JP2000238520A - Wheel type shovel loader having height adjustment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispose an operating lever of a control valve for height adjustment at the most appropriate position. SOLUTION: A control valve 8 for height adjustment is disposed between a conduit connecting a hydraulic cylinder 2 and an accumulator, and a hydraulic pump. The hydraulic cylinder 2 is extended and contracted by switching the control valve 8, and the height of a vehicle body frame 70 is thus adjusted. An operating lever 8a of the control valve 8 is provided projected from a side 71 of the frame forwarder with respect to a front axle. The area in front of as well as over the operating lever 8a is covered by a fender 61F. As a result, the operating lever 8a can be operated while watching the expansion and contraction of the hydraulic cylinder 2, and the operating lever 8a is protected from flying objects.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wheel shovel having a vehicle height adjusting device.

[0002]

2. Description of the Related Art In recent years, work vehicles moving with wheels such as wheel shovels have tended to travel at high speeds. In order to further improve the ride comfort of an operator during high-speed travel, see, for example, Japanese Patent Application Laid-Open No. 6-278438. The publication discloses a work vehicle provided with a suspension mechanism between a vehicle body and an axle. In this work vehicle, return-type hydraulic cylinders are mounted on the left and right side surfaces of the vehicle body, the bottom chambers are connected to each other via piping, and a throttle and an accumulator are provided in the middle of the piping, and each cylinder rod of the hydraulic cylinder is provided. Are each pinned to the axle. With such a suspension mechanism, vibration of the axle during traveling is absorbed and attenuated, and riding comfort during traveling is improved.

[0003] Further, the work vehicle described in the above-mentioned publications includes:
An electromagnetic control valve for adjusting the vehicle height, which is switched by a signal from a control device described later, is provided. By switching the electromagnetic control valve, the hydraulic cylinder can be expanded and contracted to adjust the vehicle height. The control device calculates a difference between a detected value of the distance between the vehicle body and the axle detected by the distance detector and a predetermined set value, and outputs a control signal to the electromagnetic control valve according to the difference. Is output.

[0004]

However, in the work vehicle described in the above publication, the vehicle height is automatically adjusted by a signal from the control device, so that the configuration becomes complicated and the cost increases. Further, since the vehicle height adjustment is not performed while visually observing the distance between the vehicle body and the axle, the vehicle height may be erroneously adjusted, for example, when the distance detector breaks down. Therefore, it is desirable to perform the vehicle height adjustment by operating from outside the cabin while visually observing the distance between the vehicle body and the axle.

However, when an operation lever for a vehicle height adjustment control valve is provided outside the vehicle compartment, not only is the operability difficult, but also the operation lever may be damaged by a flying object from the front. Also, when the suspension circuit is formed by switching the control valve for vehicle height adjustment to the neutral position, the distance from the control valve to the accumulator affects the suspension performance, so that the suspension performance (particularly the performance of the accumulator) is sufficiently exhibited. For this purpose, it is necessary to consider the positional relationship between the control valve and the accumulator.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wheel shovel having a vehicle height adjusting device capable of arranging an operation lever of a vehicle height adjusting control valve at an optimum position.

[0007]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIGS. (1) The invention according to claim 1 provides a hydraulic power source 13 for generating pressure oil.
A hydraulic cylinder 2 provided between the axle 1 of the traveling body 81 and the vehicle body frame 70 to adjust the height of the vehicle body frame 70 by supplying and discharging pressurized oil, and a hydraulic cylinder 2 for adjusting the vehicle height by operating the operation lever 8a. This is a wheel shovel having a vehicle height adjusting device including a vehicle height adjusting valve 8 for switching a supply / discharge path of oil to and from the cylinder 2 and an accumulator 7 connected to the hydraulic cylinder 2 and functioning the hydraulic cylinder 2 as a suspension. And move the operating lever to axle 1
The above-described object is achieved by providing the protruding portion from the side surface of the body frame 70 in front of the vehicle. (2) According to a second aspect of the present invention, in the wheel shovel having the vehicle height adjusting device according to the first aspect, the front of the operation lever 8a and the upper side of the vehicle are covered by the fender 61F. (3) According to a third aspect of the present invention, in the wheel shovel having the vehicle height adjusting device according to the first or second aspect, a mark 73b serving as an index for adjusting the vehicle height is provided on the body frame 73 facing the front of the vehicle. It is.

[0008] 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 easier to understand. However, the present invention is not limited to this.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 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 swing body 83 that is swingably connected to an upper portion of the lower traveling body 81 via a swing device 82. Boom 84A, arm 84B, bucket 84
C for work front attachment 84 (hereinafter, referred to as C)
A driver's cab 85 is provided at the entrance of the driver's cab 85. The gate is operated at a release position (A position) when an operator gets on the vehicle and at a lock position (B position) when getting off the vehicle. A lock lever 86 is provided. The lower traveling body 81 is provided with a chassis frame 70 (hereinafter, referred to as a frame), a traveling hydraulic motor 88, a transmission 89, a propeller shaft 90, and tires 91. The driving force from the propeller shaft 90 is axle 1, It is transmitted to the tire 91 via 1 '.
Fenders 61F and 61R are provided before and after the frame 70 so as to cover the upper part of the tire 91, and a hydraulic cylinder 2 described later is installed inside the front fender 61F. In the present embodiment, the rear axle 1 '
Is fixed directly to the frame 70, and the front axle 1 is connected to the frame 70 via the following suspension mechanism.

FIG. 2 is a diagram of the wheel shovel to which the present invention is applied, as viewed from the bottom (view A in FIG. 1). FIG. 3 is a diagram of the lower traveling body 81 viewed from the front of the vehicle (front of FIG. 1). FIG. 4 is a sectional view taken along the line IV-IV of FIG. 2 mainly showing the mounting state of the accumulator 7. In FIG. 2, the axle 1 is located immediately below the hydraulic cylinder 2, but is not shown. As shown in FIGS. 2 to 4, the frame 70 includes left and right side plates 71 and 72 arranged on the front side of the vehicle, and a front plate 73 and a rear plate 74 abutting on front and rear end surfaces of the side plates 71 and 72, respectively. Left and right side plates 75 and 76 (which are substantially U-shaped as shown in FIG.
And an upper plate 77 in contact with the upper surface of each of the plates 71-76. The left and right ends of the front plate 73 are the side plates 7
It protrudes more than 1,72 and its protruding part 73a
A fender 61F is attached to the (see FIGS. 2 and 3).

As shown in FIGS. 2 and 3, the front left and right side plates 7 are provided.
A pair of brackets 3 spaced apart from each other are attached to the first and second brackets 72, and a cylinder tube of a hydraulic cylinder 2 that is extendable and contractible is rotatably held between the brackets 3. The tip of the piston rod 2a is a pin 92.
And is rotatably connected to the axle 1 via. One end of the link 4 is rotatably connected to one of the left and right sides (the left side in the figure) of the front plate 73 and the rear plate 74 via a pin 93, and the other end passes through an opening 70 a at the bottom of the frame 70 and is connected to the axle 1. (On the center line CL), and is rotatably connected via a pin 94. As a result, as shown in FIG.
Rotates as indicated by the arrow, and the axle 1 mainly moves up and down with respect to the frame 70 within the range of expansion and contraction of the piston rod 2a. In some cases, the axle 1 swings around the pin 94 as a fulcrum within the range of expansion and contraction of the piston rod 2a.
At the center of the lower part of the front plate 73, as shown in FIG. 3, a notch 73c having a projection 73b on the inside is provided, so that the head of the pin 94 can be seen from the front of the vehicle. A nipple 94a for injecting grease is provided at the center of the head of the pin 94, and the height of the vehicle is adjusted while visually observing the positional relationship (height relationship) between the nipple 94a and the projection 73b of the front plate 73 as described later. Adjusted.

As shown in FIG. 2, the left and right hydraulic cylinders 2
Are connected via a pipe 5 and in the middle of the pipe 5 (center)
Is connected to an accumulator 7 via 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. The direction switching valve 8 is arranged on the opposite side (right side) of the link 4 from the left and right of the vehicle, and the accumulator 7 is arranged right behind the link 4 and at the center in the left and right direction. Details of the hydraulic circuit will be described later with reference to FIG. The hydraulic pump 13 and the tank, which will be described later, are installed on the upper swing body 83 (see FIG. 1).
Hydraulic cylinder 2 in which hydraulic oil from hydraulic pump 13 is set to lower traveling body 81 via center joint 11
Oil is discharged from the hydraulic cylinder 2 to the tank via the direction switching valve 8 and the center joint 11.

The accumulator 7 is of a so-called diaphragm type in which gas and oil inside are separated by a diaphragm. Compared with a so-called bladder type accumulator in which the inside gas and oil are separated by a bladder, the following features are provided. Have. That is, the diaphragm type has a circular shape as a whole, and the height in the longitudinal direction is lower than that of the bladder type. In addition, the diaphragm type has no restrictions on its posture due to its structure, and its longitudinal direction can be arranged in a vertical direction (hereinafter, this is called vertical installation), or its longitudinal direction can be arranged in a horizontal direction (hereinafter, referred to as a vertical arrangement). , This is referred to as horizontal placement). On the other hand, the bladder type is difficult to use in a horizontal position due to its structure. As shown in FIG. 2, in the present embodiment, a diaphragm type accumulator 7 is mounted horizontally.

As shown in FIG. 4, the left and right side plates 75, 76 on the rear side of the frame 70 are formed in a U-shaped cross section.
A horizontally long space is provided between 7 and the side plates 75 and 76. An L-shaped bracket 7 is provided on the lower surface of the upper plate 77.
7a are welded (see FIG. 2), and a leg member 40a integrated with the band 40 is bolted to the bracket 77a.
Has been concluded. The band 40 is formed in a substantially C shape,
An accumulator 7 is attached to the inside.
Bolts 42 are inserted into both ends of the band 40, and nuts 43 are screwed into the bolts 42. When the bolts 42 are tightened, the band 40 contracts, thereby fixing the accumulator 7. The above-mentioned pipe 5 is suspended by left and right side plates 75 and 76 via a pipe fixing member 44.

In the space formed between the left and right side plates 75, 76, the accumulator 7 has an upper end that does not protrude from the upper plate 77 of the frame 70 and a lower end of which is a lower end surface of the side plates 75, 76. It is arranged without projecting from. That is, the entire accumulator 7 is accommodated inside the upper end face and the lower end face of the frame 70. By arranging the accumulator 7 in this way, the accumulator 7 is stored inside the frame 70 and is protected from flying objects and the like, and the appearance is improved. Also, since the accumulator 7 is mounted horizontally,
It is possible to prevent the pipe 6 connected to the accumulator 7 from protruding downward. In this case, the pipe 5 connecting the left and right hydraulic cylinders 2 protrudes downward from the lowermost surfaces of the side plates 75 and 76, and is laterally suspended. However, since there is no protrusion of the pipe 6, the amount of protrusion can be minimized. it can. In this embodiment, the diaphragm type accumulator 7 is used. However, when a bladder type accumulator is mounted instead, the height is increased, and the left and right side plates 75, 7 are increased.
It becomes difficult to store the accumulator in the space formed by the upper plate 6 and the upper plate 77.

Next, the mounting position of the switching lever 8a for switching the direction switching valve 8 will be described. FIG. 5 is FIG.
6 is an enlarged view (partially sectional view) of a part a of FIG. 3, and FIG. 6 is an enlarged view (partially sectional view) of a part b of FIG. As shown in FIGS.
The side plate 71 on the vehicle front side with respect to the hydraulic cylinder 2 is provided with a slot hole 71a in a vertical direction, and the switching lever 8a penetrates the slot hole 71a and protrudes outside the side plate 71. When viewed from the front side of the vehicle, the entire switching lever 8a is hidden by the shadow of the fender 61F, and the upper part of the switching lever 8a is covered with the fender 61F. The switching lever 8a is operable along the slot hole 71a. When the switching lever 8a is operated from the neutral position shown in FIG. 6 to the position A, the direction switching valve 8 is switched as described later to increase the vehicle height. When operated to the position B, the direction switching valve 8 is switched as described later, and the vehicle height is reduced. In this embodiment, a fixed cover 45 that is detachable from the side plate 71 by two butterfly nuts 46 is provided in order to restrict the movement of the switching lever 8a except when adjusting the vehicle height. The fixed cover 45 is formed of a substantially rectangular thin plate so as to cover the slot hole 71a, and a cutout 45a is provided in a part thereof (at a position corresponding to the neutral position of the switching lever 8a). Is restrained.

FIG. 7 is a hydraulic circuit diagram showing the configuration of the suspension according to the embodiment of the present invention. The suspension according to the embodiment has a vehicle height adjusting function and a suspension lock in addition to a suspension function during traveling. Function. As shown in FIG.
Is connected to the main hydraulic power source 13 via the direction switching valve 8 and the center joint 11 described above, and further via the hydraulic pilot switching valve 12. Hydraulic pilot switching valve 12
The pilot port 12a 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, it is switched to the position (a), and when it is operated to the lock position, it is switched to the position (b). The solenoid-operated directional control valve 14 is controlled by an electric signal I to be described later.
When the solenoid 4a is excited, the position is switched to the position (b), and when the solenoid 14a is demagnetized, the position is switched to the position (a).

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 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). As a result, the pressure oil from the main hydraulic pressure source 13 is supplied to the directional control valve 8, and adjustment to increase the vehicle height becomes possible. When at least one of the lock valve 15 and the electromagnetic switching valve 14 is switched to the position (A), the hydraulic pilot switching valve 12
The pilot port 12a is communicated with the tank, and the hydraulic pilot switching valve 12 is switched to the position (a). As a result, the directional control valve 8 is communicated with the tank, and the adjustment to increase the vehicle height is prohibited, and the adjustment to decrease the vehicle height becomes possible.

The direction switching valve 8 is a three-port three-position switching valve, and is constituted by, for example, a ball valve as shown in FIG. When the switching lever 8a is operated toward the position A in FIG.
The direction switching valve 8 is switched to the position (A), and the A port 8
A communicates with the P port 8P. When the switching lever 8a is operated toward the position B in FIG. 6, the direction switching valve 8 is switched to the position (C), and the A port 8A communicates with the T port 8T. When the switching lever 8a is further operated to the neutral position, the direction switching valve 8 is switched to the position (b), and the A port 8A is switched to the P port 8P and the T port 8T as shown in FIG.
, That is, the leakage amount from the A port 8A becomes almost zero.

The directional control valve 8 has a body 8b provided with a P port (pump port) 8P, a T port (tank port) 8T and an A port (service port) 8A.
And a ball 8c that is built into the body 8b and that can be switched to the above-mentioned position (a), (b) and (c) by an external operation. Therefore, the direction switching valve 8 has both a function as a direction switching valve for switching the flow of the pressure oil and a function as a stop valve for shutting off the flow of the pressure oil and having a substantially zero leakage amount. And
When the ball 8c is operated between the position (a) and the position (b), the opening area becomes in accordance with the operation amount of the ball 8c, and a stop valve having a so-called metering property can be obtained. .

As shown in FIG. 7, 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 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), pressure oil from the pilot hydraulic 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. 9 is an electric circuit diagram of the suspension according to the present embodiment. As shown in FIG. 9, 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. 9 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, the solenoid 28 for operating the work brake is excited to operate the work brake, and the solenoid 27 for releasing the parking brake is demagnetized to operate the parking brake. When the brake switch 21 is switched to the P contact 21P side, the solenoid 2 for releasing the parking brake is released.
7 is demagnetized and the parking brake operates. The work brake and the parking brake are well-known, and their illustration is omitted.

The solenoid 18a of the electromagnetic switching valve 18 has 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. That is, by turning on the vehicle height adjustment switch 22 in the parking mode, the pilot check valve 17 is released, and if other vehicle height adjustment conditions are satisfied, the vehicle height can be adjusted by operating the switching lever 8a. Become. 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 solenoid 18a of the electromagnetic switching valve 18 is connected to the power supply 23 and is excited. Thereby, the pilot check valve 17 is opened during traveling, and the hydraulic cylinder 2 can be used as a suspension.

Next, the operation of the suspension according to the present 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 shown in FIG. 7, 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, and the suspension function is exhibited.

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 70, and even when the tire 91 receives an external force from the road surface during traveling, the external force Is prevented from being transmitted directly to the frame 70. 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 unevenness of the road surface when the work vehicle is running at a 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 side 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 (open), the solenoid 14a of the electromagnetic switching valve 14 is demagnetized,
The circuit to the coil 24c of the relay 24 is disconnected, and the relay 24 is switched to the a contact 24a side.
Is demagnetized.

As shown in FIG. 7, 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. That is, even if the switching lever 8a is operated when the vehicle height adjustment switch 22 is off,
Supply and discharge of pressure oil to and from the hydraulic cylinder 2 are prohibited, and the vehicle height does not undesirably fluctuate.

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 attached, and as shown in FIG. 10A, positions where the strokes L1 and L2 of the cylinder 2 in the contraction direction and the extension direction are equal (L1 = L2). And the piston 2p is stationary. Here, as shown in FIG. 10B, when the attachment 84 'is replaced with an attachment 84' having a weight W '(> W), the cylinder 2 contracts, the front vehicle height decreases, and the stroke possible amount L1' in the contracting direction. Becomes smaller (L1 '<L1). Further, as shown in FIG. 10C, 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 possible stroke 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 amount L1 ″,
L2 '' becomes small and the suspension function cannot be fully exhibited, and the ride quality deteriorates. 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 ″). In the present embodiment, in this proper vehicle height state, the frame 7
The height of the projection 73b provided on the front plate 73 of the No. 0 is equal to the height of the nipple 94a provided on the head of the pin 94 of the axle 1.

As shown in FIG. 9, in the parking mode, since the brake switch 21 is switched to the P contact 21P side, 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 25a. 26a
Side. Here, when the vehicle height adjustment switch 22 is turned on (closed) to perform vehicle height adjustment, the solenoid 14a of the electromagnetic switching valve 14 is excited, the coil 24c of the relay 24 is energized, and the relay 24 is closed. 2
4b, the solenoid 1 of the electromagnetic switching valve 18
8a is excited.

As shown in FIG. 7, 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, the cylinder 2 is shown in FIG.
(L1 ′ <2 ′), that is, the height of the projection 73b provided on the front plate 73 of the frame 70 is lower than the height of the nipple 94a provided at the tip of the pin 94 of the axle 1, Cylinder 2 to make L1 '= L2'
Is extended, a hand is inserted between the side plate 71 and the tire 91 from the front right of the frame 70, and the butterfly nut 46 is inserted.
And remove the fixing cover 45. Next, the switching lever 8a is operated in the direction of arrow A in FIG. 6 to switch the direction switching valve 8 to the position (a). Then, the pressure oil from the main oil pressure source 13 is supplied via the direction switching valve 8 to the oil chambers 2b,
2c respectively, whereby the piston 2p
The force F (force in the extension direction) acting on the cylinder 2 increases, the cylinder 2 extends, and the vehicle height increases. Also, the cylinder 2 is in the state of FIG. 10C (L1 ″> L2 ″), that is, the height of the projection 73b provided on the front plate 73 of the frame 70 is provided at the tip of the pin 94 of the axle 1. Nipple 94
When the cylinder 2 is contracted to make L1 ″ = L2 ″, the switching lever 8
a is operated to the arrow B side in FIG. 6 to switch the direction switching valve 8 to the position (C). Then, the oil chamber 2 of each cylinder 2
The pressure oil from b and 2c 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 decreases. In this way, the height of the vehicle is raised or lowered,
When the height of 3b becomes equal to the height of the nipple 94a, that is, when L1 '= L2', L1 '' = L2 '', the switching lever 8
By operating a to the neutral position, the direction switching valve 8 is switched to the position (b). Next, the fixed cover 45 is attached so that the switching lever 8a is not operated by mistake.

(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. Therefore, even if the vehicle height adjustment switch 22 is erroneously operated, the vehicle height fluctuation is prohibited.

Further, in this embodiment, further safety is achieved by using the following interlock. If the vehicle height adjustment switch 22 is erroneously turned on, the solenoid 14a of the electromagnetic switching valve 14 is excited, and the electromagnetic switching valve 14 is switched to the position (b). However, in the work mode, the gate lock lever 86 is locked and operated. Therefore, the lock valve 15 is switched to the position (a), so that 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 communicated with the tank. In the work mode, the fixed cover 45 is attached to prevent the switching lever 8a from moving from the neutral position. However, even if the switching lever 8a is operated from the neutral position, the pilot check valve 17 is used as a check valve as described above. By functioning and the P port of the directional control valve 8a communicating with the tank, the oil chamber 2 of each cylinder 2
Movement of pressure oil from b and 2c is reliably prohibited.

In the work mode, the pressure oil from the pilot oil pressure source 16 is supplied to the work pilot valve (not shown) via the lock valve 15, so that the operation lever (not shown) is operated to drive the attachment 84, for example. Then, pilot pressure oil proportional to the operation amount of the operation lever is guided to the pilot-type control valve to operate the control valve, thereby enabling work such as excavation. At this time, since 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 (digging reaction force) due to excavation is not absorbed by the accumulator 7, Work can be performed stably in the suspension locked state.

The effect of the present embodiment configured as described above will be described. (1) Switching lever 8 for driving ball type three-position switching valve 8
a is provided so as to protrude from the side plate 71 of the frame 70 to the side of the vehicle, and the front and upper sides of the switching lever 8a are covered with the fender 61F, so that the switching lever 8a is protected from flying objects and the like. In addition, since the switching lever 8a is disposed in front of the hydraulic cylinder 2 located directly above the axle 1, it is not necessary to put a hand in a deep place, so that operability is improved, and the hydraulic cylinder 2 and the link from the front of the vehicle are improved. 4 can be adjusted while visually observing the change in position, so that the vehicle height can be adjusted easily and reliably. Further, a notch 73 having a protrusion 73 b on the front plate 73 of the frame 70.
c, the projection 73b and the pin 94 are located from the front of the vehicle.
The positional relationship between the axle 1 and the frame 70 can be easily adjusted, and fine adjustment of the vehicle height can be easily performed. Furthermore,
Since there is no need to provide a control device or the like for adjusting the vehicle height, the configuration is simplified and the cost is reduced. Further, since the ball type three-position switching valve 8 is disposed downstream of the center joint 11, that is, provided near the accumulator 7 and the hydraulic cylinder 2, the hydraulic piping between the ball type three-position switching valve 8 and the accumulator 7 is provided. Length (especially pipeline length of pipeline 9)
Can be shortened, and the influence on the suspension performance designed mainly based on the capacity of the accumulator 7 can be reduced. Further, in this embodiment, since the pipe 9 is made of a rubber hose, it is expected that the suspension performance is deteriorated due to elastic deformation at high pressure. Therefore, a rubber hose having a pressure resistance (for example, 350 kg / cm ² ) sufficiently higher than the maximum pressure (for example, 90 kg / cm ² ) of the suspension hydraulic circuit is used to reduce the amount of elastic deformation to suppress the deterioration of suspension performance.

(2) In a hydraulic circuit for controlling the supply and discharge of hydraulic oil to and from the hydraulic cylinder 2 to adjust the vehicle height, the function of a switching valve for switching the supply and exhaust of hydraulic oil and the hydraulic cylinder 2 to the hydraulic pump 13 and the tank The function of a stop valve for shutting off the switching valve 8 is realized by the ball type three-position switching valve 8, and the fixed cover 45 for restricting the switching lever 8a for switching the switching valve 8 to the neutral position is provided. It is held in position (functions as a stop valve), and pressure oil leak from the hydraulic cylinder 2 (leakage) and supply of pressure oil to the hydraulic cylinder 2 are reliably suppressed, so that the vehicle height does not change undesirably. . Further, since the switching valve and the stop valve are integrated, the size can be reduced. Further, since metering (flow control characteristic) according to the operation amount of the ball 8c built in the body 8b is obtained, the movement of the upper swing body 83 during the adjustment of the vehicle height becomes smooth.

(3) Since the diaphragm type accumulator 7 is provided in the middle of the pipe 5 communicating with the cylinder 2, the height is lower than that of the bladder type having the same capacity, and therefore, the left and right side plates 75, 76 are provided. The accumulator 7 can be efficiently arranged (effectively using the space) in the space formed by the upper plate 77 and the upper plate 77. Further, since the accumulator 7 is arranged horizontally, it is not necessary to take out the pipe 6 connected to the accumulator 7 downward, and the height of the accumulator 7 including the pipe 6 can be reduced.

(4) Switching valve 1 that is switched in conjunction with operation of brake switch 21 and gate lock lever 86
2, 14 and 15 are provided, and only when the parking brake is operated and the gate lock lever 86 is operated to the lock position (operation prohibited state), that is, only when the parking mode is selected, pressure is applied to the P port of the directional control valve 8. Supply oil and switch lever 8a
The vehicle height can be adjusted by the operation of the vehicle, so that the vehicle height is not adjusted during traveling and 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.

(5) Brake switch 21 and relay 24
Even if the vehicle height adjustment switch 22 is accidentally turned on during traveling and work,
Alternatively, even if the switching lever 8a is operated at the time of work without attaching the fixed cover 45 (operation is not possible during traveling), the vehicle height adjustment is prohibited (so-called interlock), so that unwanted vehicle height adjustment is prevented. be able to.

In the above-described embodiment, the switching valve function of connecting the vehicle height adjusting and suspension hydraulic cylinder 2 to the hydraulic pump 13 or the tank, and the hydraulic cylinder 2 is disconnected from the hydraulic pump 13 and the tank to prevent leakage. The stop valve function for reducing the number of valves is realized by a single ball type three-position switching valve 8. However, in the case of using a spool type three-position switching valve as disclosed in Japanese Patent Application Laid-Open No. 7-132723, a structure with less leakage is used. May be arranged in series with a spool type three-position switching valve. As the stop valve in this case, a ball-type open / close valve as shown in FIG. 8 or a pilot-type check valve that becomes an open valve or a check valve depending on the pressure acting on the pilot port can be used. In addition, an interlock has been provided to prohibit vehicle height adjustment during traveling or work,
It is not necessary to provide an interlock. Further, in the above embodiment, the predetermined position of the front plate 73 of the frame 70 (the position corresponding to the nipple 94a) to facilitate the adjustment of the vehicle height.
Although the projections 73b are provided on the surface, marks (eg, markings) other than the projections may be provided.

[0046]

As described above in detail, according to the present invention, the operating lever for switching the vehicle height adjusting valve is provided so as to protrude from the side of the body frame in front of the vehicle from the axle. This eliminates the need for hands and improves operability, and allows the position of hydraulic cylinders and links that connect the vehicle body and the axle to be visually observed, so that the vehicle height can be easily and reliably adjusted. According to the second aspect of the present invention, the front of the operation lever and the upper part of the vehicle are covered with the fender, so that the operation lever is protected from flying objects. Further, according to the third aspect of the present invention, since the mark serving as an index at the time of adjusting the vehicle height is provided on the vehicle body frame facing the front of the vehicle, fine adjustment of the vehicle height becomes easy.

[Brief description of the drawings]

FIG. 1 is a side view of a wheel shovel having a suspension according to an embodiment of the present invention.

FIG. 2 is a diagram of a wheel shovel having a suspension according to the embodiment of the present invention, as viewed from a bottom surface (A view in FIG. 1).

FIG. 3 is a front view of a wheel shovel having a suspension according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view (a cross-sectional view taken along line IV-IV in FIG. 2) of the wheel shovel having the suspension according to the embodiment of the present invention.

FIG. 5 is an enlarged view of a main part of the wheel shovel having a suspension according to the embodiment of the present invention (an enlarged view of a part in FIG. 2).

FIG. 6 is an enlarged view of a main part of a wheel shovel having a suspension according to the embodiment of the present invention (an enlarged view of a portion b in FIG. 3).

FIG. 7 is a hydraulic circuit diagram of the suspension according to the embodiment of the present invention.

FIG. 8 is a cross-sectional view of a ball-type three-position directional control valve of the suspension according to the embodiment of the present invention.

FIG. 9 is an electric circuit diagram of a wheel shovel having a suspension according to the embodiment of the present invention.

FIG. 10 is a diagram showing the expansion and contraction state of the cylinder of the suspension according to the embodiment of the present invention.

[Explanation of symbols]

 1: Axle 2: Hydraulic cylinder 7: Accumulator 8: Ball type 3 position switching valve 8a: Operating lever 13: Hydraulic pump 61F: Fender 81: Lower traveling body 70: Chassis frame 73: Front plate 73b: Projection 94: Pin 94a :nipple

 ──────────────────────────────────────────────────続 き Continuing 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. 2D003 AA01 AB01 AC06 BA01 BA02 BB04 DB05 3D001 AA10 AA13 BA54 CA08 DA15 EA05 EB08

Claims (3)

[Claims] An oil pressure source for generating pressure oil, a hydraulic cylinder provided between an axle of a traveling body and a vehicle body frame, and adjusting a height of the vehicle body frame by supply and discharge of pressure oil; A vehicle height adjustment valve including a vehicle height adjustment valve that switches a supply / discharge path of oil to and from the hydraulic cylinder when the vehicle height is adjusted by an operation, and an accumulator that is connected to the hydraulic cylinder and causes the hydraulic cylinder to function as a suspension. A wheel shovel comprising a vehicle height adjusting device, wherein the operation lever is provided so as to protrude from a side surface of the vehicle body frame in front of the axle with respect to the vehicle. 2. The wheel shovel according to claim 1, wherein a front part and a vehicle upper part of the operation lever are covered by a fender. 3. The vehicle excavator having the vehicle height adjusting device according to claim 1, wherein a mark serving as an index for adjusting the vehicle height is provided on the body frame facing the front of the vehicle. Wheel excavator with adjusting device.