JP2000233620A - Suspension for wheel shovel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly vertically move and swivel an axle relative to a frame, while absorbing a shock from the axle. SOLUTION: A pair of brackets 3 is mounted to be separated to the front/ rear on right/left side surfaces of a frame 87. A protrusion part 2t is provided before/behind a cylinder tube of a hydraulic cylinder 2, and this protrusion part 2t is turnably inserted to an opening part 3a of the bracket 3. One side (left side) of the frame 87, one end of a link 4, and the center of an axle 1, the other end of the link 4, are turnably connected respectively through pins 93, 94. The frame 87 and the axle 1 are thus connected by the right/left hydraulic cylinders 2, so as to absorb a shock of vertical movement and swiveling from the axle 1, and by connecting the frame 87 and the axle 1 by the link 4, movement of the axle 1 relative to the frame 87 is smoothed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, work vehicles moving with wheels such as wheel shovels have tended to run at high speeds, and it is necessary to further improve the ride comfort of operators during high speed running. Therefore, for example, Japanese Patent Application Laid-Open No. 62-110509
And Japanese Patent Application Laid-Open No. 7-132723 disclose a device in which a suspension mechanism is provided between a vehicle body and an axle.

According to the apparatus described in Japanese Patent Application Laid-Open No. 62-110509, two sets of hydraulic cylinders are provided on the left and right sides of the vehicle body, and the upper end of the vehicle body and the cylinder tube, and the lower end of the beam and cylinder rod installed on the axle. And a long hole in the vertical direction is provided at the center of the vehicle body, and the upper center of the beam and the center of the vehicle body are connected by a pin inserted into the long hole. Then, the bottom chambers of the left and right hydraulic cylinders communicate with each other via a throttle, and are connected to an accumulator via a pressure regulating valve, and a pipe between the pressure regulating valve and the accumulator allows a flow to the accumulator side. Connect to hydraulic pump via valve. As a result, when the wheels receive a large impact during traveling, the vehicle body moves up and down due to the contraction of the hydraulic cylinder, but the load is attenuated because the pressure regulating valve is opened and the hydraulic cylinder is connected to the accumulator. When one of the right and left wheels receives an impact, the pressure oil from one hydraulic cylinder flows into the other hydraulic cylinder, and the vehicle body swings.

According to the device described in JP-A-7-132723, the center of the vehicle body and the upper end of a cylinder tube of a set of hydraulic cylinders, and the center of the axle and the lower end of a cylinder rod are respectively pin-coupled to each other. The center of the vehicle and either the left or right of the vehicle body are connected by a link.
Then, the bottom chamber of the hydraulic cylinder is connected to the accumulator via the throttle. As a result, when the wheels receive a large impact during traveling, the vehicle body moves up and down due to the contraction of the hydraulic cylinder, but the load is attenuated because the hydraulic cylinder is connected to the accumulator.

[0005]

However, the apparatus described in Japanese Patent Application Laid-Open No. 62-110509 has the following problems. In other words, since the vehicle body and the axle are connected by pins, when a load in the front-rear direction acts on the vehicle body and the axle during excavation work or during braking during traveling, etc., the load is applied by the pins. Therefore, it is necessary to use a large pin having a large pin diameter in consideration of the strength of the pin. In addition, since the movement of the axle with respect to the vehicle body is restricted by the pin, the pin slides up and down as the axle moves up and down, and the abrasion of the sliding portion is promoted. as a result,
The play between the pin and the long hole becomes large, and the displacement of the axle with respect to the vehicle body is added not only in the up-down direction but also in the left-right direction, making it difficult to smoothly absorb shock. Furthermore, since the hydraulic cylinder used is a single-acting type only on the contraction side,
Since the shock cannot be hydraulically absorbed at the time of extension, the shock acts on the structural member.

In the device described in Japanese Patent Application Laid-Open No. Hei 7-132723, since the vehicle body and the axle are connected by the central hydraulic cylinder and the link, there is no limitation on the vibration of the vehicle body. Can not absorb shocks to As described above, the apparatus described in the above publication cannot smoothly move the frame up and down and swing while absorbing the impact from the axle, which is not practical.

An object of the present invention is to solve the above-mentioned problems and to provide a practical wheel shovel suspension.

[0008]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIGS. (1) The invention according to claim 1 is a hydraulic cylinder 2 connected to at least one of an axle 1 provided at the front and rear of the vehicle and a vehicle body 87, and oil chambers 2b, 2 of the hydraulic cylinder.
The present invention is applied to a suspension of a wheel shovel which has an accumulator 7 which communicates with the cylinder c through throttles 5a, 5b, 6a, and at least makes the hydraulic cylinder 2 and the accumulator 7 exhibit a suspension function at the time of traveling. The above-described object is achieved by disposing the hydraulic cylinders 2 on the left and right sides of the vehicle body 87 and connecting the vehicle body 87 and the axle 1 by the link 4 to suppress the amount of displacement of the vehicle body 87 in the left-right direction. . (2) According to the second aspect of the invention, at least the mounting tolerance of the link 4 to the vehicle body 87 and the axle 1 in the vehicle longitudinal direction is made smaller than the mounting tolerance of the hydraulic cylinder 2 to the vehicle body 87 and the axle 1 in the vehicle longitudinal direction. . (3) The invention of claim 3 is that the hydraulic cylinder 2 is connected to the vehicle body 87 via a pair of mounting members 3 that rotatably sandwich the side surface of the cylinder tube from the vehicle front-rear direction. (4) According to the invention of claim 4, the cylinder tube has projections 2t on the front and rear side surfaces of the vehicle, and each projection 2t is rotatably inserted into the opening 3a of the mounting member 3. (5) According to the fifth aspect of the present invention, the mounting members 3 are positioned and mounted on the vehicle body 87 via the knock pins 52, respectively. (6) The invention of claim 6 connects the hydraulic cylinder 2 to the vehicle body 87 and the axle 1 such that each of the longitudinal axes 2L of the pair of hydraulic cylinders 2 faces outward in the vehicle width direction of the axle 1. . (7) In the invention of claim 7, the link 4 comprises a plurality of plate members 4a to 4f, and these plate members 4a to 4f form a box-shaped closed space.

In the meantime, in the section of the means for solving the above-mentioned problem which explains the constitution of the present invention, the drawings of the embodiments of the present invention are used in order to make the present invention easy to understand. However, the present invention is not limited to this.

[0010]

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 87 (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 '.
Note that the frame 87 has a bucket holder 87a at the forefront. 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 (view A in FIG. 1) of the wheel shovel to which the present invention is applied, FIG. 3 is a view A in FIG. 2 (view from the side), and FIG. FIG. 3 is a diagram viewed from the arrow B in FIG. 2 (view from the bottom). 2 to 4 show the state when the vehicle body is stopped (initial state). In these figures, the frame 87 and the axle 1 are shown by two-dot chain lines. As shown in FIGS. 2 and 3, a pair of brackets 3 spaced apart in the front and rear direction are provided on the left and right side surfaces of the frame 87.
1, respectively. A circular opening 3a is provided at the upper part of each bracket 3. The front and rear protrusions 2t provided on the upper side surface of the cylinder tube of the hydraulic cylinder 2 are inserted into the opening 3a, whereby the cylinder tube is rotatably supported. The mounting position of each bracket 3 with respect to the frame 87 is determined by the knock pin 52, thereby preventing the protrusion 2 t of the hydraulic cylinder 2 from hitting the opening 3 a of the bracket 3. Note that a method in which the hydraulic cylinder 2 is sandwiched between the pair of brackets 3 is called a trunnion type. The tip of the piston rod 2a is pin 9
It is pivotally connected to the axle 1 via 2. In this case, in the initial state, the axis 2L of the pair of left and right hydraulic cylinders 2 has a C shape, that is, the piston rod 2a.
The hydraulic cylinder 2 is mounted such that the tip of the hydraulic cylinder 2 faces outward in the vehicle width direction.

As shown in FIGS. 2 and 4, one of the left and right ends (left side in the figure) of the frame 87 and the center of the axle 1 (on the center line 1L) are connected by a link 4. The link 4 includes a main plate 4a spaced apart in front and rear, a reinforcing plate 4b welded to the outer surface of the main plate 4a on the axle side, and three side plates welded at both ends to the inner surface of the main plate 4a. 4c-4e, and a pipe 4f welded to the end face of the main plate 4a on the body frame 87 side, and the side plates 4c-4e
And the pipe 4f form a box-shaped closed space. A front plate 87b and a rear plate 87b are provided on the frame 87 so as to be separated from each other by the axial length of the pipe 4f, and the front and rear plates 87b and 4f are pin-inserted by inserting the pipe 4f and passing the pins 93 therebetween. It is connected rotatably via 93. On the other hand, an attachment member 1a for the link 4 is provided on the axle 1, and a main plate 4a is arranged so as to sandwich the attachment member 1a. Mounting member 1a and main plate 4a
Are rotatably connected via a pin 94.

By pin-connecting the frame 87 to the link 4 and the axle 1 to the link 4 in this manner,
As shown in FIG. 2, the link 4 rotates as indicated by an arrow with the pin 93 as a fulcrum, and the axle 1 mainly moves up and down with respect to the frame 87 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. In this case, the axial length of the pipe 4f and the pair of front plates 87 of the frame 87
b, a fitting tolerance between the interval between the rear plates 87b (gap at the fitting portion L1 in FIG. 4), and a fitting tolerance between the interval between the pair of main plates 4a and the axial length of the mounting member 1a of the axle 1 (see FIG. 4 so that the clearance at the fitting portion L2 of the hydraulic cylinder 2 is smaller than the play of the mounting portion of the hydraulic cylinder 2.
Set the mounting tolerances as tight as possible. Thus, the load in the front-rear direction of the vehicle body from the frame 87 is transmitted to the axle 1 via the link 4 instead of the hydraulic cylinder 2.

FIG. 5 is a hydraulic circuit diagram showing the configuration of the suspension according to the present embodiment. The suspension according to the present embodiment has a vehicle height adjustment function and a suspension lock function in addition to a suspension function during traveling. As shown in FIG. 5, the accumulator 7 is connected to a main hydraulic power source 13 via a direction switching valve 8, a center joint 11, and a hydraulic pilot switching valve 12. The position of the direction switching valve is switched by manual operation of a switching lever provided below the frame. A pilot port 12 a of the hydraulic pilot switching valve 12 is connected to a pilot hydraulic source 16 via an electromagnetic switching valve 14 and a lock valve 15. The position of the lock valve 15 is switched by the operation of a gate lock lever 86 provided in the driver's cab 85, and the position is switched to the position (A) when the gate lock lever 86 is operated to the release position, and to the position when the gate lock lever 86 is operated to the lock position. (B). Solenoid switching valve 1
4 is a solenoid 14 according to an electric signal I described later.
When a 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.

A throttle 6a having an area A1 is provided in a pipe 6 connected to the accumulator 7, and a throttle 5a having an area A2 is provided in a pipe 5 which communicates the pair of cylinder blocks 3, respectively. 6a has at least A1
> A2 holds. Therefore, cylinder 2
When the high-pressure oil is supplied into the pipe line 5 by contraction, the pressure oil is accumulated in the accumulator 7 through the throttles 5a and 6a, and the accumulated pressure oil is returned to the neutral position so that the vehicle body returns to the neutral position. Is supplied to the cylinder 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 bifurcated 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 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, 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, the pilot check valve 17 is opened by turning on the vehicle height adjustment switch 22 in the parking mode, and the vehicle height can be adjusted by operating the direction switching valve 8 if other vehicle height adjustment conditions are satisfied. Becomes Further, when the brake switch 21
When the contact is switched to the 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. As a result, the pilot check valve 17 is opened during traveling,
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. 5, 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, the rod chamber 2c, and the accumulator 7 of each cylinder 2 is enabled, and the suspension function is exhibited. In the traveling mode, the direction switching valve 8 is switched to the neutral position, and the switching lever 8a is provided at the lower portion of the frame 87, so that the switching lever 8a is not operated during traveling and the direction is switched. The outflow of pressure oil from the valve 8 is prevented. That is, the vehicle height does not decrease during traveling due to an erroneous operation.

In such a running mode, for example, when the work vehicle is running at a high speed, a high cycle vibration is generated through 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.

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 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).

Here, the frame 87 for the axle 1
An example of the displacement will be described. In the initial state, as shown in FIG. 2, the contraction amount of the hydraulic cylinder 2 is set so that the center line 87L of the frame 87 and the center line 1L of the axle 1 match. When the left and right wheels are simultaneously impacted and the hydraulic cylinder 2 contracts, the link 4 rotates about the pin 93 as a fulcrum and the center line 8 of the frame 87 as shown in FIG.
7L is shifted leftward from the center line 1L of the axle 1. Conversely, when the hydraulic cylinder 2 is extended, the center line 87L of the frame 87 is shifted to the right from the center line 1L of the axle 1, as shown in FIG. When the center line 87L of the frame 87 and the center line 1L of the axle 1 are displaced in this way, the side surface of the frame 87 and the hydraulic cylinder 2 approach each other.
As shown in the figure, the hydraulic cylinder 2 initially has its axis 2
Since L is attached so as to have a C shape,
Interference between the side surface of the frame 87 and the hydraulic cylinder 2 is prevented.

(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. 5, 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. FIG.
In the parking mode, the brake switch 21 is switched to the P contact 21P side as shown in FIG.
The coils 25c and 26c of 5, 26 are not energized and the relay 2
5 and 26 are switched to the a contacts 25a and 26a, respectively. Here, when the vehicle height adjustment switch 22 is turned on (closed) to perform the vehicle height adjustment, the solenoid 14a of the electromagnetic switching valve 14 is excited, and the coil 2 of the relay 24 is energized.
4c is energized, the relay 24 is switched to the b contact 24b side, and the solenoid 18a of the electromagnetic switching valve 18 is excited.

As shown in FIG. 5, 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 extended, the switching lever 8a is operated 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. When the cylinder 2 is to be contracted, the switching lever 8a is operated to switch the direction switching valve 8 to the position (C). Then, each cylinder 2
The pressure oil from the oil chambers 2b 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. The vehicle height is adjusted in this manner, and when the vehicle height reaches a predetermined value, 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 an 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. Further, since the mounting tolerance in the front-rear direction (gap in the front-rear direction) of the link 4 is set smaller than the mounting tolerance in the front-rear direction (play in the front-rear direction) of the hydraulic cylinder 2, the load in the front-rear direction from the attachment 84 is applied to the link 4. The load is transmitted, and the load in the front-rear direction does not act on the hydraulic cylinder 2. As a result, the hydraulic cylinder 2 is protected.
In this case, the link 4 has a box shape, and the main plate 4
Since the reinforcing plate 4b is provided on the outside of "a", the bending rigidity and torsional rigidity of the link 4 are increased, and the link 4 can sufficiently withstand the excavation load.

As described above, according to the present embodiment, the frame 87 and the axle 1 are connected by the pair of left and right hydraulic cylinders 2 and one link 4, so that the
, The axle 1 can smoothly move up and down and swing with respect to the frame 87. Also,
The rod chamber 2c and the bottom chamber 2b of the hydraulic cylinder 2 are throttled 5
Since it communicates with the accumulator 7 via a, 5b and 6a, it is possible to effectively absorb the shock when the hydraulic cylinder 2 expands and contracts.

Further, since the hydraulic cylinder 2 is supported by a trunnion type, the total length of the cylinder tube (TL in FIG. 3) can be shortened. An extra space can be secured. In addition, since the projection 2t is provided on the cylinder tube and the hydraulic cylinder 2 and the bracket 3 are connected via the projection 2t, for example, as shown in FIG. 8, a pin 53 is inserted into the projection 2t of the cylinder tube, and Compared with the type in which the hydraulic cylinder 2 and the bracket 3 are connected via the pin 53, the width WL in the front-rear direction can be reduced (WL <WL '). Further, since the bracket 3 is positioned by the knock pin 52, the protrusion 2 of the cylinder 2 at the opening 3a of the bracket 3 is formed.
It is possible to prevent one-sided contact of t. Furthermore, since the axis 2L of the hydraulic cylinder 2 is shaped like a letter C, interference between the cylinder 2 and the frame 87 when the cylinder 2 expands and contracts can be prevented.

In the correspondence between the above embodiment and the claims, the bracket 3 constitutes a mounting member.

[0037]

As described above in detail, the present invention has the following effects. (1) According to the first aspect of the present invention, the hydraulic cylinders are arranged on the left and right sides of the vehicle body to connect the vehicle body and the axle, and the vehicle body and the axle are connected by the link. The axle can smoothly move up and down and swing with respect to the vehicle body. (2) According to the second aspect of the present invention, at least the mounting tolerance of the link in the vehicle longitudinal direction is made smaller than the mounting tolerance of the hydraulic cylinder in the vehicle longitudinal direction, so that the load in the vehicle longitudinal direction, for example, an excavation load, acts on the link. And the hydraulic cylinder is protected. (3) According to the third aspect of the present invention, since the side surface of the cylinder tube of the hydraulic cylinder is rotatably held via the mounting member, the overall length of the cylinder tube can be shortened, and the cylinder tube and the revolving body can be connected to each other. A surplus space as a luggage storage space can be secured between them. (4) According to the invention of claim 4, the projection is provided on the side surface of the cylinder tube, and the projection is rotatably inserted into the opening of the mounting member, so that the width between the mounting members in the vehicle longitudinal direction is reduced. Can be shorter. (5) According to the fifth aspect of the present invention, since the mounting member is positioned and mounted on the vehicle body via the knock pin, the pair of mounting members is accurately arranged, and the one end of the connecting portion with the hydraulic cylinder is provided. Can be prevented. (6) According to the invention of claim 6, since the hydraulic cylinder is installed such that the longitudinal axis of the hydraulic cylinder faces outward in the vehicle width direction of the axle, interference between the hydraulic cylinder and the vehicle body when the hydraulic cylinder expands and contracts. Can be prevented. (7) According to the seventh aspect of the present invention, since the link has a box shape, the bending rigidity and the torsional rigidity of the link are increased, and the link can sufficiently withstand an excavation load.

[Brief description of the drawings]

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

FIG. 2 is a front view of a wheel shovel equipped with the suspension according to the embodiment of the present invention (view A in FIG. 1);
Figure).

FIG. 3 is a side view of the suspension according to the embodiment of the present invention (a diagram viewed from an arrow A in FIG. 2);

FIG. 4 is a view of the suspension according to the embodiment of the present invention as viewed from the bottom (view B in FIG. 2).

FIG. 5 is a hydraulic circuit diagram showing a configuration of a suspension according to the embodiment of the present invention.

FIG. 6 is an electric circuit diagram of the suspension according to the embodiment of the present invention.

FIG. 7 is a view showing an example of the operation of the suspension according to the embodiment of the present invention.

FIG. 8 is a side view showing another example of the suspension according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 axle 2 hydraulic cylinder 2b bottom chamber 2c rod chamber 2L axis 2t projection 3 bracket 3a opening 4 link 4a main plate 4b reinforcing plate 4c-4e side plate 4f pipe 5a, 5b, 6a aperture 7 accumulator 87 chassis frame

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Toshihiro Tateno 650, Kandachicho, Tsuchiura-shi, Ibaraki F-term in the Tsuchiura Plant of Hitachi Construction Machinery Co., Ltd. (Reference) 3D001 AA10 AA13 AA17 BA06 CA08 DA02 DA15 EA05 EA34 EB08 EB22 EB24 EB26

Claims (7)

[Claims] 1. A hydraulic cylinder connected to at least one of an axle provided in front of and behind a vehicle and a vehicle body, respectively.
A suspension of a wheel shovel having an accumulator communicated with an oil chamber of the hydraulic cylinder via a throttle, so that the hydraulic cylinder and the accumulator exert a suspension function at least during traveling. A suspension for a wheel shovel, wherein the suspension is disposed on the left and right sides of the vehicle, and the vehicle body and the axle are connected by a link to suppress the amount of lateral displacement of the vehicle body. 2. A mounting tolerance of the link to at least the vehicle body and the axle in a vehicle longitudinal direction,
The suspension of the wheel shovel according to claim 1, wherein a mounting tolerance of the hydraulic cylinder to the vehicle body and the axle in a longitudinal direction of the vehicle is made smaller. 3. The hydraulic cylinder according to claim 1, wherein the hydraulic cylinder is connected to the vehicle body via a pair of mounting members that rotatably sandwich a side surface of a cylinder tube from a vehicle front-rear direction. Wheel excavator suspension. 4. The cylinder tube according to claim 3, wherein the cylinder tube has projections on front and rear side surfaces of the vehicle, and each projection is rotatably inserted into an opening of the mounting member. Wheel shovel suspension. 5. The suspension of a wheel shovel according to claim 3, wherein the mounting members are respectively positioned and mounted on the vehicle body via knock pins. 6. The hydraulic cylinder is connected to the vehicle body and the axle such that each longitudinal axis of the pair of hydraulic cylinders faces outward in the vehicle width direction of the axle. 6. The suspension of the wheel shovel according to any one of items 5 to 5. 7. The link comprises a plurality of plate members,
The suspension of a wheel shovel according to any one of claims 1 to 6, wherein these plate-shaped members form a box-shaped closed space.