JP2010014152A - Working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working vehicle suppressing the excessive rise of temperature of a hydraulic fluid supplied to a working hydraulic actuator. <P>SOLUTION: The working vehicle comprises: a traveling hydraulic actuator 17; a traveling hydraulic pump 4 for driving the traveling hydraulic actuator 17; a first tank T1, to which the hydraulic fluid of a traveling hydraulic circuit for driving the traveling hydraulic actuator 17 is returned by the traveling hydraulic pump 4; a working hydraulic actuator 6; a working hydraulic pump 3 for driving the working hydraulic actuator 6; and a second tank T2 which is formed separately from the first tank T1, and in which the hydraulic fluid supplied to the working hydraulic pump 3 is stored. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a working vehicle including a traveling hydraulic actuator and a working hydraulic actuator.

Conventionally, as a work vehicle including a traveling hydraulic actuator and a working hydraulic actuator, the one described in Patent Document 1 is known.
An upper-slewing hydraulic traveling vehicle described in Patent Document 1 includes a working hydraulic circuit that drives a working hydraulic actuator using a working hydraulic pump as a hydraulic source, a traveling hydraulic motor, and a traveling hydraulic pump via a swivel joint. A closed circuit travel circuit and an oil tank. The oil in the oil tank is sucked up into the working hydraulic circuit and the traveling circuit. Moreover, the return oil which came out from the actuator of the working hydraulic circuit and the surplus oil from the traveling circuit return to the oil tank.
According to this configuration, the driving hydraulic actuator and the working hydraulic actuator are driven by the oil in one oil tank.

JP 2004-347083 A

  However, as described in Patent Document 1, the oil in one oil tank is supplied to both the traveling hydraulic actuator and the working hydraulic actuator, and return oil from both actuators is used as the one oil. When the structure discharged to the tank is applied to, for example, a hydraulic traveling crane equipped with an extendable boom that is expanded and contracted by a hydraulic cylinder, the following problem occurs.

In a hydraulic traveling crane equipped with a telescopic boom, when the hydraulic cylinder is driven to extend the telescopic boom after traveling, hydraulic oil that has become hot due to the driving of the traveling hydraulic actuator is supplied to the hydraulic cylinder. Become. In this case, as the temperature of the working oil decreases with the passage of time, the working oil tends to thermally contract, and negative pressure is generated in the hydraulic cylinder.
Here, the telescopic boom is usually configured by nesting a plurality of unit booms, and the plurality of unit booms are in contact with each other via a sliding pad. For this reason, even if the temperature of the hydraulic oil decreases, the telescopic boom does not immediately shrink due to the static frictional force of the sliding pad, and negative pressure is generated in the hydraulic cylinder. And if the contraction force by the negative pressure in a hydraulic cylinder exceeds the static frictional force between unit booms, a hydraulic cylinder will shrink at a stretch. As a result, a large impact sound is generated and there is a risk that not only the telescopic mechanism but also the boom itself may be damaged.

  Further, not only in the boom extension / contraction hydraulic cylinder, for example, in the raising / lowering cylinder for raising / lowering the boom, the raising / lowering angle of the boom gradually changes due to the generation of the negative pressure accompanying the temperature drop of the hydraulic oil. There is a problem.

  As described above, according to the configuration of Patent Document 1, when the working hydraulic actuator is driven after traveling, the hydraulic oil that has become hot due to the driving of the traveling hydraulic actuator is supplied to the working hydraulic actuator. Then, when the oil temperature of the working oil decreases with the passage of time, the working oil contracts, which may hinder the driving of the working hydraulic actuator.

  In view of the above circumstances, an object of the present invention is to provide a work vehicle capable of suppressing the operating oil supplied to the working hydraulic actuator from becoming excessively high in temperature.

Means and effects for solving the problems

  The present invention relates to a working vehicle including a traveling hydraulic actuator and a working hydraulic actuator. And the work vehicle which concerns on this invention has the following some features in order to achieve the said objective. That is, the work vehicle of the present invention includes the following features alone or in combination as appropriate.

  In order to achieve the above object, the first feature of the work vehicle according to the present invention is that a travel hydraulic actuator, a travel hydraulic pump for driving the travel hydraulic actuator, and the travel hydraulic pump drive the travel. A first reservoir in which hydraulic fluid of a traveling hydraulic circuit for driving the hydraulic actuator is returned, a working hydraulic actuator, a working hydraulic pump for driving the working hydraulic actuator, and the working hydraulic pressure A second reservoir that stores hydraulic oil supplied to the pump, and the first reservoir and the second reservoir are separated.

  According to this configuration, since the first reservoir that returns high-temperature hydraulic fluid from the traveling hydraulic circuit during traveling and the second reservoir that stores hydraulic fluid supplied to the working hydraulic pump are separated, At least heat transfer from the first reservoir to the second reservoir due to convection of the hydraulic oil is suppressed, and the hydraulic oil supplied to the work hydraulic actuator via the work hydraulic pump can be prevented from becoming excessively hot. It is.

  Further, a second feature of the work vehicle according to the present invention is the work vehicle having the first feature, wherein the first storage portion is a storage portion that stores hydraulic oil supplied to the traveling hydraulic circuit. And the capacity | capacitance of the said 1st storage part is that it is smaller than the capacity | capacitance of a said 2nd storage part.

  According to this structure, the temperature of the hydraulic oil used at the time of driving | running | working can be raised rapidly to a suitable temperature. Thereby, piping pressure loss can be reduced and it becomes possible to improve driving | running | working fuel consumption.

  Moreover, the 3rd characteristic in the work vehicle which concerns on this invention overflowed from one storage part among the said 1st storage part and the said 2nd storage part in a work vehicle provided with a 1st characteristic or a 2nd characteristic. A communication oil path is provided between the first reservoir and the second reservoir so that the hydraulic oil is introduced into the other reservoir.

  According to this configuration, when the hydraulic oil is supplied to the first storage part beyond the predetermined amount, the hydraulic oil in the first storage part is guided to the second storage part. The hydraulic oil can be prevented from being supplied beyond the capacity to the first reservoir.

  According to a fourth feature of the work vehicle according to the present invention, in the work vehicle having the third feature, the working hydraulic circuit hydraulic oil for driving the work hydraulic actuator by the work hydraulic pump, A first return oil passage for returning the hydraulic oil of the traveling hydraulic circuit to the first reservoir, and a second return oil passage for returning the hydraulic oil of the working hydraulic circuit to the second reservoir. And a cooling means for cooling the working oil is provided only in the first return oil passage among the first return oil passage and the second return oil passage.

  According to this configuration, the hydraulic oil in the working hydraulic circuit and the traveling hydraulic circuit can be cooled by the cooling means provided in the first return oil passage and returned to the first storage unit. Thus, the hydraulic fluid that returns from the working hydraulic circuit and the traveling hydraulic circuit to the storage section can be cooled without providing a plurality of cooling means in the oil passage that returns from the working hydraulic circuit and the traveling hydraulic circuit to the storage section. Can do. As a result, the installation space and installation cost of the cooling means can be reduced.

  Further, a fifth feature of the work vehicle according to the present invention is the work vehicle having the third feature or the fourth feature, wherein the first storage unit and the second storage unit are stored inside one tank. The space is formed by partitioning with a partition plate having a heat insulating structure, and the communication oil passage is a through-hole formed in the partition plate.

  According to this configuration, the heat transfer from one reservoir to another reservoir can be reduced by the partition plate between the two reservoirs having a heat insulating structure, and the operation supplied to the working hydraulic actuator It can prevent more reliably that oil becomes high temperature too much. Moreover, a communication oil path can be simply formed by comprising a communication oil path as a through-hole formed in the partition plate.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
In the following embodiments, a case where the present invention is applied to a rough terrain crane (work vehicle) having a telescopic boom will be described as an example.

(First embodiment)
FIG. 1 is a hydraulic circuit configuration diagram of a rough terrain crane according to a first embodiment of the present invention.
As shown in FIG. 1, the rough terrain crane according to the first embodiment includes a prime mover 1. The prime mover 1 drives the working hydraulic pump 3 and the traveling hydraulic pump 4 via the power distributor 2.

  The rough terrain crane includes two tanks T1 and T2 for storing hydraulic oil. The tank T1 (first storage unit) is a tank that stores hydraulic oil used during traveling, and the tank T2 (second storage unit) is a tank that stores hydraulic oil used during crane work. The two tanks T1, T2 are arranged so as to be thermally insulated between the two tanks. In the present embodiment, the capacity of the tank T1 is about 150L, and the capacity of the tank T2 is about 350L.

<Working hydraulic circuit>
The work hydraulic pump 3 is configured as a variable displacement pump whose tilt angle is controlled by a work pump regulator 5. The hydraulic cylinder 6 (working hydraulic actuator) for extending and retracting the boom is driven by the hydraulic oil sucked from the tank T2 by the working hydraulic pump 3 through the suction oil passage 30.

The work pump regulator 5 is connected to a pilot pressure source 9 via an electromagnetic switching valve 8 controlled by a controller 7. The controller 7 is configured to transmit travel speed information detected by the speed sensor 10 that measures the travel speed. The controller 7 switches the electromagnetic switching valve 8 based on the traveling speed information from the speed sensor 10 to communicate or block the pilot pressure source 9 and the work pump regulator 5. As a result, the operation stroke of the working pump regulator 5 changes and the magnitude of the pump tilt angle is controlled. Specifically, based on the traveling speed information from the speed sensor 10, the controller 7 is an electromagnetic switching valve that causes the pilot pressure source 9 and the work pump regulator 5 to communicate with each other when the traveling speed exceeds 10 km / h. Switch 8 Thereby, when the traveling speed exceeds 10 km / h, the working hydraulic pump 3 is controlled so that the pump tilt angle becomes small.
The electromagnetic switching valve 8 may be switched by ON / OFF of a work switch or remote control pressure of an operation lever of a crane.

  The working hydraulic circuit for driving the hydraulic cylinder 6 using the working hydraulic pump 3 as a hydraulic source is provided with a switching valve 11, a counter balance valve 12, and a relief valve 13.

The switching valve 11 is a three-position 6-port switching valve disposed between the working hydraulic pump 3 and the hydraulic cylinder 6.
Three ports on the working hydraulic pump 3 side of the switching valve 11 have an oil passage 31 communicating with the working hydraulic pump 3, an oil passage 32 branched from the oil passage 31, and an oil communicating with the return oil passage 34. The path 33 is connected to each other. The return oil passage 34 is an oil passage communicating with the tank T2.

  In addition, an oil passage 35 communicating with the return oil passage 34 and an oil passage 36 communicating with the bottom chamber 6a of the hydraulic cylinder 6 via the counter balance valve 12 are connected to the three ports on the hydraulic cylinder 6 side of the switching valve 11. An oil passage 37 communicating with the rod chamber 6b of the hydraulic cylinder 6 is connected via the counter balance valve 12.

  The counter balance valve 12 acts on a check valve 12a interposed in the oil passage 36, a relief valve 12b provided in an oil passage that bypasses the check valve 12a, and a pilot pressure from the oil passage 37 acting on the relief valve 12b. And a pilot oil passage 12c. The relief valve 12b switches so as to open an oil path that bypasses the check valve 12a when the pilot pressure acting via the pilot oil path 12c exceeds a predetermined pressure.

The switching valve 11 can be switched to one of the first position 11a, the second position 11b, and the third position 11c based on the operation of the shift lever by the operator.
In the first position 11a, the oil passage 32 and the oil passage 36 are communicated, the oil passage 33 and the oil passage 37 are communicated, and the port to which the oil passage 31 and the oil passage 35 are connected is blocked.
In the second position 11b, the oil passage 31 and the oil passage 35 are communicated, the oil passage 33 and the oil passage 37 are communicated, and the port to which the oil passage 32 and the oil passage 36 are connected is blocked.
In the third position 11c, the oil passage 32 and the oil passage 37 are communicated, the oil passage 33 and the oil passage 36 are communicated, and the port to which the oil passage 31 and the oil passage 35 are connected is blocked.

With such a configuration of the switching valve 11, by switching the switching valve 11 to the first position 11a, the pressure oil from the working hydraulic pump 3 is supplied to the bottom chamber 6a of the hydraulic cylinder 6 via the check valve 12a. At the same time, the hydraulic oil in the rod chamber 6 b is discharged to the return oil passage 34. Thereby, the hydraulic cylinder 6 can be extended and the telescopic boom can be extended.
On the other hand, by switching the switching valve 11 to the third position 11c, a pilot pressure is generated in the oil passage 37 and the pilot oil passage 12c, and the relief valve 12b is opened. Thereby, the pressure oil from the working hydraulic pump 3 is supplied to the rod chamber 6b of the hydraulic cylinder 6, and the hydraulic oil in the bottom chamber 6a of the hydraulic cylinder 6 is discharged to the return oil passage 34 via the relief valve 12b. The Thereby, the hydraulic cylinder 6 can be contracted and the telescopic boom can be contracted.
When the switching valve 11 is in the second position 11b, the working oil from the working hydraulic pump 3 is caused to flow to the return oil passage 34 via the oil passage 31 and the oil passage 35, and the hydraulic cylinder 6 is supplied with the working oil. Is not supplied. Further, the hydraulic oil discharge path of the bottom chamber 6a of the hydraulic cylinder 6 is blocked. Therefore, the hydraulic cylinder 6 does not contract, and the telescopic boom is held at a predetermined length.

  An oil cooler 14 is provided in the return oil passage 34 of the working hydraulic circuit. The hydraulic oil discharged from the hydraulic cylinder 6 of the working hydraulic circuit and the hydraulic oil discharged via the oil passage 35 and the relief valve 13 are cooled by the oil cooler 14 and returned to the tank T2. Further, a filter 15 for removing impurities mixed in the hydraulic oil is provided on the tank T2 side of the return oil passage 34 with respect to the oil cooler 14.

  The relief valve 13 is provided between the oil passage 38 branched from the oil passage 31 and the return oil passage 34. The relief valve 13 is configured to release hydraulic oil to the return oil passage 34 when the hydraulic pressure of the circuit on the discharge side of the working hydraulic pump 3 exceeds a predetermined pressure.

<Travel hydraulic circuit>
The traveling hydraulic pump 4 is configured as a bidirectional variable displacement pump. The tilt angle of the traveling hydraulic pump 4 is controlled by the controller 7 via a traveling pump regulator and an electromagnetic switching valve (not shown). The travel hydraulic pump 4 drives a travel hydraulic motor 17 (travel hydraulic actuator). The traveling hydraulic motor 17 is connected to a traveling speed reducer (not shown) that reduces the rotational force of the traveling hydraulic motor 17 and transmits it to the traveling drive wheels.

  The traveling hydraulic circuit constituting the HST (Hydro Static Transmission) system for driving the traveling hydraulic motor 17 using the traveling hydraulic pump 4 as a hydraulic source is connected to the traveling hydraulic circuit from the tank T1 via the suction oil passage 40. Overload that regulates the maximum value of pressure in the circuits 41 and 42 between the fixed displacement type oil supply pump 18 that sucks oil into the hydraulic circuit, the relief valve 19, the traveling hydraulic pump 4 and the traveling hydraulic motor 17. There are provided relief valves 20 and 20, check valves 21 and 21 for replenishing a part of oil from the oil replenishment pump 18 to the circuits 41 and 42, and a flushing valve 22 for discharging excess oil out of the circuit. Yes.

  Further, a return oil passage through which leakage oil from the traveling hydraulic pump 4, relief oil from the relief valve 19, leakage oil from the traveling hydraulic motor 17, and discharged oil from the flushing valve 22 flows into the traveling hydraulic circuit. 43 is provided. The return oil passage 43 is connected to the tank T <b> 1 via the merged return oil passage 45.

  The combined return oil passage 45 is an oil passage through which hydraulic oil from the return oil passage 43 and a return oil passage 44 from another traveling system hydraulic system 50 described later flows and flows to the tank T1. The merging return oil passage 45 is provided with an oil cooler 23, which can cool the hydraulic oil returning to the tank T1. Further, a filter 24 for removing impurities mixed in the hydraulic oil is provided on the tank T1 side of the combined return oil passage 45 from the oil cooler 23.

  The hydraulic oil is also supplied from the tank T1 to another traveling hydraulic system 50 such as a steering hydraulic actuator. The return oil passage 44 from the other traveling hydraulic system 50 is connected to the merging return oil passage 45. In FIG. 1, reference numeral 50 and reference numeral 50 ′ indicate the same traveling hydraulic system.

  In the above configuration, when a shift lever (not shown) is operated, the tilt angle of the traveling hydraulic pump 4 is increased by a signal from the controller 7 based on the operation signal. As a result, the hydraulic oil discharged from the traveling hydraulic pump 4 is sent to the traveling hydraulic motor 17, the traveling hydraulic motor 17 rotates, and the vehicle travels. During traveling, normally, the boom does not expand and contract, so the switching valve 11 of the working hydraulic circuit is held at the second position 11b.

  During this traveling, the hydraulic fluid leaking from the traveling hydraulic pump 4 and the traveling hydraulic motor 17 and the hydraulic fluid discharged through the relief valve 19 and the flushing valve 22 are passed through the return oil passage 43 and the merged return oil passage 45. Through the tank T1. Further, the hydraulic oil from the other traveling hydraulic system 50 is also returned to the tank T <b> 1 through the return oil passage 44 and the merged return oil passage 45.

  Meanwhile, at this time, the working hydraulic pump 3 is driven together with the traveling hydraulic pump 4, and the oil discharged from the working hydraulic pump 3 flows into the return oil passage 34 via the second position 11 b of the switching valve 11. Then, it is cooled by the oil cooler 14 and circulates to the tank T2 and further to the working hydraulic pump 3. Here, when the traveling speed of the vehicle exceeds 10 km / h, the pump tilt angle of the working hydraulic pump 3 is controlled to be small, so that the working hydraulic pump 3 and the tank T2 are not connected. The flow rate of the hydraulic oil circulating in is reduced.

  As described above, the rough terrain crane according to the first embodiment includes the traveling hydraulic motor 17, the traveling hydraulic pump 4 for driving the traveling hydraulic motor 17, and the traveling hydraulic pump 4. Supplyed to the tank T <b> 1 in which the hydraulic fluid of the traveling hydraulic circuit for driving the motor 17 is returned, the hydraulic cylinder 6, the working hydraulic pump 3 for driving the hydraulic cylinder 6, and the working hydraulic pump 3. A tank T2 in which the hydraulic oil is stored. And the tank T1 and the tank T2 are arrange | positioned separately.

According to this configuration, the tank T1 in which high-temperature hydraulic fluid is returned from the traveling hydraulic circuit during traveling and the tank T2 in which hydraulic fluid to be supplied to the working hydraulic pump 3 are separated are separated from each other. While heat transfer from the 1 storage part to the 2nd storage part can be suppressed, since it is separated so that it may be insulatively insulated, the heat transfer can be further suppressed. Thereby, it can suppress that the hydraulic fluid supplied to the hydraulic cylinder 6 via the working hydraulic pump 3 becomes too high temperature.
That is, when crane operation is performed after traveling, low-temperature hydraulic oil with suppressed temperature rise can be supplied from the tank T2 to the boom expansion / contraction hydraulic cylinder 6. As a result, the hydraulic oil in the bottom chamber 6a of the hydraulic cylinder 6 is cooled, and the amount of contraction of the telescopic boom caused by the negative pressure generated in the bottom chamber 6a can be suppressed.

  Further, the hydraulic oil supplied to the traveling hydraulic circuit is stored in the tank T1, and the capacity of the tank T1 is smaller than the capacity of the tank T2.

  According to this configuration, the hydraulic oil is supplied from the tank T1 to the traveling hydraulic circuit that constitutes the HST system used during traveling and the other traveling system hydraulic system 50. Here, when the temperature of the hydraulic oil is higher to some extent, power loss such as pipe pressure loss can be reduced. According to the structure of 1st Embodiment, since the capacity | capacitance of tank T1 is small, the temperature of the hydraulic fluid in tank T1 can be raised rapidly at the time of driving | running | working. Thereby, piping pressure loss can be reduced and it becomes possible to improve driving | running | working fuel consumption.

  Further, the working hydraulic pump 3 is a variable displacement hydraulic pump, and when traveling at a speed exceeding a predetermined speed (10 km / h), the tilt angle of the working hydraulic pump 3 is set at a non-traveling time. The working hydraulic pump 3 is controlled to be smaller. The tilt angle of the working hydraulic pump 3 is controlled by a pump control means including a working pump regulator 5, a controller 7, an electromagnetic switching valve 8, a pilot pressure source 9, and a speed sensor 10. The

  According to this configuration, when traveling at a speed exceeding a predetermined speed (10 km / h), the discharge capacity from the working hydraulic pump 3 becomes smaller than when not traveling. Therefore, when traveling at a speed exceeding a predetermined speed (10 km / h), even if the working hydraulic pump 3 is driven together with the traveling hydraulic pump 4, the working oil circulating in the working hydraulic circuit and the tank T2 The flow rate can be reduced. Thereby, it can suppress that the temperature of the hydraulic fluid in a working hydraulic circuit and tank T2 rises.

  Further, the rough terrain crane according to the present embodiment is a hydraulic traveling working vehicle with a telescopic boom provided with an extendable boom that can be raised and lowered and a hydraulic cylinder 6 for extending and retracting the telescopic boom as a working hydraulic actuator. is there.

When the temperature of the hydraulic fluid supplied to the boom expansion / contraction hydraulic cylinder 6 is high, the hydraulic fluid is contracted due to a decrease in the temperature of the hydraulic fluid over time, so that the holding position by the hydraulic cylinder 6 is changed. May change. In particular, in a hydraulic traveling work vehicle with a telescopic boom, the oil temperature in the hydraulic cylinder for expanding and contracting the boom decreases, so that the balance due to the static friction force between the unit booms that are nested with each other is broken, and the hydraulic cylinder at once. Shrinks, a large impact sound is generated, and not only the telescopic mechanism but also the boom itself may be damaged.
In this respect, in the hydraulic traveling work vehicle with the telescopic boom according to the present embodiment, it is possible to suppress the hydraulic oil supplied to the hydraulic cylinder 6 via the working hydraulic pump 3 from becoming excessively high. Thereby, contraction of the hydraulic oil due to a decrease in the oil temperature can be suppressed, and a change in the holding position of the hydraulic cylinder 6 can be prevented. As a result, it is possible to suppress the generation of impact sound due to contraction of the hydraulic cylinder, and it is possible to prevent damage to the expansion / contraction mechanism and damage to the boom itself due to impact during contraction.

(Second Embodiment)
FIG. 2 is a hydraulic circuit configuration diagram of a rough terrain crane according to a second embodiment of the present invention.
The rough terrain crane according to the second embodiment is provided with (1) a first return oil passage 61 for returning the working oil of the working hydraulic circuit to the tank T1, and (2) the working oil of the working hydraulic circuit in the tank T2. The point from which the oil cooler is not provided in the 2nd return oil path 62 to return, and the point from which the communication oil path 63 which connects the tank T1 and the tank T2 is provided are different from 1st Embodiment. Other configurations are the same as those of the first embodiment. In FIG. 2, the same members as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The first return oil passage 61 is an oil passage extending between the relief valve 13 and the tank T1. In the first return oil passage 61, an oil passage 33 for discharging hydraulic oil in the hydraulic cylinder 6, a return oil passage 43 from the traveling hydraulic circuit, and a return oil passage 44 from another traveling hydraulic system 50. Is connected. In the first return oil passage 61, the oil cooler 23 and the hydraulic oil for cooling the hydraulic oil returning to the tank T 1 are located closer to the tank T 1 than the connection portion between the oil passage 33, the return oil passage 43, and the return oil passage 44. A filter 24 for removing impurities mixed in is interposed.

  The second return oil passage 62 is an oil passage provided between the switching valve 11 and the tank T2, and communicates with the oil passage 31 when the switching valve 11 is switched to the second position 11b. The second return oil passage 62 is provided with a filter 15 for removing impurities mixed in the hydraulic oil, but is not provided with an oil cooler.

  The communication oil path 63 is an oil path provided between the tank T1 and the tank T2. As schematically shown in FIG. 3, the communication oil passage 63 has a pipe having both ends connected to an opening edge provided on the side wall of the tank T1 and an opening edge provided on the side wall of the tank T2. Configured. The piping is arranged so that the position of the end on the tank T1 side is substantially the same as the position of the end on the tank T2 side. In addition, the opening of the tank side wall and the pipe end are provided at positions higher than the height of the oil level when a predetermined amount (150 L, 350 L) of hydraulic oil is stored in the tanks T1, T2, respectively. Thereby, when the oil level of the hydraulic oil in the tank T1 rises and exceeds the height of the pipe end, the hydraulic oil in the tank T1 is guided into the tank T2 via the pipe. .

  As described above, the rough terrain crane according to the second embodiment uses the first return oil passage 61 that returns the working oil of the working hydraulic circuit and the traveling hydraulic circuit to the tank T1, and the working oil of the working hydraulic circuit. A second return oil passage 62 for returning to the tank T2 and an oil cooler 23 that cools the working oil only in the first return oil passage 61 among the first return oil passage 61 and the second return oil passage 62 are provided. . Further, a communication oil path 63 is provided between the tank T1 and the tank T2 so that when the hydraulic oil is supplied to the tank T1 exceeding a predetermined amount, the hydraulic oil in the tank T1 is guided to the tank T2. .

According to this configuration, the hydraulic oil in the working hydraulic circuit and the traveling hydraulic circuit can be cooled by the oil cooler 23 provided in the first return oil passage 61 and returned to the tank T1. Thus, the hydraulic oil returning to the tank from the working hydraulic circuit and the traveling hydraulic circuit can be cooled without providing a plurality of oil coolers in the return oil path from the working hydraulic circuit and the traveling hydraulic circuit to the tank. it can. As a result, the installation space and installation cost of the oil cooler can be reduced.
When the hydraulic oil is supplied to the tank T1 beyond the predetermined amount, the hydraulic oil in the tank T1 is guided to the tank T2, so that the hydraulic oil is supplied beyond the shortage of the tank T2 or the capacity of the tank T1. Can be prevented.

In the second embodiment, when the switching valve 11 is switched to the second position 11b (when not in operation), the hydraulic oil supplied from the working hydraulic pump 3 passes through the second return oil passage 62. Return to the tank T2. On the other hand, when the switching valve 11 is switched to the first position 11a or the third position 11c (during operation), the valve returns to the tank T1 via the first return oil passage 61.
Thus, when not working, the hydraulic oil supplied from the working hydraulic pump 3 returns to the tank T2 through the oil passage with less pressure loss due to the absence of the oil cooler. It can be reduced. On the other hand, at the time of work, the hydraulic oil that has been used as power and whose temperature has risen passes through the oil cooler 23 and returns to the tank T1, so that the temperature rise of the hydraulic oil can be suppressed.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. For example, the following modifications can be made.

(1) The present invention can be applied not only to a rough terrain crane which is a kind of wheel crane, but also to other work vehicles. For example, the present invention can be applied to a crawler crane having a crawler as a traveling body driven by hydraulic pressure and a telescopic boom that is expanded and contracted by a hydraulic cylinder.

(2) In the above embodiment, the configuration including the two tanks T1 and T2 is shown. However, by separating the storage space inside one tank by the partition plate, two separated storage portions are formed. Also good. And by making the partition plate between two storage parts into a heat insulation structure, the heat transfer from one storage part to another storage part can be reduced, and the hydraulic fluid supplied to the working hydraulic actuator is excessive. It is possible to more reliably prevent the temperature from becoming too high. Moreover, in the structure which has this partition plate, the communicating oil path 63 shown in 2nd Embodiment can be comprised as a through-hole formed in the said partition plate. In this case, the communication oil passage can be realized with a simple configuration.

(3) In the above-described embodiment, as the working hydraulic actuator, the configuration including the hydraulic cylinder 6 for extending and retracting the telescopic boom provided to be raised and lowered is illustrated. The structure which drives the hydraulic cylinder etc. for raising and lowering a boom may be sufficient.

It is a hydraulic circuit block diagram of the rough terrain crane which concerns on 1st Embodiment of this invention. It is a hydraulic circuit block diagram of the rough terrain crane which concerns on 2nd Embodiment of this invention. It is a figure which shows typically the structure of the communicating oil path which connects tank T1, T2.

Explanation of symbols

3 Working hydraulic pump 4 Traveling hydraulic pump 5 Working pump regulator (pump control means)
6 Hydraulic cylinder (working hydraulic actuator)
7 Controller (pump control means)
8 Solenoid switching valve (pump control means)
9 Pilot pressure source (pump control means)
10 Speed sensor (pump control means)
17 Traveling hydraulic motor (traveling hydraulic actuator)
23 Oil cooler (cooling means)
61 1st return oil path 62 2nd return oil path 63 Communication oil path T1 tank (1st storage part)
T2 tank (second reservoir)

Claims (5)

A traveling hydraulic actuator;
A traveling hydraulic pump for driving the traveling hydraulic actuator;
A first reservoir that returns hydraulic oil of a traveling hydraulic circuit for driving the traveling hydraulic actuator by the traveling hydraulic pump;
A working hydraulic actuator;
A working hydraulic pump for driving the working hydraulic actuator;
A second reservoir that is formed separately from the first reservoir and stores hydraulic fluid supplied to the working hydraulic pump;
Work vehicle equipped with.   The first storage unit is a storage unit that stores hydraulic oil supplied to the traveling hydraulic circuit, and a capacity of the first storage unit is smaller than a capacity of the second storage unit. The work vehicle as described in.   The communication oil is provided between the first reservoir and the second reservoir so that the hydraulic oil that has overflowed from one of the first reservoir and the second reservoir is introduced into the other reservoir. The work vehicle according to claim 1 or 2, wherein a road is provided. A working hydraulic circuit for driving the working hydraulic actuator by the working hydraulic pump and a first return oil passage for returning the working hydraulic circuit hydraulic oil to the first reservoir;
A second return oil passage for returning the hydraulic oil of the working hydraulic circuit to the second reservoir,
4. The work vehicle according to claim 3, further comprising a cooling unit configured to cool the working oil only in the first return oil path among the first return oil path and the second return oil path. The first storage part and the second storage part are formed by partitioning a storage space inside one tank by a partition plate having a heat insulating structure,
The work vehicle according to claim 3 or 4, wherein the communication oil passage is a through hole formed in the partition plate.

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