proceeds to step S11. by this,
The electromagnetic switching valve 18 is switched to the position (a), the supply of pressure oil to the pilot port of the pilot check valve 17 is stopped, and the pilot check valve 17 functions as a check valve. As a result, the oil chambers 2b, 2c of each cylinder 2
Pressure oil is prohibited from entering and exiting (suspension locked state), and it is possible to counteract excavation reaction force and the like.

The specific operation of the second embodiment is described in that the suspension function of the accumulator 7 is exerted in the traveling mode, the parking brake is operated in the parking mode, and the gate lock lever 8 is operated.
6 that the vehicle height can be adjusted when the lock operation is performed,
And the oil chambers 2b, 2 of each cylinder 2 in the working mode.
Since the basic operation such as blocking of c is the same as that of the first embodiment, the description is omitted.

As described above, according to the second embodiment,
Based on the detection values z1, z2 from the stroke sensors 32, 33, the electromagnetic control valve 3 is controlled by a command from the controller 30.
Since the vehicle height is automatically adjusted by switching 1, the labor of manually operating the directional control valve 8 and the like are omitted, and the efficiency of the vehicle height adjustment operation is improved.

As described above, according to the present invention, the vehicle height can be adjusted during parking, the vehicle height can be adjusted during running and working, and the suspension function can be exhibited during running (suspension unlocking). (Suspension lock), which is not limited to the above-described embodiment, and can be implemented in various forms. For example, in the above-described embodiment, the accumulators 7 are provided so as to communicate with the left and right cylinders 2. However, the accumulators 7 may be separately provided for each cylinder 2. Further, in the above embodiment, the vehicle height adjusting device is provided only on the front wheels, but may be provided only on the rear wheels or on both the front wheels and the rear wheels. Further, in the above-described embodiment, the running, parking, and work states of the vehicle are detected in response to the operation of the brake switch 21, that is, based on the brake state. However, the state is detected by a vehicle speed sensor (not shown) or the like. The vehicle state may be detected based on the value.

In the correspondence between the above-described embodiments and the claims, the direction switching valve 8 and the electromagnetic control valve 31 serve as cylinder expansion / contraction means, the brake switch 21 serves as travel detection means, and the gate lock lever 86 and the gate lock switch 86a serve as cylinders. The work detecting means includes the hydraulic pilot switching valve 12 and the electromagnetic switching valve 1
4, 18, the pilot check valve 17, the brake switch 21, the relays 24 to 26, and the controller 30 constitute control means, and the lock valve 15 and the electromagnetic control valve 31 constitute work / non-work detection means.

[0041]

As described in detail above, claim 1
According to the third aspect, the vehicle height can be adjusted by allowing the hydraulic cylinder to expand and contract when the vehicle is not running, and the vehicle height can be adjusted by inhibiting the expansion and contraction of the hydraulic cylinder due to the supply of external pressure oil when the vehicle is running. As a result, there is no need to consider the height adjustment function for the design related to the suspension performance during driving,
The setting of each part relating to the suspension performance becomes easy.
According to the second and fourth aspects of the present invention, the vehicle height can be adjusted by allowing the hydraulic cylinder to expand and contract during non-operation, and the vehicle height can be adjusted by preventing the expansion and contraction of the hydraulic cylinder during operation. When working, there is no inflow of pressure oil due to vehicle height adjustment,
You can work without feeling uncomfortable while feeling the excavation reaction force.

[Brief description of the drawings]

FIG. 1 is a side view of a wheel shovel equipped with a vehicle height adjusting device according to an embodiment of the present invention.

FIG. 2 is a front view of a wheel shovel equipped with the vehicle height adjusting device according to the embodiment of the present invention (A view in FIG. 1).

FIG. 3 is a view of the wheel shovel equipped with the vehicle height adjusting device according to the embodiment of the present invention as viewed from the bottom (a view B in FIG. 1).

FIG. 4 is a hydraulic circuit diagram showing a configuration of a vehicle height adjusting device of the wheel shovel according to the first embodiment of the present invention.

FIG. 5 is a sectional view of a directional control valve included in the vehicle height adjusting device of the wheel shovel according to the first embodiment of the present invention.

FIG. 6 is an electric circuit diagram of the vehicle height adjusting device of the wheel shovel according to the first embodiment of the present invention.

FIG. 7 is a diagram showing an expanded and contracted state of a cylinder constituting the vehicle height adjusting device of the wheel shovel according to the embodiment of the present invention.

FIG. 8 is a hydraulic circuit diagram showing a configuration of a vehicle height adjusting device of a wheel shovel according to a second embodiment of the present invention.

FIG. 9 is a flowchart illustrating an example of a process performed by a controller included in the vehicle height adjusting device of the wheel shovel according to the second embodiment of the present invention.

[Explanation of symbols]

 1, 1 'Axle 2 Hydraulic cylinder 5a, 5b, 6a Restrictor 7 Accumulator 8 Directional switching valve 12 Hydraulic pilot switching valve 14, 18 Electromagnetic switching valve 15 Lock valve 17 Pilot check valve 21 Brake switch 22 Vehicle height adjustment switch 24 to 26 Relay Reference Signs List 30 controller 31 electromagnetic control valve 85 cab 86 gate lock lever 86a gate lock switch 87 chassis frame

Continued on the front page (72) Inventor: Toshihiro Tateno 650, Kandachi-cho, Tsuchiura-shi, Ibaraki F-term in the Tsuchiura Plant of Hitachi Construction Machinery Co., Ltd. (Reference) 3D001 AA10 AA13 BA54 CA08 DA17 EA05 EA07 EA22 EB08 ED02

Claims (4)

[Claims] A hydraulic cylinder connected to at least one of the left and right axles provided on the front and rear of the vehicle and the vehicle body, and an accumulator communicated with each of oil chambers of the hydraulic cylinder via a throttle. In a wheel shovel equipped with a suspension, a cylinder expanding / contracting means for supplying hydraulic oil to each of the hydraulic cylinders, discharging hydraulic oil from each of the hydraulic cylinders, and expanding and contracting each of the hydraulic cylinders, and a running / non-running state of the vehicle When a non-traveling state is detected by the traveling detecting means, expansion and contraction of each of the hydraulic cylinders by the cylinder extending / contracting means is allowed, and when the traveling state is detected by the traveling detecting means, Inhibiting expansion and contraction of each of the hydraulic cylinders by the cylinder expansion and contraction means to exert a suspension function A vehicle height adjusting device for a wheel shovel, comprising: a control unit. And a work detecting means for detecting a working / non-working state of the vehicle, wherein the control means, when a non-working state is detected by the work detecting means, the respective ones of the cylinder expanding / contracting means. Allows the hydraulic cylinder to expand and contract,
2. The vehicle height adjustment of a wheel shovel according to claim 1, wherein when the work state is detected by the work detection unit, the suspension function is locked by inhibiting expansion and contraction of each of the hydraulic cylinders by the cylinder expansion and contraction unit. apparatus. 3. The vehicle height adjusting device for a wheel shovel according to claim 1, wherein the traveling detecting means detects a traveling / non-traveling state based on a vehicle speed or a braking state. 4. A gate lock lever operated to a release position for preventing the occupant from getting on and off the vehicle in a route where the occupant gets on and off the driver's cab; Sometimes allow work,
Work / non-work control means for inhibiting work when in the lock position, wherein the work detection means detects work when the gate lock lever is in the release position, and detects non-work when the gate lock lever is in the lock position. The vehicle height adjusting device for a wheel shovel according to claim 2, wherein