JP2007051454A - Hydraulic oil cooling system for construction equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic oil cooling system for construction equipment which is economical, alleviates an excessive heat load imposed on an instrument of a hydraulic circuit, and contributes to the prevention of damage to the instrument to the possible extent. <P>SOLUTION: The hydraulic oil cooling system for the construction equipment is formed of hydraulic cylinders 21, 22, a hydraulic pump 20 for generating pressure oil for driving the hydraulic cylinders 21, 22, direction control valves 23, 24 for switching the flow and flow rate of the pressure oil from the hydraulic pump 20 to the hydraulic cylinders 21, 22, and an oil cooler 28 for cooling hydraulic oil, and functions to cool the hydraulic oil flowing in the hydraulic circuit by the oil cooler 28. Herein the hydraulic oil cooling system is further comprised of an oil cooler 29 across a feed pipe line a at a location between the hydraulic pump 20 and the direction control valve 23. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The invention of this application includes a hydraulic actuator, a hydraulic pump, a directional control valve that switches a flow and a flow rate of hydraulic fluid supplied from the hydraulic pump to the hydraulic actuator, and hydraulic fluid cooling means that cools the hydraulic fluid. The present invention relates to a hydraulic oil cooling system for a construction machine such as a hydraulic excavator or a crane that cools flowing hydraulic oil with hydraulic oil cooling means.

  Construction machines such as hydraulic excavators and cranes have a vehicle body that travels with a crawler and a wheel, and a work machine that is installed on the vehicle body and performs construction work such as excavation work and unloading work. Taking a hydraulic excavator as an example, the vehicle body can be broadly divided into a base for installing the upper revolving unit, a lower traveling unit capable of traveling on the work site, and a swivel mounted on the lower traveling unit. And an upper revolving body. Among these, the lower traveling body can be driven by driving a crawler by a traveling motor as a hydraulic actuator, and the upper swing body can be rotated by driving a turning device by a turning motor as a hydraulic actuator. .

  On the other hand, the work implement is provided on the upper swing body with work tools such as an arm, a boom, and a bucket that are rotationally driven in the vertical direction, and these work tools are driven by a hydraulic cylinder as a hydraulic actuator. Then, various work such as excavation work and loading work is performed. The construction machine includes a hydraulic circuit in order to drive the various hydraulic actuators as described above with hydraulic pressure. In addition to the hydraulic actuator described above, this hydraulic circuit includes a hydraulic oil tank that stores hydraulic oil, a hydraulic pump that draws hydraulic oil in the hydraulic oil tank and generates pressure oil to drive the hydraulic actuator, Various devices such as a directional control valve for switching the flow and flow rate of the pressure oil supplied from the hydraulic pump to the hydraulic actuator are provided.

  In construction machines, hydraulic fluid circulating in the hydraulic circuit rises violently due to friction with the hydraulic circuit during the circulation process. Therefore, hydraulic oil cooling means for cooling the hydraulic oil is attached to the hydraulic circuit of the construction machine, and the hydraulic oil flowing through the hydraulic circuit is cooled by the oil cooler. The present invention seeks to improve a hydraulic fluid cooling system for construction machinery provided with such hydraulic fluid cooling means.

  Therefore, in order to facilitate understanding of the technical contents of the present invention, which will be described in detail later, a schematic structure related to a crawler type hydraulic excavator, which is a typical example of a construction machine, and a conventional example related to a hydraulic oil cooling system for a construction machine The technical contents will be described with reference to FIGS. FIG. 5 is a perspective view showing an example of a structure of a hydraulic excavator provided with a conventional hydraulic oil cooling system, and FIG. 6 is a hydraulic circuit diagram schematically showing a hydraulic oil cooling system for a construction machine according to a conventional example.

  First, a general structure of a crawler type hydraulic excavator, which is a typical example of a construction machine in which a hydraulic oil cooling system is installed, will be outlined based on FIG.

  In the figure, reference numeral 1 denotes an upper swing body that is pivotably installed on a lower traveling body (not shown), 2 is a pivot bearing that supports the upper swing body 1 so as to be pivotable, and a pivot drive for driving the pivot bearing. A turning device that is provided with a drive mechanism such as a turning motor and a speed reducer and that turns the upper turning body 1 with respect to the lower traveling body, the rear end of which can turn (tilt) in the vertical direction to the front part of the upper turning body 1 The boom 4 is pivotally mounted on the arm 4, the arm 4 is pivotally mounted so that the rear end of the boom 3 can rotate (swing) in the vertical direction to the front end of the boom 3, and 5 is perpendicular to the front end of the arm 4. A bucket 3a that is pivotably mounted in a direction and is detachably mounted, a boom cylinder that is driven to expand and contract to rotate the boom 3, and an arm that is driven to expand and contract and rotate the arm 4 The cylinder 5a is expanded and contracted to rotate the bucket 5. A bucket cylinder 6 for driving is provided with a boom 3, an arm 4 and a bucket 5, a boom cylinder 3a, an arm cylinder 4a and a bucket cylinder 5a, and is a working machine for performing various construction work such as excavation work and loading work. .

  Although not shown, the crawler-type hydraulic excavator includes a lower traveling body that serves as a base for installing the upper revolving body 1 and travels on the work site by an endless chain-shaped crawler belt. The upper swing body 1 is installed on the lower traveling body so as to be swingable by the swing device 2. The upper swing body 1 includes a swing frame that forms the base of the upper swing body 1 and hydraulic drive / control devices and operations such as a valve unit 9, a hydraulic pump 10, and an engine 11, which will be described later, installed on the swing frame. An assembly composed of various devices such as the chamber 16 is designated. The hydraulic excavator is roughly divided into a lower traveling body and an upper swing body 1, and a work machine 6 installed on the upper swing body 1. As the hydraulic actuator, in addition to the boom cylinder 3a, the arm cylinder 4a, and the bucket cylinder 5a, a traveling motor for driving the crawler belt of the lower traveling body, a swing motor for driving the upper swing body 1 to rotate, etc. Various hydraulic actuators (not shown) are provided.

  7 is a hydraulic oil tank for storing hydraulic oil, 8 is a fuel tank of the engine 11, 9 is a flow of pressure oil supplied to the various hydraulic actuators such as the boom cylinder 3a, the arm cylinder 4a, and the bucket cylinder 5a. A directional control valve unit 10 having various directional control valves for controlling the movements of the hydraulic actuators by switching the flow rate and the flow rate 10 sucks the hydraulic oil in the hydraulic oil tank 7 and drives the various hydraulic actuators. A pump device comprising a variable displacement hydraulic pump that generates pressure oil and peripheral devices, 11 an engine for driving the hydraulic pump in the pump device 10, and 12 for cooling the hydraulic oil An oil cooler as a hydraulic oil cooling means, 13 is a radiator for cooling the engine coolant after cooling the engine 11, and 14 is an engine The cooling fan is driven by the engine 11 and generates an air flow for air-cooling the oil cooler 12, the radiator 13, etc., 15 is an intercooler for cooling the air taken in by the engine 11, and 16 is for operating the hydraulic excavator. It is a cab.

  The directional control valve unit 9 is formed so that the above-mentioned various directional control valves are unitized to form an integral valve block, and constitutes an assembly of these directional control valves. The oil cooler 12 is formed by a thin pipe, and the hydraulic oil is sent into the thin pipe and cooled by the cooling fan 14. Although not clearly shown in the figure, the upper-part turning body 1 includes a circulation pipe for returning the engine cooling water from the cooled part of the engine 11 to the radiator 13 and then returning it to the cooled part of the engine 11, and the circulation pipe. A cooling water pump for circulating the engine cooling water through the road is provided. In normal times, the engine cooling water cooled by the radiator 13 can be continuously sent to the engine 11 by the cooling water pump and circulated. I have to.

  Next, a conventional hydraulic oil cooling system for construction machines will be described with reference to FIG. FIG. 6 schematically shows a hydraulic circuit of an unspecified construction machine in order to easily explain the conventional hydraulic oil cooling system.

  In the figure, reference numeral 20 denotes a variable displacement hydraulic pump that sucks the hydraulic oil in the hydraulic oil tank 27 and generates pressure oil for driving the hydraulic cylinders 21 and 22 described later, and 21 is generated by the hydraulic pump 20. A first hydraulic cylinder as a hydraulic actuator driven by pressure oil, 22 is a second hydraulic cylinder as a hydraulic actuator driven by pressure oil generated by the hydraulic pump 20, and 23 is supplied to the first hydraulic cylinder 21. The first directional control valve 24 controls the movement of the hydraulic cylinder 21 by switching the flow and flow rate of the pressurized oil, and the hydraulic pressure 24 is switched by switching the flow and flow rate of the pressure oil supplied to the second hydraulic cylinder 22. A second directional control valve for controlling the movement of the cylinder 22, 25 an engine for driving the hydraulic pump 20, 26 a cooling fan driven by the engine 15, 2 Hydraulic oil tank with a built-in filter 27a, the 28 is an oil cooler, hydraulic oil cooling means for cooling the hydraulic oil.

  Here, the correspondence between the elements in FIG. 6 and the elements in FIG. 5 will be described. The hydraulic pump 20 in FIG. 6 corresponds to the variable displacement hydraulic pump in the pump device 10 in FIG. The hydraulic cylinders 21 and 22 correspond to any two hydraulic cylinders of the boom cylinder 3a, the arm cylinder 4a, and the bucket cylinder 5a, and the directional control valves 23 and 24 are directional control valves in the directional control valve unit 9. It corresponds. Further, the engine 25, the cooling fan 26, the hydraulic oil tank 27, and the oil cooler 28 in FIG. 6 correspond to the engine 11, the cooling fan 14, the hydraulic oil tank 7, and the oil cooler 12 in FIG. Each element in FIG. 6 performs the same function as each corresponding element in FIG.

  The directional control valves 23 and 24 supply pressure oil from the hydraulic pump 20 to the rod sides of the hydraulic cylinders 21 and 22 as well as pressures at the bottoms thereof when switched to the left position by operating the operating means. The oil is discharged to the hydraulic oil tank 27, whereby the hydraulic cylinders 21 and 22 can be reduced. When switched to the right position, the pressure oil of the hydraulic pump 20 is supplied to the bottom sides of the hydraulic cylinders 21 and 22, and the pressure oil on the rod side is discharged to the hydraulic oil tank 27. Each hydraulic cylinder 21, 22 can be extended. In that case, the opening amount is adjusted in accordance with the operation amount of the operation means, whereby the speed at which the hydraulic cylinders 21 and 22 expand and contract can be controlled.

  In FIG. 6, for convenience, the hydraulic cylinders 21 and 22 are illustrated as the hydraulic actuators. However, the hydraulic actuators are not necessarily the same as the hydraulic cylinders 21 and 22, A hydraulic motor such as a swing motor may be used. Although not shown, a radiator such as the radiator 13 is disposed between the cooling fan 26 and the oil cooler 28 so that the engine cooling water can be air-cooled by the cooling fan 26.

In such a conventional hydraulic oil cooling system for construction machinery, it is natural that the oil cooler 28 is disposed in the return line b in the hydraulic circuit as shown in FIG. The reason is as follows. The hydraulic pressure in the main line for supplying and discharging the pressure oil to and from the hydraulic cylinders 21 and 22 is very high, unlike the hydraulic pressure such as the hydraulic pilot pressure in the pilot line. hydraulic pressure in the supply conduit a to supply the pressure oil of the hydraulic pump 20 to the directional control valve 23 and 24, for example, very high and ^{300kg / cm 2 ~350kg / cm 2} . On the other hand, the hydraulic pressure in the return pipe b for returning the pressure oil that has passed through the directional control valves 23 and 24 to the hydraulic oil tank 27 is, for example, less than 30 kg / cm ² and is considerably high. Compared to the hydraulic pressure in the pipe a, it is extremely low, 1/10 or less of the hydraulic pressure. For this reason, when the oil cooler 28 is arranged in the hydraulic circuit, the strength of the pipe of the oil cooler 28 is lower when the oil cooler 28 is arranged in the return pipe b than in the supply pipe a (the thickness of the pipe is reduced). As a result, the oil cooler 28 can be manufactured at low cost.

Further, by arranging the oil cooler 28 in the pressure oil return pipe b in this way, the wall thickness of the pipe of the oil cooler 28 can be reduced, so that heat transfer is also improved and the oil cooler 28 has an internal structure. The hydraulic oil can be air-cooled, and the same cooling fan 26 can cool the hydraulic oil together with the engine coolant in the radiator. For this reason, in the conventional hydraulic oil cooling system for construction machinery, the oil cooler 28 is arranged in the return line b in the hydraulic circuit, and the hydraulic oil is returned to the hydraulic oil tank 27 as a target to supply the hydraulic oil to the oil cooler. It was made to cool by 28. A hydraulic oil cooling system for a construction machine in which the oil cooler 28 is arranged in the return pipe b in this manner is disclosed in, for example, Patent Document 1.
CD-ROM (No. 4-10, Fig. 1-4) of Japanese Utility Model No. 4-33202 (Japanese Utility Model Publication No. 5-67655)

  Such a conventional hydraulic oil cooling system for construction machinery has the above-mentioned advantages, but on the hydraulic path from the hydraulic pump 20 to the hydraulic cylinders 21, 22, that is, the parts provided in the hydraulic path on the discharge side of the hydraulic pump 20. The problem of deterioration and damage occurred. For example, the service life of a hose partially provided in such a hydraulic path is reduced, the O-ring of the connecting portion of the hose and the pipe, the O-ring in the direction control valves 23 and 24, and the hydraulic cylinders 21 and 22 There was a lot of trouble that the oil seal was damaged. As a result of investigating the cause, it was found that these parts were subjected to an excessive heat load from the hydraulic oil, and deteriorated and damaged by the heat due to the excessive heat load.

  The result of the investigation on the cause will be described. The hydraulic oil on the return line b side cooled by the oil cooler 28 is once returned to the hydraulic oil tank 27 and then pressurized by the hydraulic pump 20. The hydraulic oil becomes hot due to pressurization by the hydraulic pump 20. This high-temperature hydraulic oil passes through the ports of the directional control valves 23 and 24 and is supplied to the hydraulic cylinders 21 and 22, and in particular, a large amount due to frictional resistance when passing through the ports of the directional control valves 23 and 24. The high-temperature hydraulic fluid that generates heat and is discharged from the hydraulic pump 20 becomes extremely hot. As a result, it has been found that parts provided in the hydraulic path on the discharge side of the hydraulic pump 20, particularly hoses and seals after the direction control valves 23 and 24, are deteriorated and damaged due to excessive heat load from the hydraulic oil. did.

  On the other hand, in the conventional hydraulic oil cooling system for construction machinery, in order to prevent such a problem, it is difficult to increase the cooling capacity of the oil cooler 28 with respect to the hydraulic oil on the suction side of the hydraulic pump 20. Referring to this point, the hydraulic oil that has become extremely hot at the locations of the directional control valves 23 and 24 is gradually radiated in the course of flowing through the hydraulic circuit and sent to the oil cooler 28 on the return line b. Therefore, the temperature difference between the hydraulic oil and the outside air is considerably smaller in the vicinity of the oil cooler 28 than on the discharge side of the hydraulic pump 20. Therefore, the cooling efficiency for cooling the hydraulic oil in the oil cooler 28 with the outside air by the cooling fan 26 is poor, and if the cooling capacity of the oil cooler 28 is to be increased, the oil cooler 28 needs to be significantly enlarged. Therefore, the hydraulic oil cooling system cannot be manufactured economically.

  The invention of this application was created in order to solve such problems of the prior art, and the technical problem was to reduce the excessive heat load received by the equipment of the hydraulic circuit and damage the equipment. It is an object of the present invention to provide an economical hydraulic fluid cooling system for construction machinery that prevents as much as possible.

  In order to achieve such a technical problem, the first invention of this application employs the following means 1), and the second invention of this application employs the following 2) means.

1) The hydraulic actuator, a hydraulic pump that generates hydraulic oil for sucking the hydraulic oil in the hydraulic oil tank and driving the hydraulic actuator, and the flow and flow rate of the hydraulic oil supplied from the hydraulic pump to the hydraulic actuator In a hydraulic fluid cooling system for a construction machine that includes a directional control valve for switching and hydraulic fluid cooling means for cooling the hydraulic fluid, and that cools hydraulic fluid flowing through the hydraulic circuit by the hydraulic fluid cooling means, the hydraulic fluid cooling means is a hydraulic pump Provided in the hydraulic circuit between the directional control valve.

2) The hydraulic actuator, the hydraulic pump that generates hydraulic oil for sucking the hydraulic oil in the hydraulic oil tank and driving the hydraulic actuator, and the flow and flow rate of the hydraulic oil supplied from the hydraulic pump to the hydraulic actuator In order to cool hydraulic fluid with water in a hydraulic fluid cooling system for a construction machine that includes a directional control valve for switching and hydraulic fluid cooling means for cooling hydraulic fluid, and that cools hydraulic fluid flowing through a hydraulic circuit by hydraulic fluid cooling means The water cooling type hydraulic oil cooling means is provided integrally with the hydraulic pump.

  As described above, the high-temperature hydraulic oil discharged from the hydraulic pump generates a large amount of heat due to frictional resistance when passing through the port of the directional control valve when it is supplied to the hydraulic actuator, and becomes extremely hot. In the hydraulic oil cooling system for a construction machine according to the first invention of this application that employs the means 1), the hydraulic oil cooling means is provided in the hydraulic circuit between the hydraulic pump and the directional control valve. The hydraulic oil that has become hot due to pressurization by the hydraulic pump is directly cooled by the hydraulic oil cooling means. For this reason, in particular, the high-temperature hydraulic oil is not sent to the directional control valve that generates a large amount of heat, and the low-temperature hydraulic oil cooled by the hydraulic oil cooling means is not sent. Will be. Therefore, although the hydraulic oil generates a considerable amount of heat when passing through the directional control valve, it does not become extremely hot, and the hydraulic oil such as an O-ring in the directional control valve as in the conventional art is not used. The parts on the discharge side are not deteriorated or damaged by receiving an excessive heat load from the hydraulic oil.

  On the other hand, in the hydraulic fluid cooling system of this construction machine, hydraulic fluid cooling means for preventing the occurrence of such an excessive heat load is disposed particularly on the discharge side of the hydraulic pump, so that the temperature of the hydraulic fluid and the outside air can be reduced. In the conventional hydraulic oil cooling system in which the hydraulic oil cooling means is arranged on the suction side of the hydraulic pump with a small difference, the hydraulic oil cooling means becomes excessively large, unlike when the cooling capacity of the hydraulic oil cooling means is increased. There is no such thing. Therefore, according to the present invention, there is obtained an economical hydraulic fluid cooling system for construction equipment capable of preventing parts on the discharge side of the hydraulic pump from being deteriorated and damaged by receiving an excessive heat load from the hydraulic fluid. be able to.

  In the hydraulic oil cooling system for a construction machine according to the second invention of this application that adopts the means of 2), the water-cooled hydraulic oil cooling means is provided integrally with the hydraulic pump. As with the hydraulic oil cooling system of the invention, high-temperature hydraulic oil from the hydraulic pump is not sent to the directional control valve, but hydraulic oil cooled by hydraulic oil cooling means integrated with the hydraulic pump is sent. . In addition, since the hydraulic oil cooling means is provided integrally with the hydraulic pump and is water-cooled, the hydraulic oil cooling means is different from the conventional case where the cooling capacity of the oil cooler is enhanced by the conventional hydraulic oil cooling system. There is no such thing as oversizing. Therefore, according to the present invention, it is possible to obtain an economical hydraulic fluid cooling system for construction machinery that can prevent the components on the discharge side of the hydraulic pump from being deteriorated and damaged by receiving an excessive heat load from the hydraulic fluid.

  As will be apparent from the following description, the first invention and the second invention of this application are the means 1) and 2) shown in the section of [Means for Solving the Problems], respectively. Therefore, in any of the inventions, an economical construction machine that can prevent the parts on the discharge side of the hydraulic pump from being deteriorated or damaged by excessive heat load from the hydraulic oil. The hydraulic fluid cooling system can be obtained. As a result, the reliability of the hydraulic circuit can be improved as compared with the conventional art.

  In particular, in the hydraulic fluid cooling system for a construction machine according to the second invention of this application, since the water-cooled hydraulic fluid cooling means is provided integrally with the hydraulic pump, the hydraulic fluid cooling means is the hydraulic pump and the direction control valve. No extra parts such as a connecting part between the hydraulic circuit and the hydraulic oil cooling means, which are required when the hydraulic circuit is provided between the hydraulic circuit and the hydraulic oil cooling unit, are required. Therefore, there is no possibility that troubles such as deterioration and damage of components such as connection components due to heat load occur, and the reliability of the hydraulic circuit can be further improved. Further, since the water-cooled hydraulic oil cooling means is provided integrally with the hydraulic pump as described above, the water-cooled hydraulic oil cooling means can also be used as a means for cooling the lubricating oil for lubricating the hydraulic pump.

  In order to carry out each invention of this application by explaining how the first invention and the second invention of this application are actually embodied with reference to FIGS. The desired form of is clarified.

  FIG. 1 is a hydraulic circuit diagram schematically showing a hydraulic oil cooling system for a construction machine configured by embodying the first invention of this application, and FIG. 2 embodying the second invention of this application. FIG. 3 is an enlarged perspective view of a main part of FIG. 2, and FIG. 4 is an enlarged cross-sectional view of the main part of FIG. In these drawings, the portions denoted by the same reference numerals as those in FIGS. 5 and 6 represent the same portions as those in FIGS.

  The hydraulic oil cooling system for each construction machine that is configured by embodying the first invention and the second invention of this application described below, respectively, is the hydraulic oil cooling system for a construction machine according to the conventional example described above. Similarly to the hydraulic cylinders 21 and 22 as hydraulic actuators, a variable displacement hydraulic pump 20 that draws hydraulic oil in the hydraulic oil tank 27 and generates pressure oil for driving the hydraulic cylinders 21 and 22; The hydraulic pump 20 includes directional control valves 23 and 24 for switching the flow and flow rate of pressure oil supplied from the hydraulic pump 20 to the hydraulic cylinders 21 and 22 and an oil cooler as hydraulic oil cooling means for cooling the hydraulic oil. It is for cooling the flowing hydraulic oil with an oil cooler. A radiator (not shown) such as the radiator 13 is provided between the cooling fan 26 and the oil cooler 28 so that the engine cooling water can be air-cooled by the cooling fan 26 as in the hydraulic oil cooling system of FIG. It is arranged.

  Therefore, based on FIG. 1, the characteristic technical contents of the hydraulic oil cooling system for a construction machine constructed by embodying the first invention of this application will be described.

  The greatest characteristic of the hydraulic oil cooling system for this construction machine is that an oil cooler 29 as hydraulic oil cooling means is provided in a supply line a which is a hydraulic circuit between the hydraulic pump 20 and the directional control valves 23 and 24. In the example shown in FIG. 1, an air-cooled type oil cooler 29 is provided. In this case, the return pipe b may be provided with an oil cooler 28 as in the conventional example, or may not be provided, and it can be selected as appropriate in design. In the example shown in FIG. 1, an example in which an oil cooler 28 as in the conventional example is provided in the return pipe b is shown, but even when such an oil cooler 28 is provided, the cooling capacity thereof is higher than that in the oil cooler 28 in the conventional example. Can also be reduced.

  The effects of the hydraulic oil cooling system for the construction machine adopting such means will be described.

  As already described in the section “Problems to be Solved by the Invention”, the hydraulic oil that has become hot due to pressurization by the hydraulic pump 20 passes through the directional control valves 23, 24 to the hydraulic cylinders 21, 22. Although supplied, this high-temperature hydraulic oil generates a large amount of heat and becomes extremely hot due to the frictional resistance particularly when passing through the ports of the direction control valves 23 and 24. In the hydraulic oil cooling system of the present construction machine, the oil cooler 29 is provided in the supply pipe line a which is a hydraulic circuit between the hydraulic pump 20 and the direction control valves 23, 24. The hydraulic oil that has reached a high temperature is directly cooled by the oil cooler 29.

  Therefore, in particular, the high-temperature hydraulic oil is not sent to the directional control valves 23 and 24 where the hydraulic oil generates a large amount of heat, and the hydraulic oil cooled by the oil cooler 29 is low. Will be sent. As a result, the hydraulic oil generates a considerable amount of heat when passing through the direction control valves 23 and 24, but does not reach an extremely high temperature as in the prior art. Components on the discharge side of the hydraulic pump 20 such as the beginning are not deteriorated or damaged by receiving an excessive heat load from the hydraulic oil.

  On the other hand, in the hydraulic oil cooling system of the construction machine, the oil cooler 29 for preventing the occurrence of such an excessive heat load is disposed particularly on the discharge side of the hydraulic pump 20, so that the temperature of the hydraulic oil and the outside air is reduced. In the conventional hydraulic oil cooling system in which the oil cooler 29 is arranged on the suction side of the hydraulic pump 20 with little difference, unlike the case where the cooling capacity of the oil cooler 28 is increased, the oil cooler 29 is excessively enlarged. There is nothing. Therefore, the hydraulic oil cooling system of the construction machine can prevent the parts on the discharge side of the hydraulic pump 20 from being deteriorated or damaged by receiving an excessive heat load from the hydraulic oil, and can be manufactured economically. can do. As a result, the reliability of the hydraulic circuit can be improved as compared with the conventional art.

  Based on FIG. 2 thru | or FIG. 4, the technical content characteristic about the hydraulic fluid cooling system of the construction machine which actualized and comprised the 2nd invention of this application is demonstrated.

  The greatest characteristic of the hydraulic oil cooling system for this construction machine is that a water-cooled hydraulic oil cooling means for cooling the hydraulic oil with water is provided integrally with the hydraulic pump 20. 2 to 4, reference numeral 30 denotes a pump oil cooler which is an example of a device in which hydraulic oil cooling means is provided integrally with a hydraulic pump. Based on FIG.3 and FIG.4, the concrete structure of this pump oil cooler 30 and the matter of the periphery are demonstrated below.

  In these drawings, 20 is a variable displacement hydraulic pump, and 31 is a hydraulic oil cooling passage specially provided in the pump oil cooler 30 for cooling the hydraulic oil discharged from the hydraulic pump 20. , 32 is also provided in the pump oil cooler 30 and is branched from the oil passage 31 for cooling the hydraulic oil, and 33 is a branch oil passage for cooling the hydraulic oil, and 33 is the hydraulic oil flowing through the oil passage 31 and the branched oil passage 32. The hydraulic oil discharge port for guiding the pump oil cooler 30 to the outside, 34 is a cooling water suction port for guiding the cooling water into the pump oil cooler 30, and 35 cools the hydraulic pump 20, the oil passage 31 and the branch oil passage 32. A cooling water channel 36 for circulating cooling water for the purpose of cooling, a cooling water discharge port 36 for guiding the cooling water flowing through the cooling water channel 35 to the outside of the pump oil cooler 30, and a cooling water port 37 provided in the cooling water discharge port 36. It closed when the temperature of the water falls below a predetermined temperature, or an opening amount reduces serve to reduce the discharge amount of the cooling water thermostat (a type of valve).

  The branch oil passage 32 for cooling the hydraulic oil is provided with a plurality of openings 32a communicating with the oil passage 31 for cooling the hydraulic oil, and is connected in parallel to each other. The total area of the openings 32a of the plurality of branch oil passages 32 is made larger than the area of the flow passage of the oil passage 31 for cooling the hydraulic oil. When the hydraulic oil cooling means is provided on the discharge side of the hydraulic pump 20, pressure loss is generated in the pressure oil supplied to the actuator. Thus, a plurality of hydraulic oil cooling channels 31 are provided in the hydraulic oil cooling passage 31. By connecting the branch oil passage 32, the area of the flow path on the downstream side of the oil path 31 for cooling the hydraulic oil can be made larger than the area of the flow path of the oil passage 31, so that such pressure loss occurs. Can be prevented as much as possible.

  As shown in FIG. 4, the cooling water passage 35 is disposed in various places so as to cover the periphery of the hydraulic pump 20 and the oil passage 31 and the branch oil passage 32 to form a water-cooled water jacket. The water jacket has a pressure-resistant structure because it is disposed at a location where the discharge oil of the high-pressure hydraulic pump 20 flows. Although not clearly shown in the figure, the cooling water passage 35 arranged in various places in the pump oil cooler 30 is arranged such that the cooling water sucked from the cooling water suction port 34 reaches the cooling water passage 35 at any location. The cooling water flowing through the cooling water passage 35 at any location is formed so as to be guided to the cooling water discharge port 36. The cooling water suction port 34 is supplied with engine cooling water cooled by the radiator 13 of the engine 11 or cooling water of a dedicated radiator (not shown) separately installed. It returns to such a radiator from the outlet 36 to be circulated.

  When the cooling water used for the pump oil cooler 30 is engine cooling water, when the construction machine is operated in an extremely cold environment, the relatively warm engine cooling water is guided to the cooling water passage 35 and used as a radiator. As a result, it is possible to warm up the high-viscosity hydraulic oil in an extremely cold environment and subsidize the warm-up operation, thereby speeding up the start of the normal operation. The thermostat 37 is normally fully opened, and when the temperature of the cooling water drops more than necessary, the cooling water discharge port 36 is closed or squeezed to prevent overcooling of the hydraulic oil. By providing such a thermostat 37 at the cooling water discharge port 36, for example, the cooling water discharge port 36 is throttled during idling operation of the construction machine to prevent the hydraulic oil from being increased in viscosity due to overcooling of the hydraulic oil. The directional control valves 23, 24, etc. due to the increase in oil viscosity are prevented from being shortened or damaged.

  When the pump oil cooler 30 as described above is provided, the oil cooler 28 may or may not be provided in the return line b as in the example of FIG. You can choose. Further, when the pump oil cooler 30 is provided, the cooling capacity of the oil cooler 28 can be reduced as compared with the conventional one. In FIG. 3, reference numeral 38 denotes a pilot pump attached to the pump oil cooler 30 for generating a hydraulic pilot pressure for controlling the directional control valves 23, 24, etc., and 39 is an engine 11 for driving the hydraulic pump 20. Is an engine attachment portion to which is attached. In the example of FIG. 3, the cooling means for cooling the pilot oil of the pilot pump 38 is not installed, and even if the cooling means is installed, the hydraulic pilot pressure is considerably lower than the hydraulic oil pressure. Therefore, unlike the hydraulic oil cooling means, there are no restrictions on installation.

  The effects of the hydraulic oil cooling system for the construction machine provided with the pump oil cooler 30 as described above will be described.

  In the hydraulic oil cooling system of this construction machine, since the pump oil cooler 30 having a structure integrated with the hydraulic pump 20 is installed, the high-temperature operation from the hydraulic pump 20 is performed as in the hydraulic oil cooling system of FIG. The oil is not sent to the direction control valves 23 and 24, and the hydraulic oil cooled by the water jacket type cooling water passage 35 as hydraulic oil cooling means integrated with the hydraulic pump 20 is sent. Further, since the hydraulic oil cooling means is provided integrally with the hydraulic pump 20 and is water-cooled, the hydraulic oil cooling means is different from the case where the cooling capacity of the oil cooler 28 is enhanced by a conventional hydraulic oil cooling system. However, it does not become excessively large as in the past. Therefore, the hydraulic oil cooling system of the construction machine also prevents the parts on the discharge side of the hydraulic pump 20 from being deteriorated or damaged due to an excessive heat load from the hydraulic oil, like the hydraulic oil cooling system of FIG. Can be produced economically.

  When the oil cooler 29 as the hydraulic oil cooling means is provided in the supply pipeline a as in the hydraulic fluid cooling system of FIG. 1 described above, the connecting parts of the supply pipeline a and the oil cooler 29, etc. Since extra parts are required, troubles such as deterioration and damage of parts such as connecting parts due to heat load may occur, or it may be necessary to take preventive measures against such troubles. On the other hand, in the hydraulic oil cooling system of this construction machine, the hydraulic oil cooling means is provided integrally with the hydraulic pump 20 by the pump oil cooler 30. There is no fear of occurrence, and the reliability of the hydraulic circuit can be further improved.

  By the way, in the casing of the hydraulic pump 20, hydraulic oil is sucked from the hydraulic oil tank 7 as a lubricating oil for lubricating the hydraulic pump, lubricates the inside, and then returned to the hydraulic oil tank 7 and circulates. The hydraulic oil tank 7 lubricated by the hydraulic pump 20 and returned to the hydraulic oil tank 7 is heated by the hydraulic pump 20 and has a considerably high temperature. Therefore, when the circulation of the hydraulic oil is repeated, The temperature of the hydraulic oil rises significantly. In the hydraulic oil cooling system of the present construction machine, in particular, since the water jacket type cooling water channel 35 as the hydraulic oil cooling means is provided integrally with the hydraulic pump 20, the water jacket type cooling water channel 35 is used for lubricating the hydraulic pump. It can also be used as a means for cooling the lubricating oil.

1 is a hydraulic circuit diagram schematically showing a hydraulic oil cooling system for a construction machine configured by embodying the first invention of this application. FIG. It is a perspective view which shows the hydraulic shovel which installed the hydraulic fluid cooling system of the construction machine which actualized and comprised the 2nd invention of this application. It is an expansion perspective view of the principal part of FIG. It is an expanded sectional view of the principal part of FIG. FIG. 5 is a perspective view showing an example of a structure of a hydraulic excavator provided with a conventional hydraulic oil cooling system. It is a hydraulic circuit diagram which shows typically the hydraulic fluid cooling system of the construction machine of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper revolving body 3 Boom 3a Boom cylinder 4 Arm 4a Arm cylinder 5 Bucket 5a Bucket cylinder 6 Working machine 7 Hydraulic oil tank 9 Directional control valve unit 10 Pump apparatus 11 Engine 12 Oil cooler 13 Radiator 14 Cooling fan 20 Variable capacity hydraulic pressure Pumps 21, 22 Hydraulic cylinders 23, 24 Directional control valve 25 Engine 26 Cooling fan 27 Hydraulic oil tank 28 Oil cooler 29 Oil cooler 30 Pump oil cooler 31 Oil path for cooling hydraulic oil 32 Branch oil path for cooling hydraulic oil 33 Operation Oil outlet 34 Cooling water inlet 35 Cooling water channel 36 Cooling water outlet 37 Thermostat

Claims (2)

  A hydraulic actuator, a hydraulic pump that generates hydraulic oil for sucking the hydraulic oil in the hydraulic oil tank and driving the hydraulic actuator, and a direction for switching the flow and flow rate of the hydraulic oil supplied from the hydraulic pump to the hydraulic actuator In a hydraulic fluid cooling system for a construction machine that includes a control valve and hydraulic fluid cooling means that cools hydraulic fluid, and that cools hydraulic fluid flowing in a hydraulic circuit by hydraulic fluid cooling means, the hydraulic fluid cooling means and the hydraulic pump and direction control A hydraulic oil cooling system for a construction machine, which is provided in a hydraulic circuit between the valve and the valve. A hydraulic actuator, a hydraulic pump that generates hydraulic oil for sucking the hydraulic oil in the hydraulic oil tank and driving the hydraulic actuator, and a direction for switching the flow and flow rate of the hydraulic oil supplied from the hydraulic pump to the hydraulic actuator A water cooling system for cooling hydraulic oil with water in a hydraulic oil cooling system for a construction machine that includes a control valve and hydraulic oil cooling means for cooling the hydraulic oil, and that cools the hydraulic oil flowing through the hydraulic circuit by the hydraulic oil cooling means. A hydraulic fluid cooling system for construction machinery, wherein a hydraulic fluid cooling means of the type is provided integrally with a hydraulic pump.

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