JP6267571B2 - Cooling structure for work machine and power storage device mounted on the work machine - Google Patents

Description

  The present invention relates to an electric or hybrid work machine and a cooling structure for a power storage device mounted thereon.

  As a power storage device for an electric work machine or a hybrid work machine, a lithium ion secondary battery or a capacitor having a high volumetric energy density is used. This type of power storage device is not used as a single cell, but is used after a plurality of cells are combined into a module and adjusted to a predetermined voltage and capacity. In addition, this type of power storage device is used in connection with a control unit incorporating a control circuit and a protection circuit in order to charge and discharge with a predetermined current and to prevent overcharge and overdischarge.

  By the way, characteristics such as voltage and capacity of a lithium ion secondary battery and a capacitor are lowered with the passage of time and repeated charging and discharging, and eventually reach a lifetime. Since the life of the modularized power storage device follows the life of the shortest cell, it is necessary to equalize the life of individual cells in order to extend the life of the power storage device. Cell characteristic deterioration is caused by temperature rise. To extend the life of power storage devices, it is necessary to cool the power storage device and suppress temperature rise due to Joule heat generation during charging and discharging to below the allowable value. There is. In addition, if the temperature distribution of a single cell is large, the electrode is locally deteriorated, which causes a short life of the cell. For this reason, when cooling the power storage device, it is not necessary to simply set the average temperature of a plurality of cells constituting the power storage device below the allowable value, and the temperature of each part of the single cell needs to be below the allowable value.

  Conventionally, as a cooling structure of this type of power storage device, an insulating layer having a thermal conductivity such as a silicon resin sheet (hereinafter, this insulating layer is referred to as a “thermal conductive sheet”) on the bottom surface side of the battery cell constituting the power storage device. ), And a cooling plate is proposed in which the battery cells, the heat conductive sheet, and the cooling plate are fixed in a thermally coupled state. Further, in order to more efficiently conduct heat conduction between the battery cell and the cooling plate, a heat conduction paste such as silicon oil is provided between the heat conduction sheet and the battery cell and between the heat conduction sheet and the cooling plate. The thing which apply | coats is also proposed. Furthermore, in order to reduce the temperature difference between the battery cells, the battery cells arranged at the center of the power storage device are efficiently cooled, and the heat insulating layer is formed so as to reduce the cooling of the battery cells arranged at both ends. Technology has also been proposed (see paragraph 0032 and FIG. 5 of Patent Document 1, paragraph 0034 of Patent Document 1 and FIGS. 7 and 8).

  On the other hand, in Patent Document 2, in view of the fact that the bottom surface of the power storage device is difficult to be completely coplanar and has a stepped shape, the bottom surfaces of all the battery cells are brought into contact with the cooling plate in a uniform state. A technique is disclosed in which a plurality of deformation bodies that are pressed and elastically deformed by a battery stack are provided on a contact surface of the heat conductive sheet with the battery stack. Moreover, this patent document 2 also describes that a heat conductive paste or the like can be used in addition to the heat conductive sheet. Further, this Patent Document 2 discloses a technique for configuring a battery pack by combining a plurality of battery cells and storing a plurality of battery packs in an outer case made up of a lower case, an upper case, and an end face plate. (See the abstract and paragraphs 0017, 0034, FIGS. 1, 5, and 6 of Patent Document 2).

JP 2010-277863 A International Publication No. 2012/147801

  FIG. 5 of Patent Document 1 describes a diagram in which the bottom surfaces of the battery cells aligned with each other are in contact with the heat conductive paste applied to the surface of the heat conductive sheet, and paragraph 0032 of Patent Document 1 Describes that "a structure capable of efficiently conducting heat can be obtained by applying a heat conductive paste on the front and back surfaces of the heat conductive sheet".

  However, Patent Document 1 does not disclose any technology for assembling the power storage device by aligning the bottom surfaces of the battery cells, and no technology for arranging the bottom surface of the power storage device in contact with the heat conductive paste. It is practically extremely difficult or impossible to arrange the battery cell, the heat conductive sheet, the heat conductive paste, and the cooling plate in an ideal state as shown in FIG. That is, as described above, a power storage device used in a work machine or the like is constructed by integrally assembling a plurality of battery cells by using an assembly member such as an outer case. It is practically impossible to arrange the bottom surfaces of the cells in a plane, and it is inevitable that the bottom surfaces of the respective cells have a stepped shape or are inclined with respect to a predetermined reference surface. For this reason, conventionally, an assembly method is generally used in which the bottom surface of the power storage device is pressed against the heat conductive sheet to apply a compressive force to the heat conductive sheet, and all the battery cells are pressed against the heat conductive sheet. is there.

  In order to efficiently dissipate the heat of the battery cell to the cooling plate through the heat conductive sheet, the battery cell is strongly pressed against the heat conductive sheet so that no air layer is interposed between the battery cell and the heat conductive sheet. Therefore, it is necessary to increase the compressibility of the heat conductive sheet. In a conventionally known heat conductive sheet, in order to achieve a predetermined low thermal resistance, it is necessary to press the power storage device so that the compressibility of the heat conductive sheet is 20%. For this reason, when the power storage device having a stepped or inclined bottom surface is pressed, a portion having a high compressibility and a portion having a low compressibility are generated in the heat conductive sheet, and the reaction force against the battery cell becomes excessive. When a high reaction force is applied from the heat conductive sheet to the power storage device, the possibility of damaging the components inside the power storage device increases, so the pressing force that can be applied to the heat conductive sheet is naturally limited. In addition, in a portion where an excessive level difference or inclination occurs, a portion where the bottom surface of the battery cell is not pressed against the heat conductive sheet or a battery cell where the bottom surface does not contact the heat conductive sheet is generated. Variations occur in the situation, and variations in battery cell temperature within the power storage device increase.

  As a method of reducing the reaction force applied to the power storage device while maintaining the heat dissipation efficiency between the battery cell and the cooling plate, a method of reducing the compressibility of the heat conductive sheet using a thick heat conductive sheet is also considered. However, it is not preferable because the heat resistance of the heat conductive sheet increases and the heat dissipation is impaired.

  On the other hand, according to the technique described in Patent Document 2, since a plurality of deformation bodies that are elastically deformed by being pressed by the battery stack are provided on the heat conductive sheet, there is a difference in level between the bottom surface of the battery cells included in the battery stack. Even when there is an inclination, all the battery cells can be easily brought into contact with the heat conductive sheet.

  However, since the heat conductive sheet described in Patent Document 2 has a complicated structure and requires complicated processing for manufacturing, the manufacturing cost is expensive and it is difficult to apply to a work machine.

  The present invention has been made in view of the actual situation of the prior art, and the object thereof is to reduce the temperature, not to exert an excessive reaction force on the power storage device, and to prevent the temperature between a plurality of cells and within a single cell. An object of the present invention is to provide a cooling structure for a power storage device capable of making the distribution uniform, and to provide a work machine having such a cooling structure for a power storage device.

  In order to solve the above problems, the present invention provides a work machine with an engine, a motor / generator for assisting power of the engine and recovering energy from the engine, and power transfer between the motor / generator. An electricity storage device to perform, and a cooling device to cool the electricity storage device, the electricity storage device has a plurality of cells in parallel, the cooling device is a cooling plate disposed to face the bottom surface of the cell, A heat conductive sheet interposed between the cells and the cooling plate; and a heat conductive paste applied to the heat conductive sheet; and immediately below at least one of the plurality of cells, the heat conductive sheet Is not recessed, and the heat conductive paste is interposed between the bottom surface of the cell and the heat conductive sheet.

  According to such a configuration, since at least one of the plurality of cells constituting the power storage device is arranged so as not to deform the heat conductive sheet, the heat conductive sheet is compressed even when there is a step or an inclination on the bottom surface of each cell. The rate can be reduced, and the reaction force applied to the power storage device from the heat conductive sheet can be reduced. Moreover, since the heat conductive paste is interposed between the bottom surface of the cell and the heat conductive sheet, the heat of the cell can be efficiently radiated to the cooling plate side. With the heat conductive paste alone, there is a concern about the electric insulation between the bottom surface of the battery cell and the cooling plate, but since the heat conductive sheet is interposed, the electric insulation can be secured over a long period of time. In view of the above, the life of the power storage device can be extended. Therefore, the life of the power storage device mounted on the work machine can be extended and the operating rate of the work machine can be increased.

  According to the present invention, in the work machine having the above-described configuration, the power storage device includes the plurality of cells, an insulating cell holder disposed between two adjacent cells, and an assembly in which the plurality of cells and the cell holder are assembled together. The power storage device and the cooling device are integrally connected using a connecting member capable of adjusting a distance between a bottom surface of the cell and a heat exchange surface of the cooling plate.

  According to such a configuration, the distance between the bottom surface of the cell and the heat exchange surface of the cooling plate is adjusted by the connecting member that integrally connects the power storage device and the cooling device. It is not necessary to separately provide a special member for adjustment, and the cooling structure of the power storage device can be easily configured.

  On the other hand, regarding the cooling structure of the power storage device, a power storage device having a plurality of cells in parallel, a cooling plate disposed opposite to the bottom surface of the cell, a heat conductive sheet interposed between the cell and the cooling plate, and A cooling device having a heat conductive paste applied to the heat conductive sheet, and immediately below at least one of the plurality of cells, the heat conductive sheet is not recessed, and the bottom surface of the cell and the cell The heat conductive paste is interposed between the heat conductive sheet and the heat conductive sheet.

  According to such a configuration, since at least one of the plurality of cells constituting the power storage device is arranged so as not to deform the heat conductive sheet, the heat conductive sheet is compressed even when there is a step or an inclination on the bottom surface of each cell. The rate can be made relatively small, and the reaction force applied to the power storage device from the heat conductive sheet can be reduced. In addition, since a heat conductive paste is interposed between the bottom surface of the cell and the heat conductive sheet, the heat of the cell can be efficiently dissipated to the cooling plate side, and from this point, the life of the power storage device can be extended. Can do.

  According to the present invention, in the cooling structure for the power storage device having the above-described structure, two protrusions are formed in parallel on the heat exchange surface of the cooling plate with an interval in which the power storage device can be stored. Bending the end portion of the heat conductive sheet along the inner surface of the strip, thereby housing the heat conductive paste and the bottom surface of the power storage device in a recessed portion formed on the surface of the heat conductive sheet; The bottom surface of each cell to be configured and the cooling plate are thermally connected.

  According to such a configuration, since the heat conductive paste can be stored in the recessed portion formed on the surface of the heat conductive sheet, the heat conductive paste flows out of the gap formed between the bottom surface of the cell and the surface of the cooling plate. And the heat dissipation performance of the cell can be kept stable.

  According to the present invention, in the cooling structure of the power storage device having the above-described configuration, the outer peripheral portion of the heat conductive sheet installed on the heat exchange surface of the cooling plate is folded up and the end thereof is disposed on the outer peripheral side of the power storage device. And a holding member for holding an end of the folded heat conductive sheet.

  According to such a configuration, the outer peripheral portion of the heat conductive sheet is folded up and the end thereof is disposed on the outer peripheral side of the power storage device, so that heat from the gap formed between the bottom surface of the cell and the surface of the cooling plate can be obtained. The conductive paste can be prevented from flowing out, and the heat dissipation performance of the cell can be kept stable.

  Further, the present invention is characterized in that a frame body for preventing the heat conductive paste from flowing out is installed on an outer peripheral portion of the heat conductive sheet installed on a heat exchange surface of the cooling plate.

  According to this configuration, since the frame for preventing the heat conductive paste from flowing out is installed on the outer peripheral portion of the heat conductive sheet, the heat from the gap formed between the bottom surface of the cell and the surface of the cooling plate. The conductive paste can be prevented from flowing out, and the heat dissipation performance of the cell can be kept stable.

  According to the present invention, it is possible to efficiently dissipate the heat of the cells to the cooling plate side and reduce the repulsive force from the heat conductive sheet even when the bottom surfaces of the plurality of cells constituting the power storage device have steps or inclinations. it can. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is a side view of a hybrid hydraulic excavator according to an embodiment. It is a block diagram of the power unit mounted in the hybrid type hydraulic excavator which concerns on embodiment. It is a disassembled perspective view of the electrical storage apparatus which concerns on embodiment. It is a figure which shows the assembly method of the cell with which the electrical storage apparatus which concerns on embodiment is equipped, and a cell holder. It is a figure which shows the cooling structure of the electrical storage apparatus which concerns on embodiment. It is a figure which shows the assembly method to the electrical storage apparatus and cooling device which concern on embodiment. It is a figure which shows the positional relationship of the bottom face of a cell, a heat conductive sheet, and a heat conductive paste in the cooling structure of the electrical storage apparatus which concerns on embodiment. It is a principal part enlarged view of FIG. It is A-A 'sectional drawing of FIG. It is a figure which shows the other example of the attachment state of the cell with respect to the cooling plate in the cooling structure of the electrical storage apparatus which concerns on embodiment. It is a figure which shows the cooling cycle of the cooling plate which concerns on embodiment. It is a figure which shows the 1st example of the coating method of the heat conductive paste which concerns on embodiment. It is a figure which shows the 2nd example of the coating method of the heat conductive paste which concerns on embodiment. It is a figure which shows the other example of the heat conductive paste outflow prevention structure which concerns on embodiment. It is a figure which shows the further another example of the heat conductive paste outflow prevention structure which concerns on embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a working machine and a power storage device cooling structure mounted thereon according to the present invention will be described by taking a hybrid hydraulic excavator and a power storage device cooling structure mounted thereon as an example. In addition, this invention is not limited to embodiment described below, In the range which does not deviate from the summary of this invention, it can change arbitrarily and can implement.

  First, the configuration of the hybrid hydraulic excavator according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a side view of a hybrid excavator according to an embodiment, and FIG. 2 is a configuration diagram of a power unit mounted on the hybrid excavator. As shown in FIG. 1, the hybrid hydraulic excavator according to the embodiment includes a traveling body 10 provided with a crawler 11 and its drive wheels 12, a revolving body 20 provided on the traveling body 10 so as to be able to swivel, and a revolving body. 20 includes a power unit 30 mounted on 20 and a front device 40 having one end rotatably connected to the swivel body 20. The drive wheel 12 and the turning body 20 are driven using a hydraulic motor (not shown). In the example of FIG. 1, the traveling body 10 includes the crawler 11, but the traveling body 10 may include a wheel instead of the crawler 11.

  The swivel body 20 includes a swivel frame 21, a driver's cab 22 provided at the front part of the swivel frame 21, and a prime mover room 23 provided at the rear part of the swivel frame 21. The cab 22 includes an operation device 24 for the power unit 30 and a controller 25 that outputs a control signal for the power unit 30 according to the operation amount and operation direction of the operation device 24. On the other hand, a power unit 30 is provided in the prime mover chamber 23.

  As shown in FIG. 2, the power unit 30 is driven by the engine 31, the motor / generator 32 for assisting the power of the engine 31 and recovering energy from the engine 31, and the engine 31 or both the engine 31 and the motor / generator 32. The hydraulic pump 33 is provided. The power storage device 100 is connected to the motor / generator 32 via the inverter 34. The power storage device 100 is provided with a cooling device 200. The hydraulic pump 33 distributes the pressure oil discharged from the hydraulic pump 33 to required hydraulic actuators (a general term for a hydraulic motor that drives the drive wheels 12 and the revolving body 20 and a hydraulic cylinder that drives the front device 40). Connect. The configurations of the power storage device 100 and the cooling device 200 will be described later with reference to the drawings.

  The front device 40 includes a boom 41 whose one end is rotatably connected to the front portion of the swing body 20, a boom hydraulic cylinder 42 that drives the boom 41, and an arm 43 that is rotatably connected to the tip of the boom 41. And an arm hydraulic cylinder 44 for driving the arm 43, a bucket 45 rotatably connected to the tip of the arm 43, a bucket hydraulic cylinder 46 for driving the bucket 45, and the like. Instead of the bucket 45, other attachments such as a breaker, a crusher, a cutter, a grapple, or a lifting magnet can be attached. The hydraulic cylinders 42, 44, 46 and the hydraulic motor described above are driven in a direction corresponding to the operation direction of the operation device 24 at a speed corresponding to the operation amount of the operation device 24.

  The motor / generator 32 is driven by the supply of electric energy from the power storage device 100 to assist in the shortage of output of the engine 31, and converts the regenerative energy recovered from the engine 31 into electric energy to be stored in the power storage device 100. Accumulate electricity. Power transfer between the motor / generator 32 and the power storage device 100 is performed via the inverter 34. The inverter 34 controls the voltage value and frequency of the electric power supplied to the motor / generator 32 based on the control signal output from the controller 25.

  The hybrid hydraulic excavator according to the embodiment is operated by an operator who has boarded the cab 22 operating the operation device 24. That is, when the operator operates the operation device 24, a signal corresponding to the operation amount and operation direction of the operation device 24 is input to the controller 25. The controller 25 outputs a control signal generated based on the input signal, and switches the valve device 35. As a result, the pressure oil discharged from the hydraulic pump 33 is selectively supplied to the required hydraulic cylinders 42, 44, 46 and a hydraulic motor (not shown) at the flow rate, direction and pressure instructed by the operating device 24. Work is performed.

  Next, the power storage device 100 and the cooling device 200 will be described.

  As shown in FIG. 3, power storage device 100 according to the embodiment includes a plurality of cells 110 arranged in parallel in the thickness direction via cell holder 120, and two end plates that abut against the outer surface of cell holder 120 at the outer end. 130 and a frame 140 for connecting the two end plates with screws 141 and assembling the plurality of cells 110 and the cell holder 120 together. The cell 110 can be a battery cell such as a lithium ion secondary battery or a capacitor cell. The end plate 130 is provided with a screw hole 140a for fastening the frame 140 and a screw hole 150a for fastening a bracket 150 described later.

  The cell holder 120 is made of an insulating material, and the portion facing the side surface 111 of the cell 110 has a plurality of ribs 121 arranged in parallel with a predetermined gap therebetween, as shown in FIGS. 4 (a) and 4 (b). Form with. Therefore, as shown in FIG. 4B, even after the cell holder 120 is mounted on the side surface 111 of the cell 110, a part of the side surface 111 of the cell 110 is exposed to the outside air from the gap between the ribs 121 formed on the cell holder 120. Exposed. The frame 140 is formed in a frame shape having an opening 142. With this configuration, the cooling air can be taken in between the ribs 121 of the cell holder 120 through the opening 142, so that the heat stored in the cell 110 can be efficiently radiated.

  When a plurality of cells 110 are electrically connected in series, the directions of the adjacent cells 110 are alternately reversed so that the negative electrode terminal 113b comes next to the positive electrode terminal 112a. Further, two rows of positive electrode terminals 112a and negative electrode terminals 113b arranged in the stacking direction of the cells 110 are connected by a bus bar (not shown), and two positive and negative terminals are taken out. Note that a control board, a cover, and the like are disposed above the terminals, but this is a well-known technique and is not the gist of the present invention, so illustration is omitted.

  As shown in FIG. 5, the cooling device 200 is fixed to the bottom surface of the power storage device 100, that is, the surface opposite to the electrode formation surface of each cell 110 constituting the power storage device 100 using a bracket (connection member) 150. To do. The bracket 150 is made of a metal plate having an L-shaped side surface, and has screw holes 151a and 151b at predetermined positions on each surface as shown in FIG. Among these, the opening position of the screw hole 150a is such that when the power storage device 100 and the cooling device 200 are connected by the screw 131 via the bracket 150, the bottom surface 152 of the bracket is positioned below the bottom surface 111 of the cell 110, and the cell 110 The positional relationship between the bottom surface 111 and the heat conductive sheet 400 described later is adjusted so as to be a predetermined positional relationship described later.

  As shown in FIGS. 5 to 9, the cooling device 200 includes a cooling plate 201, a heat conductive sheet 400 disposed on the heat radiation surface of the cooling plate 201, and a heat conductive paste 300 applied to the surface of the heat conductive sheet 400. Consists of. In the present invention, the heat conductive sheet 400 mainly exhibits a function of ensuring insulation between the cells 110 and the cooling plate 201, and the heat conductive paste 300 mainly performs heat conduction between the cells 110 and the cooling plate 201. Demonstrate the function to ensure the sex.

  The cooling plate 201 has a cooling medium flow path (not shown) inside, and as shown in FIGS. 5 and 6, the cooling plate 201 has an inlet 230 and an outlet 240 for the cooling medium at its ends. Yes. As shown in FIG. 11, the cooling plate 201 circulates the piping 202 connected to the inlet 230 and the outlet 240, the cooling medium radiator 203 connected to the other end of the piping, and the cooling medium in the piping 202. Cooling is performed by a cooling cycle including a circulating pump 204. On the heat exchange surface 210 of the cooling plate 201, that is, the surface on which the power storage device 100 is mounted, as shown in FIG. 6 and FIG. The inner surface of the ridge 220 is an inclined surface whose interval increases toward the upper side, and the set interval of the ridge 220 is set to a size that allows the power storage device 100 to be inserted.

  As shown in FIGS. 6B and 7 to 9, an insulating heat conductive sheet 400 is disposed in close contact with a portion from the heat radiation surface of the cooling plate 201 to the inclined surface of the protrusion 220. Further, an insulating heat conductive paste 300 is applied to the surface of the heat conductive sheet 400 as shown in FIGS. There are various types of heat conductive sheet 400, but in order to improve the adhesion to the bottom surface 111 of the cell 110, for example, a sheet made of an elastic material such as silicon resin is preferable. Further, as the heat conductive paste 300, silicon oil, grease, or the like can be used.

  As shown in FIG. 12, the method of applying the heat conductive paste 300 includes a method of applying the heat conductive paste 300 to the surface of the heat conductive sheet 400, and a method of applying each of the cells 110 constituting the power storage device as shown in FIG. There is a method of applying the heat conductive paste 300 to the bottom surface 111. In the example of FIG. 12, after the heat conductive sheet 400 is installed on the heat radiation surface of the cooling plate 200, the heat conductive paste 300 is waved on the heat conductive sheet 400 while adjusting the discharge amount with a syringe (not shown). It is applied to the mold. When the modularized cell 110 is mounted on the applied heat conductive paste 300, the heat conductive paste 300 is spread and bubbles are pushed out, and the power storage device 100 and the cooling device 200 are thermally coupled. The surplus heat conductive paste 300 moves to the grooves 115 formed between the cells 110. There is no thermal problem even if air accumulates in the groove 115.

  In the example of FIG. 13, the heat conductive paste 300 is applied to each bottom surface 111 with the bottom surface 111 of the cell 110 facing upward and adjusting the discharge amount with a syringe (not shown). Next, when the power storage device 100 in which the heat conductive paste 300 is applied to the bottom surface 111 of the cell 110 is pressed against the heat conductive sheet 400 installed on the heat radiating surface of the cooling plate 200, the heat conductive paste 300 is spread and bubbles are generated. The power storage device 100 and the cooling device 200 are thermally coupled by being pushed out. Also in this case, the surplus heat conductive paste 300 moves to the grooves 115 formed between the cells 110. There is no thermal problem even if air accumulates in the groove 115.

  As shown in FIG. 7, the bottom surface 111 of each cell 110 constituting the power storage device 100 cannot be arranged on the same plane and is usually stepped as shown in FIG. 7 even when the power storage device 100 is carefully assembled. is there. Further, as shown in FIG. 10, it is common that the bottom surface 111 of each cell 110 cannot be parallel to a reference surface, for example, the heat radiating surface of the cooling plate 200, and becomes an inclined surface. Therefore, the bottom surface 111 of each cell 110 needs to be uniformly cooled even when the bottom surface 111 of each cell 110 constituting the power storage device 100 is not arranged flush with each other and becomes a stepped or inclined surface. Moreover, in order to prevent damage to an apparatus, it is necessary to make reaction force from the heat conductive sheet 400 as small as possible.

  In the present embodiment, among the plurality of cells 110 constituting power storage device 100, at least one cell is arranged so that there is no dent in heat conductive sheet 400 immediately below it, and bottom surface 111 of the cell These problems are solved by interposing the heat conductive paste 300 between the heat conductive sheet 400. The mounting height of the cell 110 with respect to the heat exchange surface 210 of the cooling plate 201 is adjusted by adjusting the opening position of the screw hole 150a formed in the bracket 150.

  Hereinafter, the present embodiment will be described in more detail with reference to FIG. In FIG. 8, three cells arranged adjacent to each other are represented by reference numerals 110a, 110b, and 110c, and the bottom surfaces of the respective cells are represented by reference numerals 114a, 114b, and 114c. Moreover, the code | symbol ts0 in a figure shows the thickness of the part which has not produced the initial thickness or the dent of the heat conductive sheet 400. FIG. In the example of FIG. 8, the mounting height of the cell 110c is crs_c and is larger than ts0. Therefore, the heat conductive sheet 400 is not compressed in this portion, and therefore no dent is generated in the heat conductive sheet 400. Paste 300 is present at a thickness of tg_c. The same applies to the cell 110a. Since the heat conductive paste 300 is very soft and can be freely deformed following the steps, it hardly exerts a reaction force on the cells 110a and 110c. On the other hand, since the mounting height of the cell 110b is slightly smaller than ts0, the heat conductive sheet 400 is slightly compressed to form a dent, and the thickness of the portion becomes ts_b. Here, the reaction force from the heat conductive sheet 400 acts on the cell 110b, but since the mounting height of the cells 110a and 110c is set to a position where no depression is generated in the heat conductive sheet 400, the amount of compression of the heat conductive sheet 400 is small. The reaction force will be small accordingly.

  As described above, according to the present embodiment, the heat conductive sheet 400 and the heat conductive paste 300 are interposed between the bottom surfaces 111 of all the cells 110 constituting the power storage device 100 and the heat dissipation surface of the cooling plate 201, Since the compression amount of the heat conductive sheet 400 is limited to a small value, even when there is a step or an inclination on the bottom surface of each cell 110 constituting the power storage device 100, electrical insulation between each cell 110 and the cooling plate 201 is achieved. The bottom surface 111 of each cell 110 can be cooled efficiently and evenly. Moreover, since the compressibility of the heat conductive sheet 400 can be reduced, damage to the device due to the reaction force from the heat conductive sheet 400 can be prevented. Therefore, the life of the power storage device 100 can be extended and the working efficiency of the work machine can be increased.

  Further, the cooling device 200 according to the present embodiment has two ridges 220 protruding in parallel on the heat radiation surface of the cooling plate 201, and the inner surface of these two ridges 220 and the heat radiation surface of the cooling plate 201. Therefore, even when the heat conductive paste 300 is pushed and spread by the power storage device 100, the heat conductive paste 300 is unlikely to flow out of the concave fit portion. Therefore, it is possible to apply a larger amount of the heat conductive paste 300 than when the protrusions 220 are not provided, and even when the bottom surface 111 of the cell 110 has a step or an inclination, the bottom surface 111 of the cell 110 and the heat conductive sheet 400 can be applied. Thus, the heat conductive paste 300 can be reliably filled between the cells 110 and the cells 110 can be cooled uniformly.

  FIG. 14 shows a second example of the cooling structure for the power storage device according to the present invention. The cooling structure of the power storage device according to the present embodiment does not form the protrusions 220 on the cooling plate 201, and folds up the outer peripheral portion of the heat conductive sheet 400 installed on the heat exchange surface 210 of the cooling plate 201, The end portion is arranged on the outer peripheral side of the power storage device 100, and the end portion of the folded heat conductive sheet 400 is held by a holding member 160. Also in this configuration, since the heat conductive paste 300 can be prevented from flowing out, the same effect as when the protrusions 220 are formed on the cooling plate 201 can be exhibited.

  FIG. 15 shows a third example of the cooling structure for the power storage device according to the present invention. In the cooling structure of the power storage device according to the present embodiment, a frame 170 for preventing the heat conductive paste 300 from flowing out is installed on the outer peripheral portion of the heat conductive sheet 400 installed on the heat exchange surface 210 of the cooling plate 201. It is characterized by doing. Also in this configuration, since the heat conductive paste 300 can be prevented from flowing out, the same effects as when the protrusions 220 are formed on the cooling plate 201 and when the end of the heat conductive sheet 400 is folded up are exhibited. it can.

  In the above-described embodiment, a hybrid hydraulic excavator has been described as an example of a work machine. However, the gist of the present invention is not limited to this and can be applied to an electric hydraulic excavator. Moreover, it can be applied not only to the hydraulic excavator but also to other hybrid type and electric type work machines such as a wheel loader, a bulldozer, a crane, and a dump truck.

  In the above-described embodiment, the mounting height of the cell 110 with respect to the heat exchange surface 210 of the cooling plate 201 is adjusted by adjusting the opening position of the screw hole 150a in the bracket 150. However, the bracket 150 and the cooling plate The mounting height of the cell 110 with respect to the heat exchange surface 210 of the cooling plate 201 may be adjusted by interposing a spacer between the heat exchange surface 210 and the heat exchange surface 210 of the cooling plate 201. Moreover, it can also be set as the structure which can change suitably the mounting height of the cell 110 with respect to the heat exchange surface 210 of the cooling plate 201 by making the screw hole 150a into a long hole.

  Furthermore, in the above-described embodiment, the heat conductive paste 300 is applied only to the front surface side of the heat conductive sheet 400. However, in order to improve bubble conduction and increase the heat conduction efficiency, Also, the heat conductive paste 300 can be applied.

31 Engine 32 Motor generator (motor generator)
33 Hydraulic pump 100 Power storage device 110, 110a, 110b, 110c Cell 111, 111a, 111b, 111c Cell bottom surface 120 Cell holder 160 Holding member 170 Frame body 200 Cooling device 201 Cooling plate 210 Heat radiation surface 300 Thermal conductive paste 400 Thermal conductive sheet

Claims (6)

An engine, a motor / generator that performs power assistance of the engine and recovers energy from the engine, a power storage device that transfers power to and from the motor / generator, and a cooling device that cools the power storage device Prepared,
The power storage device includes a plurality of cells arranged in parallel, and the cooling device includes a cooling plate disposed opposite to a bottom surface of the cell, a heat conductive sheet interposed between the cells and the cooling plate, and the heat Having a heat conductive paste applied to the conductive sheet;
The thermal conductive sheet is not recessed immediately below at least one cell among the plurality of cells, and the thermal conductive paste is interposed between the bottom surface of the cell and the thermal conductive sheet. Working machine. The work machine according to claim 1,
The power storage device includes the plurality of cells, an insulating cell holder disposed between two adjacent cells, and an assembly member that integrally assembles the plurality of cells and the cell holder, and the power storage device and the cooling device Is a work machine that is integrally connected using a connection member that can adjust the distance between the bottom surface of the cell and the heat exchange surface of the cooling plate. A power storage device having a plurality of cells arranged in parallel, a cooling plate disposed opposite to the bottom surface of the cells, a heat conductive sheet interposed between the cells and the cooling plate, and a heat conductive paste applied to the heat conductive sheet A cooling device having
The thermal conductive sheet is not recessed immediately below at least one cell among the plurality of cells, and the thermal conductive paste is interposed between the bottom surface of the cell and the thermal conductive sheet. The cooling structure of the power storage device. The power storage device cooling structure according to claim 3,
Two ridges are formed in parallel on the heat exchanging surface of the cooling plate with an interval in which the power storage device can be accommodated, and the end of the heat conductive sheet is bent along the inner surface of the ridge. Thus, the heat conductive paste and the bottom surface of the power storage device are housed in a recess formed on the surface of the heat conductive sheet, and the bottom surface of each cell constituting the power storage device and the cooling plate are thermally connected. A cooling structure for a power storage device, characterized by being connected. The power storage device cooling structure according to claim 3,
Fold up the outer peripheral portion of the heat conductive sheet installed on the heat exchange surface of the cooling plate, place the end portion on the outer peripheral side of the power storage device, and end the folded up heat conductive sheet A cooling structure for a power storage device, comprising a holding member for holding the battery. The power storage device cooling structure according to claim 3,
A cooling structure for a power storage device, wherein a frame for preventing the heat conductive paste from flowing out is provided on an outer peripheral portion of the heat conductive sheet provided on a heat exchange surface of the cooling plate.