JP2007056540A - Excavator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excavator capable of rotationally driving a swivel of the excavator at a high speed, and also rotationally driving the swivel at high torque. <P>SOLUTION: A variable capacity hydraulic motor 21 is interlocked with a rotational operation shaft 11 rotationally operating the swivel. A capacity variable operating section 21b of the variable capacity hydraulic motor 21 is operated by a hydraulic cylinder 41 to constitute a gear operation mechanism 40 so that the variable capacity hydraulic motor 21 can be switched to a small capacity state or a mass capacity state in a switchable manner. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an excavator provided with a swivel.

  Conventionally, the excavator is provided with a constant displacement hydraulic pump Pb and a constant displacement hydraulic motor MT connected to the hydraulic pump Pb, as shown in, for example, Patent Document 1, thereby providing a swivel base 3. The swivel drive was made possible.

JP 2001-355612 A (paragraphs [0031], [0034], FIG. 2)

  In this type of excavator, there is a case where the swivel is swiveled with the bucket of the working device placed on the ground, and the ground is leveled by the bucket that slides on the ground. In this case, a large turning drive load is generated as compared with the case where the work apparatus is swung while the bucket is raised from the ground. Therefore, in a conventional excavator, the bucket is applied too strongly on the ground. In some cases, it was not possible to work efficiently, such as being unable to attach it, or not being able to increase the amount of soil discharged by the bucket too much.

  An object of the present invention is to provide an excavator that can efficiently perform operations such as using a bucket as a dozer means.

In the first invention, in the excavator provided with the swivel,
A variable displacement hydraulic motor for rotating the swivel base is provided, and a shift operation mechanism for performing a capacity changing operation of the variable displacement hydraulic motor is provided.

  In other words, if the speed change mechanism is operated artificially or automatically and the variable displacement hydraulic motor is switched to the large capacity state, the hydraulic motor can be operated even if the performance of the hydraulic pump supplying the hydraulic motor remains unchanged. The swivel base is driven to turn at a higher torque than before the capacity change.

  Therefore, according to the first aspect of the present invention, the swivel base can be driven at high speed by a hydraulic motor switched to a small capacity state or switched normally, and the bucket is used as the dozer means as described above. When the above work is performed, the work can be efficiently performed by rotating the swivel base with a torque higher than usual by the hydraulic motor in a large capacity state and powerfully moving the work device.

  According to the second aspect of the invention, in the configuration of the first aspect of the invention, the speed change operating mechanism is linked to the capacity changing operation unit of the variable capacity hydraulic motor and is configured to switch the variable capacity hydraulic motor to the small capacity state. An energized single-acting hydraulic cylinder, a speed control valve capable of switching between an oil supply state for supplying oil to the hydraulic cylinder and an oil discharge state for discharging oil from the hydraulic cylinder, and the variable displacement hydraulic motor The variable displacement hydraulic motor is driven so that the speed control valve is in an oil supply state when the driving load of the engine is large, and the speed control valve is in an oil discharge state when the drive load of the variable displacement hydraulic motor is small. A control valve switching mechanism for switching the speed control valve in accordance with the load is provided.

  That is, if the drive load of the hydraulic motor is small, the control valve switching mechanism switches the speed control valve to the oil drain state, the speed control valve drains the hydraulic cylinder, and the hydraulic cylinder reduces the hydraulic motor to a small capacity. Switch to the state. When the drive load of the hydraulic motor is large, the control valve switching mechanism switches the speed control valve to the lubrication state, the speed control valve performs the lubrication operation to the hydraulic cylinder, and the hydraulic cylinder switches the hydraulic motor to the large capacity state. To do.

  Therefore, according to the second aspect of the present invention, when the driving load of the hydraulic motor is small, such as when the working device is simply swung, the hydraulic motor is automatically switched to a small capacity state, and the swivel base is driven at high speed. When the load of the hydraulic motor is heavy, such as when the work can be done efficiently and the ground is smoothed by a bucket, the hydraulic motor is automatically switched to a large capacity state and the swivel is driven with high torque And can work efficiently. In addition, the hydraulic motor is automatically switched between the small capacity state and the large capacity state, so that work can be performed easily.

In the third invention, in the configuration of the second invention,
Provide a negative rake that brakes the swivel,
Selecting a high pressure side hydraulic circuit from a pair of hydraulic circuits for driving the variable displacement hydraulic motor, and providing a high pressure selection valve for taking out the hydraulic pressure from the selected high pressure side hydraulic circuit and supplying the hydraulic pressure to the speed control valve;
The control valve switching mechanism is a drain-side pilot oil passage that takes out pilot hydraulic pressure from a brake fluid passage that operates the negative rake and supplies the speed control valve to a drain oil state so as to switch the speed control valve to a drain oil state. An oil supply side pilot oil passage is provided to take out the pilot oil pressure from the valve and supply the speed control valve to the oil supply state so as to switch the speed control valve to the oil supply state.

  That is, the hydraulic pressure extracted by the high pressure selection valve from the hydraulic circuit for driving the hydraulic motor is supplied as a pilot hydraulic pressure to the speed control valve by the oil supply side pilot oil passage, and the oil pressure of the brake operation oil passage is speeded by the oil discharge side pilot oil passage. Supply the control valve as pilot hydraulic pressure, and the pilot hydraulic pressure by the oil supply side pilot oil passage becomes larger than the pilot hydraulic pressure by the oil discharge side pilot oil passage, so that the speed control valve is in the oil supply state, and the pilot oil pressure by the oil supply side pilot oil passage When the oil pressure becomes smaller than the pilot oil pressure in the oil discharge side pilot oil passage, the speed control valve is switched to the oil discharge state. As a result, if the drive load of the hydraulic motor is small, the circuit pressure of the hydraulic circuit becomes small, the pilot pressure in the oil supply side pilot oil passage becomes small, and the speed control valve is switched to the oil-removed state to operate the hydraulic pressure. If the motor is switched to the small capacity state and the drive load of the hydraulic motor is large, the circuit pressure of the hydraulic circuit increases, the pilot pressure in the oil supply side pilot oil passage increases, and the speed control valve enters the oil supply state. The switching operation is performed to switch the hydraulic motor to a large capacity state.

  Therefore, according to the third aspect of the present invention, the hydraulic motor is automatically switched between the small capacity state and the large capacity state by the driving load of the hydraulic motor, and the oil drain side pilot oil path and the oil supply side pilot oil path are provided. The control valve switching mechanism can be obtained simply with a simple structure, and the structure can be advantageously obtained in terms of cost.

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a self-propelled body 3 having a pair of left and right crawler type traveling devices 1 and a dozer device 2 is provided with a swivel base 6 having a driving unit 4 and a driving unit 5 so as to be capable of swiveling. A backhoe device 8 is connected to the front end of the swivel base 6 via a bracket 7 to form a backhoe with a dozer.

  As shown in FIG. 2, the output shaft 21a of the turning hydraulic motor 21 is linked to the turning operation shaft 11 of the turning operation mechanism 10 (see FIG. 3) for turning the turntable 6 via the planetary gear reduction mechanism 20. A hydraulic pump 25 is connected to the input port of the swing control valve 23 connected to the swing hydraulic motor 21 via a pair of hydraulic circuits 22, 22 via an oil supply path 24. A pilot hydraulic pump 29 is connected via a pilot oil supply passage 28 to an input port of a turning operation device 27 in which a pilot control valve (not shown) is connected to the pilot operation portion 23 a via a pilot operation oil passage 26. is there.

  A negative brake 30 is configured to act on the turning hydraulic motor 21, and an input port of the negative brake 30 is connected to an output port of the turning operation device 27 via a brake oil passage 31.

  When the pressure oil is discharged through the brake oil passage 31, the negative brake 30 is braked by the input operation force of the brake spring 32 and brakes on the output shaft 21 a of the swing hydraulic motor 21, whereby the negative brake 30 is applied to the swivel 6. When the brake oil enters the brake state and pressure oil is supplied from the brake oil passage 31, the release action is performed for pressurization by the pressure oil, and the brake action on the output shaft 21a of the swing hydraulic motor 21 is released. By this, it will be in a cutting state so that the braking action with respect to the turntable 6 may be cancelled | released.

  The swing hydraulic motor 21 is constituted by an axial plunger type hydraulic motor whose capacity can be changed by changing the swash plate angle. As shown in FIG. 2, the swing hydraulic motor 21 is provided with a speed change hydraulic cylinder 41. The operation mechanism 40 is linked.

  As shown in FIG. 2, the speed change operation mechanism 40 has an output port connected to the speed change hydraulic cylinder 41 linked to the capacity change operation portion 21 b of the swing hydraulic motor 21 via the speed change oil path 42. A speed control valve 43, a high pressure selection valve 45 having an output port connected to an input port of the speed control valve 43 via a delivery oil passage 44, and a control valve switching mechanism 46 linked to the speed control valve 43. It is configured.

  As shown in FIG. 3, the transmission hydraulic cylinder 41 is constituted by a single-acting hydraulic cylinder in which a piston 41 a is linked to a swash plate as a capacity changing operation portion 21 b of the swing hydraulic motor 21. The shift hydraulic cylinder 41 is urged toward the side of switching the swing hydraulic motor 21 to the small capacity state by a return force provided so that the capacity changing operation portion 21b of the swing hydraulic motor 21 automatically returns to the small capacity position H. As a result, the transmission hydraulic cylinder 41 is supplied with pressure oil from the speed control valve 43 and pressurized to a pressure higher than the set pressure determined by the urging force by the capacity changing operation portion 21b of the swing hydraulic motor 21, thereby increasing the capacity. When operated, the capacity changing operation portion 21b of the swing hydraulic motor 21 is switched to the large capacity position L to switch the swing hydraulic motor 21 to the large capacity state. The speed change hydraulic cylinder 41 is discharged to the small capacity side by discharging the pressure oil by the speed control valve 43, and the capacity changing operation portion 21b of the swing hydraulic motor 21 is switched to the small capacity position H by its return force. By operating, the swing hydraulic motor 21 is switched to the small capacity state.

  The speed control valve 43 can be switched between an oil supply state ON and an oil discharge state OF. When the speed control valve 43 is switched to the oil supply state ON, the hydraulic pressure from the high pressure selection valve 45 is transferred to the speed change hydraulic cylinder 41 via the speed change oil passage 42. When the oil is supplied and switched to the oil discharge state OF, the oil is discharged from the speed change hydraulic cylinder 41 via the speed change oil passage 42, and the waste oil flows into the oil discharge passage 47. The drain oil passage 48 is further joined to the drain oil passage 49 of the swing hydraulic motor 21.

  A pair of input portions of the high pressure selection valve 45 are communicated with the pair of hydraulic circuits 22 and 22 that drive the swing hydraulic motor 21 via the introduction oil passages 50 and 51, respectively. The hydraulic circuit 22 having a higher pressure is selected from the pair of hydraulic circuits 22 to drive the swing hydraulic motor 21, the hydraulic pressure is taken out from the high-pressure side hydraulic circuit 22, and this hydraulic pressure is sent via the delivery oil path 44. To the speed control valve 43.

  The control valve switching mechanism 46 includes an oil supply side pilot oil passage 46 a connected to one pilot operation portion 43 a of the speed control valve 43 and an oil supply side pilot oil connected to the other pilot operation portion 43 b of the speed control valve 43. And a path 46b. The oil supply side pilot oil passage 46b takes out the pilot oil pressure from the high pressure selection valve 45 from the delivery oil passage 44 and supplies it to the pilot operation portion 43b on the side where the speed control valve 43 is switched to the oil supply state ON. The oil drain side pilot oil passage 46a takes out the pilot oil pressure from the brake oil passage 31, and supplies it to the pilot operation portion 43a on the side where the speed control valve 43 is switched to the oil discharge state OF.

  That is, when the driving load of the swing hydraulic motor 21 becomes large, high-pressure pilot hydraulic pressure is supplied to the pilot operating portion 43b of the speed control valve 43 by the oil supply side pyro oil passage 46b, and the pilot oil pressure from the oil supply side pilot oil passage 46b By making the control valve switching operation force generated in the speed control valve 43 larger than the control valve switching operation force generated in the speed control valve 43 by the pilot oil pressure from the drain side pilot oil passage 46a, the control valve switching mechanism 46, the speed control valve 43 is switched to the oil supply state ON by the difference in the control valve switching operation force. On the other hand, when the driving load of the swing hydraulic motor 21 becomes small, a small pilot oil pressure is supplied to the pilot operating portion 43b of the speed control valve 43 by the oil supply side pyro oil passage 46b, and the oil pressure from the oil supply side pilot oil passage 46b. The control valve switching operation force generated in the speed control valve 43 by the pilot hydraulic pressure is made smaller than the control valve switching operation force generated in the speed control valve 43 by the pilot hydraulic pressure from the oil drain side pilot oil passage 46a. The valve switching mechanism 46 switches the speed control valve 43 to the oil discharge state OF by the difference in the control valve switching operation force.

  That is, when the turning lever 27a provided to the turning operation device 27 so as to be swingable is operated to the left turning position LE or the right turning position RI, the turning operation device 27 uses the pilot hydraulic pressure from the pilot hydraulic motor 29 as a pilot. Supplying to the pilot operating portion 23a of the turning control valve 23 via the operation oil passage 26, the turning control valve 23 is operated to switch to the left turn side or right turn side drive state corresponding to the operation position of the turn lever 27a, The swing control valve 23 supplies the hydraulic pressure from the hydraulic pump 25 to the swing hydraulic motor 21 via one hydraulic circuit 22, and the swing control valve 23 discharges the pressure oil discharged from the swing motor 21 to the other hydraulic circuit 22. Discharge into the oil passage 52. At this time, the turning operation device 27 supplies the pilot hydraulic pressure from the pilot hydraulic motor 29 to the negative brake 30 via the brake oil passage 31, and the negative brake 30 is turned off to release the braking action on the turntable 6. Yes. As a result, the turning hydraulic motor 21 is driven in the turning direction corresponding to the operation position of the turning lever 27a to drive the turning operation shaft 11 of the turning operation mechanism 10 via the speed reduction mechanism 20, and the turntable 6 is moved to the turning lever 27a. It is driven to turn leftward or rightward corresponding to the operation position.

  When the turning lever 27a of the turning operation device 27 is operated to the neutral position N, the turning operation device 27 drains oil from any pilot operation portion 23a of the turning control valve 23 via the pilot oil passage 26, and the turning control valve 23 The pressure oil supply to the swing hydraulic motor 21 is stopped in the neutral state. Thereby, the turning hydraulic motor 21 stops and the turning stand 6 stops. At this time, the turning operation device 27 drains oil from the negative brake 30 via the brake oil passage 31, and the negative brake 30 enters the engaged state, and the turntable 6 is braked.

  When the swivel base 6 is driven to the left turn side or the right turn side, the high pressure selection valve 45 extracts the hydraulic pressure from the hydraulic circuit 22 on the high pressure side for driving the swing hydraulic motor 21 to control the speed. Supply to valve 43. Further, the control valve switching mechanism 46 supplies the pilot hydraulic pressure from the high pressure selection valve 45 to the pilot operating portion 43b of the speed control valve 43 through the oil supply side pilot oil passage 46b, and the pilot from the brake oil passage 31 through the oil discharge side pilot oil passage 46a. The hydraulic pressure is supplied to the pilot operating portion 43a of the speed control valve 43, respectively.

  For this reason, the drive load of the swing hydraulic motor 21 is small, such as the bucket 8a (see FIG. 1) of the backhoe device 8 is lifted from the ground and is not subjected to the movement resistance due to the soil, so that the swivel 6 is swiveled. In some cases, the circuit pressure generated in the hydraulic circuit 22 becomes low, and the pilot hydraulic pressure supplied to the speed control valve 43 by the oil supply side pilot oil passage 46b becomes low, so that the speed control valve 43 enters the oil discharge state OF. When the switching hydraulic cylinder 41 is drained, the swing hydraulic motor 21 is switched to a small capacity state, the swing hydraulic motor 21 is driven at high speed, and the swivel base 6 can be driven to rotate at high speed.

  On the other hand, a circuit generated in the hydraulic circuit 22 when the driving load of the swing hydraulic motor 21 is large, for example, when the swivel 6 is swiveled to level the ground while the bucket 8a of the backhoe device 8 is used as a dozer means. Since the pressure becomes high and the pilot hydraulic pressure supplied to the speed control valve 43 through the oil supply side pilot oil passage 46b becomes high, the speed control valve 43 is switched to the oil supply state ON, and the speed change hydraulic cylinder 41 is oiled. Then, the swing hydraulic motor 21 is automatically switched to a state where the swing hydraulic motor 21 is driven at a low speed by switching the swing hydraulic motor 21 to a large capacity state, and the swivel base 6 can be driven to swing with high torque.

  The circuit pressure of the hydraulic circuit 22 on the high pressure side from which the hydraulic pressure is taken out by the high pressure selection valve 45 is the relief pressure of the relief valve 53 when the relief valve 53 provided in the hydraulic circuit 22 starts to wipe, and the relief valve 53 is fully opened. The speed control valve 43 is configured so that the swing hydraulic motor 21 is switched from the small capacity state to the large capacity state when the pressure becomes a pressure between the relief pressure of the relief valve 53 at the time. Thus, the swing hydraulic motor 21 can be switched between the small capacity state and the large capacity state while suppressing the occurrence of a shift shock as much as possible.

  As shown in FIG. 3, the turning operation mechanism 10 includes a turning race 12 supported by a self-propelled machine body 3, and the turning operation shaft 11 having a gear portion 11 a meshed with the turning race 12 is connected to a turntable. 6 is configured to be rotatably supported by a speed reduction case 13 fixed to 6.

  As shown in FIG. 3, the negative brake 30 has a brake disk 33 supported on a cylinder block 21 c of the swing hydraulic motor 21 so as to be integrally rotatable, and a brake piston 34 and a brake piston 34 in the motor case of the swing hydraulic motor 21. The brake spring 32 is provided.

  That is, when pressure oil is discharged from the brake piston 34 to the brake oil passage 31, the brake spring 32 presses the brake disc 33 against the motor case portion 35 via the brake piston 34, whereby the negative brake 30 is Then, it enters a state in which a friction brake is applied to the output shaft 21a of the swing hydraulic motor 21. When pressure oil is supplied to the brake piston 34 from the brake oil passage 31, the brake piston 34 is pressurized to compress the brake spring 32, and the brake spring 32 presses against the motor case portion 35 of the brake disc 33. To release. As a result, the negative brake 30 is turned off so as to release the braking applied to the output shaft 21 a of the swing hydraulic motor 21.

  As shown in FIG. 3, the speed control valve 43 and the high pressure selection valve 45 are mounted on the motor case of the swing hydraulic motor 21. The pair of relief valves 53 (see FIG. 2) of the hydraulic circuit 22 are disposed on the opposite side of the high pressure selection valve 45 and the speed control valve 43 with respect to the motor body including the cylinder block 21c of the swing hydraulic motor 21. It is attached to the motor case. Ports A, B, and M provided in the motor case of the swing hydraulic motor 21 as shown in FIG. 3 correspond to the ports A, B, and M shown in FIG.

[Another Example]
The present invention can be applied to excavation machines with various swivels such as a face excavator in addition to a backhoe. Therefore, the backhoe, the face shovel, etc. are collectively referred to as an excavator.

Overall side view of backhoe with dozer Hydraulic circuit diagram Sectional view of swivel operation mechanism and hydraulic motor

Explanation of symbols

6 Turntable 21 Variable displacement hydraulic motor 22 Hydraulic circuit 30 Negative brake 31 Brake oil passage 40 Shifting operation mechanism 41 Hydraulic cylinder 43 Speed control valve 45 High pressure selection valve 46 Control valve switching mechanism 46a Drain side pilot oil passage 46b Oil supply side pilot oil Road ON Oil supply state of speed control valve OF Oil discharge state of speed control valve

Claims (3)

An excavator with a swivel,
An excavator comprising a variable displacement hydraulic motor for turning the swivel base, and a shift operation mechanism for performing a capacity changing operation of the variable displacement hydraulic motor.   The shift operation mechanism is linked to a displacement changing operation unit of the variable displacement hydraulic motor, and is urged to switch the variable displacement hydraulic motor to a small displacement state, and supplies oil to the hydraulic cylinder. Provided with a speed control valve that can be switched between an oil supply state and an oil discharge state in which oil is discharged from the hydraulic cylinder, and when the driving load of the variable displacement hydraulic motor is large, the speed control valve is in an oil supply state. A control valve switching mechanism for switching the speed control valve according to the drive load of the variable capacity hydraulic motor so that the speed control valve is in an oil drained state when the drive load of the variable capacity hydraulic motor is small. The excavator according to claim 1, wherein the excavator is provided. Provide a negative rake that brakes the swivel,
Selecting a high pressure side hydraulic circuit from a pair of hydraulic circuits for driving the variable displacement hydraulic motor, and providing a high pressure selection valve for taking out the hydraulic pressure from the selected high pressure side hydraulic circuit and supplying the hydraulic pressure to the speed control valve;
The control valve switching mechanism is a drain-side pilot oil passage that takes out pilot hydraulic pressure from a brake fluid passage that operates the negative rake and supplies the speed control valve to a drain oil state so as to switch the speed control valve to a drain oil state. The excavator according to claim 2, further comprising an oil supply side pilot oil passage for taking out the pilot oil pressure from the valve and supplying the speed control valve to the oil supply state so as to switch the speed control valve to an oil supply state.

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