JP5997684B2 - Construction machine equipped with preheating unit and preheating method thereof - Google Patents

Description

  The present invention relates to a construction machine including a preheating unit for preheating a fluid such as cooling water, mission oil, hydraulic oil, etc. of a prime mover (engine or electric motor) and a preheating method thereof.

  In construction machines such as hydraulic excavators, various fluids (liquids) such as cooling water of a prime mover (engine or electric motor), lubricating oil (transmission oil) of a transmission, and operating oil of an actuator are used. When such a construction machine is used in an extremely cold region of, for example, −40 ° C. or less, once the prime mover is stopped, those fluids may freeze and it may be difficult to restart. Further, if the prime mover is started in a state where the lubricating oil such as mission oil is frozen and its lubricating performance is lost, the transmission, the hydraulic pump, the actuator, etc. may be damaged.

  As a technique for improving engine startability in cold weather, for example, in Patent Document 1 below, a heater is provided in a suction line connecting a hydraulic pump and a hydraulic oil tank, and the operation in the suction line is performed before the engine is started. Techniques have been proposed for improving engine startability by warming up the oil. Patent Document 2 below proposes a technique in which a preheater is provided in an engine, a cab, etc., and the engine, the cab, etc. are preheated by the preheater. Further, Patent Document 3 below proposes a technique for warming the hydraulic oil of the entire vehicle body by driving both a main electric motor and an electric heater that drive the vehicle body.

JP-A-8-284907 JP 2000-80679 A Japanese Patent No. 5271500

  Incidentally, the conventional preheating method as described above has the following disadvantages. That is, in the technique shown in Patent Document 1, since the working oil to be warmed is limited to the local area of the suction pipe only, it is difficult to sufficiently preheat in an extremely cold region of −40 ° C. or lower. In particular, an electric hydraulic excavator is provided with a transmission for amplifying the pump rotation speed at a location where a main electric motor and a pump are connected.

  This transmission employs a forced circulation system using a pump operated by the electric motor, and includes a plurality of narrow tubes for supplying lubricating oil directly to bearings and gears. For this reason, if the viscosity of the mission oil becomes high or freezes inside the narrow tube and the supply is insufficient or stopped, there is a risk of local lubrication failure and the bearings and gears may be seized and damaged. Therefore, it is necessary to sufficiently preheat not only the hydraulic oil suction pipe but also this transmission.

  On the other hand, the technique shown in Patent Document 2 is a system in which engine cooling water is heated by a combustion heater, and therefore, in an area where the altitude is higher than 2000 m above sea level, the oxygen concentration is low and good combustion is achieved. Is difficult. Furthermore, the technique as shown in Patent Document 3 has a sufficient heating function, but has a disadvantage that it does not function when the main electric motor is stopped due to maintenance or the like.

  Therefore, the present invention has been devised to solve these problems, and an object of the present invention is to provide a construction machine including a novel preheating unit capable of efficiently preheating the entire circulation path through which the fluid flows, and a method for preheating the construction machine. Is to provide.

  In order to solve the above-mentioned problems, the first invention is a construction machine characterized in that a bypass path is provided in a circulation path for circulating a fluid, and the bypass path includes a preheating unit including a heater and a bypass pump. It is. According to such a configuration, even when the circulation of the fluid in the circulation path is stopped, the fluid can be heated while circulating the fluid through the bypass path, so that the entire circulation path can be efficiently preheated. Can do. Moreover, since it can be retrofitted to an existing circuit, excellent versatility can be exhibited.

  According to a second invention, in the first invention, the bypass path is provided between an upstream side and a downstream side of a circulation pump provided in the circulation path, and the bypass pump of the preheating unit is a pump of the circulation path. It is a construction machine characterized by circulating fluid in the same direction. According to such a configuration, even when the circulation pump is stopped, the fluid can be heated while reliably circulating the fluid in the same direction as the pump of the circulation path, so that the entire circulation path is efficiently preheated. be able to.

  According to a third invention, in the first invention, the circulation path circulates lubricating oil between the hydraulic oil tank and the main pump, and the bypass path is provided between the hydraulic oil tank and the main pump. A construction machine is provided in parallel with a circulation path, and a circulation loop of hydraulic oil is formed by the circulation path and the bypass path. According to such a configuration, the small-loop circulation path can be formed by the bypass path in the large-loop circulation path formed between the hydraulic oil tank and the main pump, so that the main pump is in a stopped state. Even with a small amount of heat, the hydraulic oil in the hydraulic oil tank can be circulated while preheating through the bypass.

  A fourth invention is the construction machine according to the first or second invention, wherein the circulation path is a circulation path for circulating transmission mission oil. According to such a configuration, even if the transmission and its circulation pump are stopped, the transmission oil can be heated while being reliably circulated in the circulation path, so that the entire transmission can be efficiently preheated. .

  A fifth invention is a construction machine according to any one of the first to third inventions, wherein the circulation path is a circulation path for circulating cooling water for a prime mover. According to such a configuration, even when a prime mover such as an engine (internal combustion engine) or an electric motor and its circulation pump are stopped, the engine can be heated while reliably circulating cooling water in the circulation path. The whole can be efficiently preheated.

  A sixth invention is the construction machine according to the third invention, wherein the bypass path connects between the hydraulic oil tank and the suction tank. According to such a configuration, even when the circulation of the hydraulic oil in the hydraulic oil tank is stopped, the whole is efficiently preheated while reliably circulating the hydraulic oil between the hydraulic oil tank and the suction tank. can do.

  7th invention is the preheating method regarding 1st thru | or 6th invention, Comprising: The outside temperature when the prime mover has stopped, and the said fluid temperature are measured, The said outside temperature is less than 1st predetermined value T1 When the fluid temperature is less than a second predetermined value T2 (where T1 <T2), the fluid heating by the heater of the preheating unit and the fluid circulation by the bypass pump are performed, and the outside air temperature is the first temperature. When the fluid temperature is lower than the predetermined value T1 and the fluid temperature is equal to or higher than the second predetermined value T2, only the fluid circulation by the bypass pump of the preheating unit is performed. According to such a preheating method, the fluid (oil type) can be heated only when preheating is necessary, so that effective preheating without waste can be performed.

  In the present invention, even when the engine is stopped and the circulation of the fluid such as the mission oil is stopped in the circulation circuit of the transmission or the like, the fluid can be heated while circulating the fluid through the bypass path. It can be preheated efficiently. Moreover, since it has the structure which branched the bypass path with respect to the existing circulation path and attached the preheating unit to the bypass path, it can be easily attached to an existing construction machine by retrofitting. Furthermore, since the fluid circulation and heating by the preheating unit are finely controlled in accordance with changes in the outside air temperature, oil temperature, and the like while the engine is stopped, efficient preheat treatment can be performed while suppressing wasteful power consumption.

1 is a longitudinal sectional view showing an embodiment of a construction machine (hydraulic excavator) 100 according to the present invention. 1 is a schematic diagram showing a configuration near a power train of a construction machine (hydraulic excavator) 100. FIG. FIG. 4 is a schematic diagram showing a configuration of a circulation path 60A of a transmission 60. It is a follow chart figure which shows the flow of the preheating control using the preheating unit 67 which concerns on this invention. It is a schematic diagram which shows the structure of the powertrain vicinity of the conventional construction machine (hydraulic excavator).

  Next, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows an embodiment of a hydraulic excavator 100 which is one of the construction machines according to the present invention. As shown in the figure, the excavator 100 is mainly composed of a lower traveling body 10 and an upper revolving body 20 provided on the lower traveling body 10 so as to be rotatable. The lower traveling body 10 has a pair of crawlers 11 positioned parallel to each other on a traveling body frame (not shown). The crawlers 11 are hydraulically driven traveling motors for traveling by driving the respective crawler belts. 12 is provided.

  On the other hand, the upper swing body 20 includes an engine room 22 installed on the swing body frame 40, a cab 23 provided on the front left side of the engine room 22, and a front work extending forward from the right side of the cab 23. The machine 30 and a counterweight 24 provided at the rear of the engine chamber 22 are mainly configured to balance the weight of the front work machine 30.

  The front work machine 30 includes a boom 31 extending forward from the revolving structure frame 40 side, an arm 32 swingably provided at the tip of the boom 31, and a bucket swingably provided at the tip of the arm 32. The boom 31, the arm 32, and the bucket 33 are respectively operated by a boom cylinder 34, an arm cylinder 35, and a bucket cylinder 36 that extend and contract by hydraulic pressure. The boom cylinder 34, the arm cylinder 35, the bucket cylinder 36, the traveling motor 12 and the like are operated by pressure oil (hydraulic oil) supplied from a main pump 50 (FIG. 2) provided in the engine chamber 22. It has become.

The main pump 50 is connected to the engine 70 via the transmission 60 as shown in FIG. 2, and the hydraulic oil in the hydraulic oil tank 80 is supplied to the suction pipe 81 a , the suction tank 82, The suction oil is sucked through the suction pipe 83 and the pressure oil is sent to actuators such as the boom cylinder 34, the arm cylinder 35, the bucket cylinder 36, and the traveling motor 12. A plurality of main pumps 50 are provided for one transmission 60, and the hydraulic oil in the hydraulic oil tank 80 is divided from the suction tank 82 into a plurality of suction pipes 83, 83. ... is being sucked into.

  The high pressure hydraulic oil discharged from the main pumps 50, 50... Is returned from the actuator to the hydraulic oil tank 80 via a return pipe 81b. That is, a large loop circulation path 80A in one direction is formed between the hydraulic oil tank 80 and the main pumps 50, 50... By the suction pipe 81a, the suction tank 82, the suction pipe 83, and the return pipe 81b.

  The transmission 60 is a transmission that accelerates or decelerates the rotational drive of the engine 70 and transmits it to the main pumps 50, 50... By a gear, and is always supplied with lubricating oil (mission oil) by the lubricating pump 61 during operation. It has become so. FIG. 3 is a schematic diagram showing the flow of mission oil in the transmission 60. As shown in the figure, the mission oil sent from the lubrication pump 61 is diverted from the diversion / relay block 62 to the narrow tubes 62a, 62a,... Via the oil feed pipe 61 and supplied to the bearings B, B,. These are lubricated. Further, a part of the mission oil that has flowed to the diversion / relay block 62 flows to the diversion block 63 as it is, and is diverted from the diversion block 63 to the narrow tubes 63a, 63a, etc., to the other bearings B, B,. Supplied to lubricate them.

  Further, the mission oil supplied to the bearings B, B... And the gears flows through the narrow pipes 62b, 62b, 63b, 63b, and flows into the merging blocks 64, 65 to join the return oil pipes 64a, 65a. And return to the lubrication pump 61 side. That is, the mission oil circulates in the circulation path 60A formed by the oil feeding pipe 61a, the thin pipes 62a, 62a,... 62b, 62b, 63a, 63a, 63b, 63b, and the return oil pipes 64a, 65a. It has become. The return oil pipes 64a and 65a are provided with suction filters 64b and 65b, respectively, and when a solid substance such as iron powder is mixed in the mission oil, it is filtered and separated. Yes.

  In this circulation path 60A, a bypass pipe 66 is connected between the oil feed pipe 61 and the return oil pipes 64a and 65a so as to bypass the lubrication pump 61, and a suction filter 64b flowing through the return oil pipes 64a and 65a. The transmission oil immediately after exiting 65b is extracted through the connecting pipe 66a and directly flows in the same direction with respect to the oil feeding pipe 61. Further, the bypass pipe 66 is provided with a preheating unit 67 in which a bypass pump 67a and an electric heater 67b are integrated. The mission oil is extracted to the bypass pipe 66 side by the bypass pump 67b. The mission oil is heated by the heater 67b and then flows to the oil feed pipe 61 side.

  On the other hand, as shown in FIG. 2, a circulation path 70 </ b> A through which cooling water flows is also formed in the engine 70. The circulation path 70A includes a first circulation path 71a formed in the engine 70 and a second circulation path 71b formed between the engine 70 and the radiator. And while circulating the cooling water in the engine 70 with the circulation pump 72 provided in the 1st circulation path 71a and the temperature of the cooling water rises, the thermostat 73 will act | operate and the 1st circulation path 71a and the 1st The second circulating path 71b communicates with the second circulating path 71b, and a high-temperature cooling water is flowed to the second circulating path 71b. The cooling water is cooled by the radiator 74 and the cooling fan 75 and returned to the first circulating path 71a. ing.

  As shown in the figure, a bypass pipe 76 and a preheating unit 77 are also provided in the circulation path 70A of the engine 70 so as to bypass the circulation pump 72 in the same manner as the transmission 60, and flow through the circulation path 70A. The cooling water is extracted and heated, and is returned in the same direction with respect to the circulation path 70A. The preheating unit 77 is also configured by integrating a bypass pump 77a and an electric heater 77b.

  Further, as shown in the figure, the hydraulic oil tank 80 and the suction tank 82 are also connected in parallel with the suction pipe 81a by a bypass pipe 83 having a preheating unit 84, and the bypass pump of the preheating unit 84 is connected. The hydraulic oil in the suction tank 82 is extracted by 84a, and this is heated by the electrothermal heater 84b and returned directly to the middle of the hydraulic oil tank 80. That is, the bypass pipe 83 forms a small loop circuit in parallel with the large loop circuit 80A.

  The operations of the preheating units 67, 77, and 85 are automatically controlled by a controller (information processing device) 90. The controller 90 controls the preheating units 67, 77, and 85 based on various sensors (oil temperature sensor, temperature sensor) not shown and input signals from an engine control unit (ECU).

  FIG. 4 shows a flow of control by the controller 90 regarding the preheating unit 67 for the transmission 60. First, the controller 90 determines whether or not the engine 70 is stopped in the first step S100. When it is determined that the engine 70 is not stopped (NO), the process is terminated, but the engine 70 is stopped. When it is determined that there is (YES), the process proceeds to the next step S102.

  In step S102, it is determined whether or not the outside air temperature is less than −10 ° C. based on the input value from the temperature sensor, and it is determined that there is no risk of the mission oil freezing above −10 ° C., that is, above −10 ° C. If it is (NO), the process is terminated as it is, but if it is determined that the outside air temperature is less than −10 ° C. and there is a possibility of freezing (YES), the process proceeds to the next step S104. In step S104, it is determined whether or not the temperature of the mission oil (oil temperature) is lower than 30 ° C. based on the input value from the oil temperature sensor. If it is determined that the temperature is lower than 30 ° C. (YES), the process proceeds to step S108. Then, the heater 67a of the preheating unit 67 and the bypass pump 67b are started and the mission oil in the circulation path 60A is extracted from the upstream side of the lubrication pump 61 to the bypass pipe 66 side as shown in FIG. Heated at 67b and sent to the downstream side of the lubrication pump 61.

  At this time, since the flow of the mission oil is stopped in the stopped lubrication pump 61, the mission oil sent to the downstream side of the lubrication pump 61 does not flow to the lubrication pump 61 side, as shown in FIG. Flows from the oil feed pipe 61a to the diversion / relay block 62 and the diversion block 63, and passes through the thin tubes 62a, 62a,..., 63a, 63a. After passing sequentially, it flows out from the confluence blocks 64 and 65 to the return oil pipes 64a and 65a, passes through the suction filters 64b and 65b, is extracted to the bypass pipe 66, is heated again by the heater 67b, and circulates in the circulation path 60A. It will be. As a result, the entire transmission 60 is kept at an appropriate temperature, so that it is possible to prevent inconveniences such as the mission oil freezing even when the outside air temperature becomes extremely cold, for example, −40 ° C. or lower.

  On the other hand, when it is determined in step S104 that the temperature (oil temperature) of the mission oil is not lower than 30 ° C., that is, 30 ° C. or higher (NO), the process proceeds to the next step S106 to bypass the preheating unit 67 bypass pump. Only the engine 67b is started, the mission oil in the circulation path 60A is extracted from the upstream side of the lubrication pump 61 to the bypass pipe 66 side, and is sent to the downstream side of the lubrication pump 61. As a result, the mission oil having an oil temperature of 30 ° C. or higher is circulated in the circulation path 60A and the entire transmission 60 is kept at an appropriate temperature by the heat of the mission oil itself, so that unnecessary heating by the heater 67b is prevented and power consumption is reduced. Can be suppressed.

  In the next step S110, it is determined whether or not the oil temperature has become less than 30 ° C. due to a decrease in the outside air temperature during circulation using only the lubrication pump 61, and when it is determined that the oil temperature has not fallen below 30 ° C. (NO) Shifts to step S113, but when it is determined that the temperature is lower than 30 ° C. (YES), the flow shifts to step S112 to further start (energize) the electric heater 67b. Thereby, since the mission oil extracted to the bypass pipe 66 is heated and flows to the circulation path 60A, the mission oil can be more reliably prevented from freezing due to a decrease in the oil temperature. It should be noted that only the heater 67b may be stopped when the oil temperature greatly exceeds 30 ° C. due to the heating of the heater 67b.

  In the next step S114, it is determined whether or not the engine 70 has been started based on an input signal from an ECU (not shown) or the like. When it is determined that the engine 70 has not been started (NO), the circulation of the mission oil is continued as it is, but when it is determined that the engine 70 has been started (YES), the routine proceeds to the next step S116 and the heater 67a. Then, the bypass pump 67b is stopped, the circulation and heating of the mission oil by the preheating unit 67 are stopped, and the processing is ended.

  On the other hand, similarly in step S113, it is determined whether or not the engine 70 has been started based on an input signal from an ECU (not shown), and when it is determined that the engine 70 has not been started (NO), Although the circulation of the mission oil by only the bypass pump 67b is continued, when it is determined that the engine 70 has been started (YES), the process proceeds to the next step S115 to stop the bypass pump 67b, and the preheating unit 67 Stop the mission oil circulation and finish the process. As described above, if the circulation and heating of the mission oil by the preheating unit 67 are finely controlled according to changes in the outside air temperature, oil temperature, etc. while the engine 70 is stopped, efficient preheat treatment can be performed while suppressing wasteful power consumption. Can be implemented.

  The other preheating units 77 and 85 can perform the same control as this to efficiently prevent the hydraulic oil and the cooling water from freezing. In this case, if the starting temperature is appropriately adjusted according to the freezing temperature of each oil type, more efficient preheating can be performed. For example, when the freezing temperature of the mission oil and the cooling water is −10 ° C., whereas the freezing temperature of the hydraulic oil is −20 ° C., when the outside air temperature becomes −10 ° C., If preheating is performed only by 77 and preheating is further performed by the preheating unit 85 on the hydraulic oil tank 80 side when the outside air temperature becomes −20 ° C., further wasteful power consumption can be suppressed. Is possible.

  As described above, according to the present invention, even when the engine 70 is stopped and the circulation of the fluid such as mission oil is stopped in the circulation path 60A of the transmission 60, the fluid is circulated in the same direction via the bypass path 66. Since it can be heated, the entire circulation path 60A can be efficiently preheated. Further, since the bypass pipe 66 is branched from the existing circulation path 60A and the preheating unit 67 is attached to the bypass pipe 66, it can be easily attached to an existing construction machine by retrofitting. , Excellent versatility can be demonstrated. Further, as described above, if the circulation and heating of the mission oil by the preheating unit 67 are finely controlled according to changes in the outside air temperature, oil temperature, etc. while the engine 70 is stopped, it is efficient while suppressing wasteful power consumption. Pre-heat treatment can be performed.

  FIG. 5 shows a conventional configuration example that does not have a preheating unit as in the present invention. That is, the preheating of the cooling water of the engine 70 is performed by attaching the bypass pipe 76 to the circulation path 70A as in the present invention, and extracting the cooling water from the circulation path 70A toward the bypass pipe 76 and heating it. Since the heating means uses a combustion type heater 78, it is difficult to perform good combustion in a place with a low oxygen concentration such as a high altitude, and the configuration is complicated. Further, a plurality of rod heaters 86, 86 are attached to the suction tank 82, and the hydraulic oil in the suction tank 82 is heated by energizing the rod heaters 86. In such a configuration, the heating location is local. It is difficult to efficiently preheat the whole. Further, the transmission 60 that needs to prevent seizure due to freezing of the lubricating oil (mission oil) cannot be efficiently preheated.

  In the present embodiment, the transmission 60 is driven by the engine 70, but it goes without saying that the present invention can be similarly applied when an electric motor is used instead of the engine 70 as a prime mover.

100 ... Construction machine (hydraulic excavator)
DESCRIPTION OF SYMBOLS 50 ... Main pump 60 ... Transmission 60A, 70A, 80A ... Circulation path 61 ... Lubrication pump 66, 76, 84 ... Bypass pipe (path)
67, 77, 85 ... Preheating unit 67a, 77a, 84a ... Electric heater 67b, 77b, 84b ... Bypass pump 70 ... Engine (prime mover)
72 ... Circulating pump 80 ... Hydraulic oil tank 81a ... Suction pipe 81b ... Return pipe 82 ... Suction tank 83 ... Suction pipe 90 ... Controller

Claims (1)

A suction tank is provided in the circulation path for circulating the hydraulic oil between the hydraulic oil tank and the main pump, and a bypass path is provided in parallel between the suction tank and the hydraulic oil tank, and the bypass path and the circulation path are operated. A preheating method for a construction machine that forms a circulation loop of oil and includes a preheating unit including a heater and a bypass pump in the bypass path ,
Measure the outside air temperature and the hydraulic oil temperature when the prime mover is stopped,
When the outside air temperature is lower than the first predetermined value T1 and the hydraulic oil temperature is lower than the second predetermined value T2 (where T1 <T2), the hydraulic oil is heated by the heater of the preheating unit and the bypass pump is used. Implement hydraulic fluid circulation,
Construction in which the working oil is circulated by a bypass pump of the preheating unit when the outside air temperature is lower than the first predetermined value T1 and the hydraulic oil temperature is equal to or higher than the second predetermined value T2. How to preheat the machine.

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