JP2005265015A - Construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable for even one operator to quickly operate a hydraulic actuator if needed while an engine stops in a construction machine having an engine using compressed gas as fuel mounted thereon. <P>SOLUTION: An auxiliary pilot line 21 is branched off of a pilot line 18 on a boom lowering side of a hydraulic pilot type control valve 16 and an accumulator 23, a stop valve 22 and a gas pressure introducing port 24 are provided on the auxiliary pilot line 21. A branch pipe 26 and a gas taking out port 28 for taking out compressed gas are provided. The gas pressure introducing port 24 and the gas pressure taking out port 28 are connected while the engine stops and hydraulic pressure generated in the accumulator 23 by introduced gas pressure is sent to a boom lowering side port 16a of the control valve 16 to enable to switch the control valve 16 to the boom lowering side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a construction machine equipped with a prime mover that uses compressed gas such as compressed natural gas as fuel.

  In recent years, from the viewpoint of energy measures and environmental measures, it has been studied to use compressed gas such as compressed natural gas as a prime mover fuel not only in automobiles but also in construction machines such as excavators.

  In the case of a system that operates an engine with compressed natural gas (CNG), compressed natural gas (hereinafter simply referred to as gas) is stored in a gas container at a high pressure of about 20 MPa, and the gas discharged from the gas container is decompressed. The pressure is reduced to a pressure suitable for engine fuel (about 0.4 Mpa) by the valve and supplied to the engine.

  In the case of construction machinery, the engine is driven by a hydraulic pump, and the hydraulic actuator is operated by oil discharged from the hydraulic pump.

  A description will be given using a hydraulic excavator as an example.

  As shown in FIG. 4, the excavator includes an upper swing body 2 mounted on a crawler-type lower traveling body 1, and a work (excavation) attachment 3 attached to the upper swing body 2.

  The work attachment 3 includes a boom 4, an arm 5 and a bucket 6, and boom, arm, and bucket cylinders 7, 8, and 9 as hydraulic actuators for operating the boom 4, the arm 5 and the bucket. Both the traveling motors are driven by the oil discharged from the hydraulic pump to perform operations such as excavation. Reference numeral 10 denotes a cabin (operator's cab) provided in the upper swing body 2.

  In this hydraulic excavator, when the engine stops due to an engine trouble or the like, the hydraulic pump stops, the hydraulic source of the hydraulic actuator is lost, and the movement of the entire machine stops. In this case, for example, it is not preferable to stop the attachment 3 while it is raised, so it is necessary to take emergency measures such as lowering the attachment 3 to the ground.

As a countermeasure against this point, as disclosed in Patent Document 1, there is a technique in which a manual pump is connected to a pilot line of a hydraulic pilot type control valve that controls the operation of a hydraulic actuator, and the control valve is switched by this manual pump. Proposed.
JP 2001-336177 A

  However, according to this known technique, the control valve is switched only when the manual pump is connected to the pilot line and the pump is operated, and the hydraulic actuator is activated (for example, the boom is lowered), so that a quick response cannot be made. In addition, a person who operates the manual pump and a person who monitors the movement of the resulting attachment are required. Due to these operational constraints, they may not function in an emergency.

  An object of the present invention is to enable a hydraulic actuator to be quickly operated by one operator as needed in a construction machine equipped with a prime mover using compressed gas as fuel when the prime mover is stopped. .

  The invention according to claim 1 is a construction machine that operates a prime mover using compressed gas as fuel, drives a hydraulic pump by the prime mover, and operates a hydraulic actuator by hydraulic oil discharged from the hydraulic pump. Support means for operating the hydraulic actuator sometimes using the compressed gas as a pressure source is provided.

  According to a second aspect of the present invention, in the configuration of the first aspect, the support means includes a hydraulic pilot type actuator control valve that controls the operation of the hydraulic actuator, a pressure converter that converts the pressure of the compressed gas into hydraulic pressure, A pilot valve that sends the hydraulic pressure converted by the pressure converter to the actuator control valve as a pilot pressure when the prime mover is stopped.

  According to a third aspect of the present invention, in the configuration of the second aspect, the actuator control valve has a holding pressure release position for releasing the holding pressure of the hydraulic actuator into the tank, and the pilot valve has the actuator control valve at the holding pressure release position. It is comprised so that the pilot pressure for switching to may be sent.

  According to a fourth aspect of the present invention, in the configuration of the second or third aspect, the hydraulic pilot type control valve that controls the operation of the hydraulic actuator during operation of the prime mover is also used as the actuator control valve when the prime mover is stopped. It is.

  According to a fifth aspect of the present invention, in the configuration of any of the second to fourth aspects, a stop valve that is manually operated is used as a pilot valve.

  According to a sixth aspect of the present invention, there is provided a remote control valve for controlling the operation of the actuator control valve during operation of the prime mover, and the remote control valve is also used as a pilot valve when the prime mover is stopped. It has been done.

  A seventh aspect of the present invention provides a gas pressure extracting port for extracting a gas pressure from a compressed gas supply source, a gas pressure introducing port for introducing the gas pressure into the support means, and A connecting pipe for detachably connecting both ports is provided.

  According to the present invention, paying attention to the fact that a fuel gas of a constant pressure is always provided in a system using a compressed gas as a prime mover fuel, the hydraulic actuator is operated by the support means using the pressure of the fuel gas (claim). 3, for example, the work attachment is lowered by removing the holding pressure of the hydraulic actuator into the tank), so that one operator can quickly respond to the emergency operation of the actuator when the prime mover is stopped.

  According to the second to sixth aspects of the present invention, the hydraulic actuator can be accurately actuated as desired by a rich hydraulic device such as an actuator control valve, a pressure transducer, and a pilot valve.

  In this case, since the control valve is used as an actuator control valve in the invention of claim 4 and the remote control valve is used as a pilot valve in the invention of claim 6, the actuator control valve and the pilot valve are added exclusively for emergency use. Compared to the case, the equipment can be simplified and the cost can be reduced. In addition, unlike the case where the manual pump is operated at a location away from the driver's seat, it can be operated from the driver's seat even when the prime mover is stopped, so that it can be dealt with more quickly and easily.

  On the other hand, according to the invention of claim 7, the support means works unnecessarily by connecting the gas pressure take-out port and the gas pressure introduction port only when the prime mover is stopped and separating them during the prime mover operation. The situation can be avoided.

1st Embodiment (refer FIG. 1)
FIG. 1 shows the overall configuration of a system in which a hydraulic pump is driven by an engine using compressed natural gas as fuel.

  In the figure, 11 is a gas cylinder as a gas supply source. A compressed natural gas (hereinafter simply referred to as gas) stored in the gas cylinder 11 at a high pressure of about 20 Mpa is a pressure suitable for engine fuel by a pressure reducing valve 12. After being depressurized to about 4 MPa, it is supplied to the engine 13.

  The engine 13 is operated using the gas as a fuel, and the main and auxiliary hydraulic pumps 14 and 15 are driven by the engine 13.

  The pressure oil discharged from the main hydraulic pump 14 is sent to a hydraulic actuator (explained here in the case of the boom cylinder 7 in FIG. 4) via a hydraulic pilot type control valve 16 as an actuator control valve. The boom cylinder 7 is operated. The oil discharged from the boom cylinder 7 is returned to the hydraulic oil tank T.

  The control valve 16 is switched between the neutral position A, the boom lowering position B, and the boom raising position C by the pilot pressure from the remote control valve 17 using the auxiliary hydraulic pump 15 as a pressure source, and the boom cylinder 7 is operated. Then, the reduction operation is performed at the boom lowering position B, and the expansion operation is performed at the boom raising position C.

  Here, in the state where the work attachment 3 of FIG. 4 is stopped in the air, a holding pressure for supporting the weight of the attachment is generated in the extension side oil chamber 7a of the boom cylinder 7. Accordingly, the entire work attachment 3 can be lowered by removing this holding pressure into the tank T when the engine is stopped.

  The remote control valve 17 and the boom lowering side and boom raising side pilot ports 16a and 16b of the control valve 16 are connected by both the boom lowering side and boom raising side pilot lines 18 and 19, and according to the operation amount of the remote control valve 17. The pilot pressure is sent to the control valve 16 through the pilot lines 18 and 19.

  A manual first stop valve 20 is provided at the boom lowering pilot line 18 of the pilot lines 18 and 19, and an auxiliary pilot line 21 for branching off from the pilot line 18 is connected to the pilot line 18. ing.

  The auxiliary pilot line 21 is provided with a second stop valve 22 and an accumulator 23 as a pressure converter, and a gas pressure introduction port 24 is provided on the inlet side of the accumulator 23.

  On the other hand, a branch line 26 is connected to a high pressure gas line 25 connecting the gas cylinder 11 and the pressure reducing valve 12.

  The branch line 26 is provided with a third stop valve 27, and a gas pressure take-out port 28 is provided at the tip thereof.

  In this configuration, during engine operation, the first stop valve 20 is opened, and the second and third stop valves 22, 27 are closed.

  In this state, the control valve 16 is switched and operated by operating the remote control valve 17, and the boom cylinder 7 is operated by the discharged oil from the main hydraulic pump 14 to perform normal work.

  On the other hand, when the engine 13 is stopped due to an engine trouble or the like, and the attachment 3 remains stopped in the air at this time, it becomes necessary to lower it to the ground.

  The gas pressure take-out port 28 and the gas pressure introduction port 24 are connected by a connecting pipe 29, the first stop valve 20 is closed, and both the second and third stop valves 22, 27 are opened.

  As a result, the compressed gas from the gas cylinder 11 is introduced into the auxiliary pilot line 21, and the hydraulic pressure that is constantly pressurized by the compressed gas from the accumulator 23 is sent to the boom lowering pilot port 16 a of the control valve 16.

  That is, support means for operating the boom cylinder 7 by converting the pressure of the fuel gas into hydraulic pressure when the engine is stopped is configured, and the control valve 16 is switched to the boom lowering position B without the operation of the remote control valve 17 by this support means. Instead, as described above, the pressure in the expansion side oil chamber (holding side oil chamber) 7a of the boom cylinder 7 is released to the tank T through the control valve 7, so that the boom cylinder 7 is reduced by the weight of the attachment. The work attachment 3 is lowered.

  At this time, the stroke of the control valve 7 can be controlled by manually adjusting the opening degree of the second stop valve 22, so that the lowering speed can be adjusted as necessary.

  In addition, after the attachment lowering operation is finished, both the second and third stop valves 22 and 27 are closed, the first stop valve 20 is opened, and the connection pipe 29 is removed to prepare for the restoration of the engine 13.

  As described above, when the engine is stopped, the control valve 16 is operated using the gas pressure that is a pressure source unique to the gas engine, and the boom cylinder 7 is operated to the boom lowering side. The boom lowering operation can be performed immediately by simply opening and closing 20, 22, 27. That is, even one operator can quickly respond in an emergency.

  During the engine operation, the gas pressure take-out port 28 and the gas pressure introduction port 24 can be disconnected, so that the stop valves 22 and 27 are loosened and the pilot pressure is sent from the auxiliary pilot line 21 to the control valve 16. There is no risk of unforeseen circumstances.

Second embodiment (see FIG. 2)
In both the following second and third embodiments, only differences from the first embodiment will be described.

  In the second embodiment, the auxiliary pilot line 21 is branched and connected to the remote control valve primary side line 30 connecting the auxiliary hydraulic pump 15 and the remote control valve 17, and the hydraulic pressure from the accumulator 23 is supplied to the remote control valve 17 as the primary pressure. Configured to get.

  By doing so, since the control of the control valve 16 by the remote control valve 17 is ensured even when the engine is stopped, the control valve 16 can be switched not only to the boom lowering position B but also to the boom raising position C.

  That is, the boom cylinder 7 can be operated on both the lower side and the upper side as in the engine operation.

  Further, since the remote control valve 17 is also used as a pilot valve when the engine is stopped, unlike the case where the manual pump is operated away from the driver's seat, it can be operated from the driver's seat as it is when the engine is stopped. It can be easily dealt with.

  In the second embodiment, the first stop valve 20 of the first embodiment is not necessary. Further, the second stop valve 22 is not required to have the function of adjusting the opening degree of the auxiliary pilot line 21 as in the first embodiment, and is merely required to open and close the line 21. It may be provided accordingly.

  In order to prevent the hydraulic pressure from the auxiliary pilot line 21 from being sent to the auxiliary hydraulic pump 15 side, it is desirable to provide a check valve 31 on the discharge side of the pump 15 as shown.

Third embodiment (see FIG. 3)
In the third embodiment, a pressure transducer 32 having a cylinder structure is provided in the auxiliary pilot line 21 instead of the accumulator 23 of both the first and second embodiments.

  The pressure converter 32 includes a gas pressure chamber 34 on one side of the piston 33 and a hydraulic chamber 35 on the opposite side, and pushes the piston 33 by the gas pressure introduced into the gas pressure chamber 34 to generate hydraulic pressure in the hydraulic chamber 35. It is configured as follows.

  Reference numeral 36 denotes an oil replenishment pipeline for replenishing oil from the tank T to the hydraulic chamber 35, and 37 is a check valve provided in the pipeline 36.

  Also with this configuration, basically the same effect as both the first and second embodiments can be obtained.

  Here, as in the second embodiment, the hydraulic pressure generated by the pressure transducer 31 is sent to the primary side pipe 30 of the remote control valve 17, but as in the first embodiment shown in FIG. You may comprise so that it may send to the boom lowering side pilot port 16a of the control valve 16. FIG.

Other embodiments
(1) In the above embodiments, the boom cylinder 7 is exemplified as the hydraulic actuator that is operated when the engine is stopped. However, the same applies to the other hydraulic actuators (arm cylinder 8 or bucket cylinder 9) of the work attachment 3 shown in FIG. Can be applied to.

  (2) In each of the above embodiments, the gas pressure take-out port 28 and the gas pressure introduction port 24 are connected by the connection pipe 29 when the engine is stopped. However, both the ports 28 and 24 may be always connected. .

  (3) In each of the above embodiments, the existing control valve 16 is also used as an actuator control valve for controlling the operation of the hydraulic actuator when the engine is stopped. A control valve may be connected in parallel with the control valve 16.

  (4) When the engine is stopped, a stop valve 22 is used in the first embodiment as a pilot valve that sends the hydraulic pressure converted by the pressure converter as a pilot pressure to the actuator control valve (control valve 16 in each embodiment). In the third and second embodiments, the existing remote control valve 17 is also used. However, a remote control valve dedicated to stopping the engine may be provided.

  (5) The present invention can also be applied to a construction machine using an engine that uses compressed gas (LP gas, hydrogen, etc.) other than natural gas as fuel.

  In addition, even when a system that drives a hydraulic pump by rotating an electric motor with a fuel cell is used, it is common in that the prime mover may stop due to the use of compressed gas as a fuel and a motor trouble or the like. Can also be applied to construction machines using this fuel cell engine as a prime mover.

It is a system configuration figure showing a 1st embodiment of the present invention. It is a system configuration figure showing a 2nd embodiment of the present invention. It is a system configuration figure showing a 3rd embodiment of the present invention. 1 is a schematic side view of a hydraulic excavator that is an example to which the present invention is applied.

Explanation of symbols

11 Gas cylinder (gas supply source)
13 Engine as prime mover 14 Main hydraulic pump 15 Auxiliary hydraulic pump 16 Control valve as actuator control valve 17 Remote control valve (pilot valve)
DESCRIPTION OF SYMBOLS 21 Auxiliary pilot line 22 Stop valve as pilot valve 23 Accumulator as pressure converter 24 Gas pressure introduction port 27 Gas pressure extraction port 29 Connection pipe 31 Pressure converter

Claims (7)

  In a construction machine that operates a prime mover using compressed gas as a fuel, drives a hydraulic pump by the prime mover, and operates a hydraulic actuator by hydraulic oil discharged from the hydraulic pump, the compressed gas is supplied as a pressure source when the prime mover is stopped. A construction machine comprising a support means for operating the hydraulic actuator.   2. The construction machine according to claim 1, wherein the support means includes a hydraulic pilot type actuator control valve that controls the operation of the hydraulic actuator, a pressure converter that converts the pressure of the compressed gas into hydraulic pressure, and when the prime mover is stopped. A construction machine comprising: a pilot valve that sends the hydraulic pressure converted by the pressure converter as a pilot pressure to the actuator control valve.   3. The construction machine according to claim 2, wherein the actuator control valve has a holding pressure release position for releasing the holding pressure of the hydraulic actuator into the tank, and the pilot valve is used for switching the actuator control valve to the holding pressure release position. A construction machine configured to send pilot pressure.   4. The construction machine according to claim 2, wherein a hydraulic pilot type control valve that controls the operation of the hydraulic actuator during operation of the prime mover is also used as an actuator control valve when the prime mover is stopped. machine.   The construction machine according to any one of claims 2 to 4, wherein a stop valve that is manually operated is used as a pilot valve.   6. The construction machine according to claim 2, further comprising a remote control valve that controls the operation of the actuator control valve during operation of the prime mover, and the remote control valve is also used as a pilot valve when the prime mover is stopped. A construction machine characterized by being constructed.   The construction machine according to any one of claims 1 to 6, wherein a gas pressure extraction port for extracting a gas pressure from a compressed gas supply source, a gas pressure introduction port for introducing the gas pressure into the support means, and both ports A construction machine characterized in that a connecting pipe for detachably connecting each other is provided.

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