Leaf spring device and power conversion device

Abstract

To make an exhibited spring constant higher when a displacement is small and lower when the displacement is large in a process of increasing a push-in load applied in a first direction.SOLUTION: A plate spring device 1 includes a first plate spring portion 11 and a second plate spring portion 12 which are provided on top of the other in a first direction Z between a first pressed body 102 and a second pressed body 101 that oppose each other in the first direction. The first plate spring portion supported by the first pressed body and the second plate spring portion supported by the second pressed body are bent so as to have an apex portion protruding in the first direction. The first plate spring portion has a lower spring constant in the first direction than that of the second plate spring portion. A pushing load in the first direction applied to the plate spring device required to push the first plate spring portion and deform it in the first direction is larger than a pushing load in the first direction applied to the plate spring device required to push the second plate spring portion and deform it in the first direction.SELECTED DRAWING: Figure 2C

Description

Technical Field

[0001] The present invention relates to a leaf spring device and a power conversion device.

Background Art

[0002] Conventionally, for example, as shown in Patent Document 1 below, between a first pressed body and a second pressed body facing each other in a first direction, the first pressed body and the second pressed body are provided so as to be able to press each other in a direction away from each other in the first direction, and a leaf spring curved so as to project in the first direction is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional leaf spring, there is a problem that it is difficult to make the spring constant exhibited high at small displacements and low at large displacements in the process of increasing the applied pressing load in the first direction.

[0005] The present invention has been made in consideration of such circumstances, and an object thereof is to provide a leaf spring device and a power conversion device capable of making the spring constant exhibited high at small displacements and low at large displacements in the process of increasing the applied pressing load in the first direction.

Means for Solving the Problems

[0006] In order to solve the above problems and achieve such an object, the leaf spring device of the present invention includes a first leaf spring portion and a second leaf spring portion that are provided so as to overlap each other in a first direction between a first pressed body and a second pressed body that face each other in the first direction. The first leaf spring portion supported by the first pressed body and the second leaf spring portion supported by the second pressed body are curved so as to have a top portion that protrudes in the first direction. The first leaf spring portion has a lower spring constant in the first direction than the second leaf spring portion. The pressing load in the first direction applied to this leaf spring device required to press and deform the first leaf spring portion in the first direction is larger than the pressing load in the first direction applied to this leaf spring device required to press and deform the second leaf spring portion in the first direction.

[0007] It includes a first leaf spring portion and a second leaf spring portion that are overlapped in the first direction. The spring constant of the first leaf spring portion in the first direction is lower than the spring constant of the second leaf spring portion in the first direction. The pressing load in the first direction applied to this leaf spring device required to press and deform the first leaf spring portion in the first direction is larger than the pressing load in the first direction applied to this leaf spring device required to press and deform the second leaf spring portion in the first direction. Therefore, in the process of increasing the pressing load in the first direction applied to the leaf spring device, first, the second leaf spring portion with a high spring constant in the first direction is pressed and deformed, and then the first leaf spring portion with a low spring constant in the first direction begins to be pressed and deformed. Thereby, in the process of increasing the pressing load in the first direction applied to the leaf spring device, the spring constant that appears can be made high at small displacements and low at large displacements. From the above, even if both the pressing load and the pressing amount applied to the leaf spring device are kept low when assembling the leaf spring device between the first pressed body and the second pressed body, a load of a necessary and sufficient magnitude in the direction of separating the first pressed body and the second pressed body from each other in the first direction can be easily applied to the first pressed body and the second pressed body. That is, when using the first leaf spring portion with a low spring constant in the first direction alone, when attempting to apply the aforementioned load of sufficient magnitude to the first pressed body and the second pressed body, it is necessary to greatly press and deform the first leaf spring portion during the assembly of the leaf spring device to generate a high reaction force in the first leaf spring portion, making this assembly difficult. Also, for example, when using the leaf spring device with the second leaf spring portion having a high spring constant in the first direction in a state where it is pressed in to such an extent that it will not be further pressed and deformed in the first direction, when the first pressed body and the second pressed body relatively approach and move in the first direction, the low spring constant of the first leaf spring portion will be manifested, and the variation in the load in the first direction applied to the first pressed body and the second pressed body can be moderated.

[0008] It may be provided with a holding member that holds the first leaf spring portion in a state where a pressing load for pressing it in the first direction is applied.

[0009] Since it is provided with a holding member that holds the first leaf spring portion in a state where a pressing load is applied, in the process of increasing the pressing load in the first direction applied to the leaf spring device, first, the second leaf spring portion with a high spring constant in the first direction is pressed and deformed, and then, when a pressing load greater than the pressing load previously applied by the holding member is applied to the first leaf spring portion, the first leaf spring portion with a low spring constant in the first direction begins to be pressed and deformed. Thereby, in the process of increasing the pressing load in the first direction applied to the leaf spring device, it is possible to surely realize making the spring constant that is manifested high at small displacements and low at large displacements.

[0010] It may be provided with a restricting portion that restricts further pressing deformation of the second leaf spring portion in the first direction when the second leaf spring portion is pressed in the first direction.

[0011] Since it is provided with a restricting portion that restricts further pushing deformation of the second leaf spring portion in the first direction when the second leaf spring portion is pushed and deformed in the first direction, in the process of increasing the pushing load in the first direction applied to the leaf spring device, first, the second leaf spring portion having a high spring constant in the first direction is pushed and deformed, and then, with the further pushing deformation of the second leaf spring portion restricted by the restricting portion, the first leaf spring portion having a low spring constant in the first direction begins to be pushed and deformed. As a result, in the process of increasing the pushing load in the first direction applied to the leaf spring device, it is possible to surely realize making the spring constant exhibited high at a small displacement and low at a large displacement.

[0012] When the restricting portion restricts further pushing deformation of the second leaf spring portion in the first direction, the pushing load in the first direction applied to this leaf spring device may be equal to or greater than the pushing load in the first direction applied to this leaf spring device when the first leaf spring portion begins to be pushed and deformed in the first direction.

[0013] As a result, in the process of increasing the pushing load in the first direction applied to the leaf spring device, the spring constant in the first direction exhibited by the leaf spring device can be smoothly switched without restricting the pushing deformation in the first direction of the leaf spring device.

[0014] The first leaf spring portion and the second leaf spring portion are provided so as to be curved in opposite directions to each other in the first direction and the tops thereof overlap in the first direction, and the restricting portion may be provided between the top of the second leaf spring portion and the second pressed body.

[0015] Since the first leaf spring portion and the second leaf spring portion are curved in opposite directions to each other in the first direction and the respective tops thereof overlap in the first direction, it becomes possible to easily secure a wide space between the top of the second leaf spring portion and the second pressed body, and it is possible to make it difficult to impose restrictions on the size of the restricting portion provided in this portion. Therefore, when the restricting portion restricts further pushing deformation of the second leaf spring portion in the first direction, it is possible to easily set the pushing load in the first direction applied to this leaf spring device.

[0016] The holding member may include a seat plate provided between the first leaf spring portion and the first pressed body, and a connecting portion that connects the restricting portion and the seat plate in the first direction.

[0017] Since the holding member includes a connecting portion that connects the restricting portion and the seat plate, the number of parts can be suppressed. For example, it is not necessary to provide a locking portion of the holding member on the first pressed body, and the first pressed body can be used as it is without design change. Since the connecting portion connects a seat plate provided between the first leaf spring portion and the first pressed body and a restricting portion provided between the top of the second leaf spring portion and the second pressed body, the holding member and the restricting portion also serve as connecting members that connect the first leaf spring portion and the second leaf spring portion to each other in the first direction. The relative displacement of the first leaf spring portion and the second leaf spring portion in a direction intersecting the first direction is suppressed, and the characteristics exhibited by the leaf spring device with respect to the pushing load in the first direction applied to the leaf spring device can be stabilized.

[0018] The first leaf spring portion and the second leaf spring portion may include a connecting member that connects them to each other in the first direction.

[0019] Since the first leaf spring portion and the second leaf spring portion include a connecting member that connects them to each other in the first direction, it becomes possible to suppress the relative displacement of the first leaf spring portion and the second leaf spring portion in a direction intersecting the first direction, and the characteristics exhibited by the leaf spring device with respect to the pushing load in the first direction applied to the leaf spring device can be stabilized.

[0020] The power conversion device of the present invention is a power conversion device in which a semiconductor stack unit and the leaf spring device of the present invention are housed in a housing in a state of being arranged in the first direction. The semiconductor stack unit includes at least one semiconductor module and one cooling pipe alternately arranged in the first direction. One of the first pressed body and the second pressed body serves as the housing, and the other serves as the semiconductor stack unit.

[0021] When assembling the leaf spring device between the housing and the semiconductor stack unit, even if both the pushing load and the pushing amount applied to the leaf spring device are kept lower than those in the case of using the first leaf spring portion with a low spring constant in the first direction alone, a load of a sufficient magnitude in a direction separating the housing and the semiconductor stack unit from each other in the first direction can be easily applied to the housing and the semiconductor stack unit. Further, for example, when using the leaf spring device with the second leaf spring portion having a high spring constant in the first direction pushed in to such an extent that it does not deform further in the first direction, when the housing and the semiconductor stack unit relatively approach and move in the first direction, the low spring constant of the first leaf spring portion will be manifested, and the load fluctuation in the first direction generated in the housing and the semiconductor stack unit can be alleviated.

Advantages of the Invention

[0022] According to this invention, in the process of increasing the pushing load in the first direction applied to the leaf spring device, the spring constant to be manifested can be made high at small displacements and low at large displacements.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 3

Figure 4A

Figure 4B

Figure 5A

Figure 5B

Figure 6

DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, an embodiment of the leaf spring device 1 and the power conversion device 10 will be described with reference to FIGS. 1 and 2A to 2D. The power conversion device 10 is configured such that a semiconductor stack unit 101 and a leaf spring device 1 are housed in a housing 102 in a state of being arranged in the first direction Z, and generates, for example, a drive current supplied to a traveling motor for an electric vehicle. In the illustrated example, a flat contact plate 106 is provided between the semiconductor stack unit 101 and the leaf spring device 1.

[0025] The semiconductor stack unit 101 includes a plurality of semiconductor modules 103 and cooling pipes 104 alternately arranged in the first direction Z. Note that the semiconductor modules 103 and the cooling pipes 104 may be provided one by one, or may be provided with different numbers from each other.

[0026] The semiconductor module 103 includes a pair of heat sinks provided at intervals in the first direction Z, an IGBT element for power supply, a flywheel diode element for smoothly driving a traveling motor, and a sealing material. Note that the semiconductor module 103 may be changed as appropriate. The IGBT element and the flywheel diode element are provided between the pair of heat sinks. The sealing material is formed of a resin material, connects the pair of heat sinks in a state where the heat sinks are exposed, and seals the IGBT element and the flywheel diode element. In the illustrated example, a plurality of semiconductor modules 103 are provided at intervals in the second direction X orthogonal to the first direction Z between the cooling pipes 104 adjacent to each other in the first direction Z.

[0027] The cooling pipe 104 is formed in a flat shape crushed in the first direction Z. A refrigerant flows in the cooling pipe 104. The interiors of the plurality of cooling pipes 104 communicate with each other through a connecting pipe 105 extending in the first direction Z. A plurality of connecting pipes 105 are provided at intervals in the second direction X. Refrigerant is supplied from a supply unit to one of the plurality of connecting pipes 105, and is discharged from the other one toward the supply unit. The cooling pipe 104 is pressed against the heat sink of the semiconductor module 103 by a pressing load in the first direction Z from the leaf spring device 1.

[0028] One leaf spring device 1 is provided between the semiconductor stacked unit 101 and the inner surface of the housing 102 facing each other in the first direction Z. Note that a plurality of leaf spring devices 1 may be provided at intervals in the second direction X. The leaf spring device 1 includes a first leaf spring portion 11 and a second leaf spring portion 12 provided to be stacked in the first direction Z. The first leaf spring portion 11 and the second leaf spring portion 12 are curved so as to have a top portion protruding in the first direction Z.

[0029] In the illustrated example, the first leaf spring portion 11 and the second leaf spring portion 12 are plate bodies having short sides extending in the third direction Y orthogonal to the second direction X and long sides extending in the second direction X when viewed from the first direction Z. The top portion is formed at the central portion of the second direction X in each of the first leaf spring portion 11 and the second leaf spring portion 12.

[0030] Note that the top portion may be formed at a position away from the second direction X from the central portion of the second direction X in each of the first leaf spring portion 11 and the second leaf spring portion 12. When viewed from the first direction Z, the directions in which the long sides of each of the first leaf spring portion 11 and the second leaf spring portion 12 extend may be different from each other.

[0031] The first leaf spring portion 11 and the second leaf spring portion 12 are curved in opposite directions to each other in the first direction Z, and the top portions are provided so as to overlap each other in the first direction Z.

[0032] Note that the top portions of each of the first leaf spring portion 11 and the second leaf spring portion 12 may be fixed by welding, adhesion, or the like. Further, the top portions of each of the first leaf spring portion 11 and the second leaf spring portion 12 may be wound and fixed to both ends in the third direction Y of one of the top portions of the first leaf spring portion 11 and the second leaf spring portion 12 at both ends in the third direction Y of the other top portion. Also, the surfaces of the top portions of each of the first leaf spring portion 11 and the second leaf spring portion 12 that abut against each other may be formed flat.

[0033] In the illustrated example, the first leaf spring portion 11 is supported by a housing (first pressed body) 102 via a seat plate 14 described later, and the second leaf spring portion 12 is supported by a semiconductor stacked unit (second pressed body) 101 via a contact plate 106. The top portion of the first leaf spring portion 11 bulges toward the semiconductor stacked unit 101 side along the first direction Z, and the top portion of the second leaf spring portion 12 bulges toward the housing 102 side along the first direction Z. Both ends of the first leaf spring portion 11 in the second direction X are slidably in contact with the seat plate 14 described later. Both ends of the second leaf spring portion 12 in the second direction X are slidably in contact with the contact plate 106.

[0034] The spring constant of the first leaf spring portion 11 in the first direction Z is lower than the spring constant of the second leaf spring portion 12 in the first direction Z. Before being assembled to the power conversion device 10 as shown in FIGS. 2A and 2B, the pushing load in the first direction Z applied to this leaf spring device 1 required to push and deform the first leaf spring portion 11 in the first direction Z is greater than the pushing load in the first direction Z applied to this leaf spring device 1 required to push and deform the second leaf spring portion 12 in the first direction Z. When the first leaf spring portion 11 and the second leaf spring portion 12 are pushed and deformed in the first direction Z, they elastically deform in a direction extending in the second direction X and shrinking in the first direction Z, that is, in a direction of becoming flat.

[0035] In the present embodiment, a restricting portion 13 is provided that restricts further pushing and deformation of the second leaf spring portion 12 in the first direction Z when the second leaf spring portion 12 is pushed in the first direction Z.

[0036] The restricting portion 13 is provided between the top portion of the second leaf spring portion 12 and the contact plate 106 (semiconductor stack unit 101). The restricting portion 13 is attached to the top portion of the second leaf spring portion 12. The restricting portion 13 is in contact with or close to the contact plate 106 as shown in FIGS. 1 and 2C. Before the leaf spring device 1 is assembled to the power conversion device 10, as shown in FIGS. 2A and 2B, the restricting portion 13 is located on the side of the housing 102 along the first direction Z from both end portions of the second leaf spring portion 12 in the second direction X, that is, at a position away from the contact plate 106 in the first direction Z. The restricting portion 13 is formed in a plate shape with its front and back surfaces facing the first direction Z. By being sandwiched and contacting the top portion of the second leaf spring portion 12 and the contact plate 106 in the first direction Z, further pushing deformation of the second leaf spring portion 12 in the first direction Z is restricted.

[0037] When the restricting portion 13 restricts further pushing deformation of the second leaf spring portion 12 in the first direction Z as shown in FIG. 2C, the pushing load in the first direction Z applied to this leaf spring device 1 is equal to or greater than the pushing load in the first direction Z applied to this leaf spring device 1 when the first leaf spring portion 11 begins to be pushed and deformed in the first direction Z. In the present embodiment, the former pushing load is the same as the latter pushing load.

[0038] A holding member 16 is provided to hold the first leaf spring portion 11 in a state where a pushing load for pushing the first leaf spring portion 11 in the first direction Z is applied, starting from before the leaf spring device 1 is assembled to the power conversion device 10. In the illustrated example, the holding member 16 includes a seat plate 14 and a connecting portion 15.

[0039] The seat plate 14 is a flat plate with its front and back surfaces facing the first direction Z, and is provided between the first leaf spring portion 11 and the housing 102. The seat plate 14 slidably supports both end portions of the first leaf spring portion 11 in the second direction X. The connecting portion 15 connects the restricting portion 13 and the seat plate 14 in the first direction Z. The connecting portion 15 penetrates through the first leaf spring portion 11 and the second leaf spring portion 12 integrally in the first direction Z. The first leaf spring portion 11 and the second leaf spring portion 12 are provided movably in the first direction Z on the connecting portion 15.

[0040] A tensile force in the first direction Z is applied to the connecting portion 15. As a result, a pushing load in the first direction Z is applied to the first leaf spring portion 11, and with both end portions of the first leaf spring portion 11 in the second direction X being in pressure contact with the seat plate 14, the first leaf spring portion 11 is elastically deformed in a direction extending in the second direction X and contracting in the first direction Z. That is, the first leaf spring portion 11 is held in a state of being pushed and deformed in the first direction Z. By changing the tensile force in the first direction Z applied to the connecting portion 15, it is possible to adjust the pushing load in the first direction Z applied to this leaf spring device 1 when the first leaf spring portion 11 starts to be pushed and deformed in the first direction Z.

[0041] In the illustrated example, a recess is formed in the surface of the seat plate 14 facing the housing 102 side along the first direction Z. A flat plate 14a is accommodated in the recess. In the recess, the connecting portion 15 penetrates the seat plate 14 in the first direction Z and is connected to the flat plate 14a. Note that the flat plate 14a may be formed integrally with the seat plate 14. The connecting portion 15 has a tensile strength capable of holding the first leaf spring portion 11 in a state where a pushing load in the first direction Z is applied, and in the process of increasing the pushing load in the first direction Z applied to the leaf spring device 1, it is not affected by, or has little effect on, the pushing deformation of the first leaf spring portion 11 and the second leaf spring portion 12, and is easily deformable, for example, is composed of a wire or the like. Note that a rigid pin or the like that is difficult to deform may be adopted as the connecting portion, and a recess portion into which the connecting portion and the flat plate 14a can enter in the first direction Z may be provided in the housing 102.

[0042] Since the connecting portion 15 connects the seat plate 14 provided between the first leaf spring portion 11 and the housing 102 and the regulating portion 13 provided between the top portion of the second leaf spring portion 12 and the contact plate 106, the holding member 16 and the regulating portion 13 also serve as a connecting member 17 that connects the top portions of the first leaf spring portion 11 and the second leaf spring portion 12 to each other in the first direction Z. Note that a plurality of connecting members 17 (holding member 16 and regulating portion 13) may be provided, for example, at intervals in the third direction Y.

[0043] Before the leaf spring device 1 is assembled to the power conversion device 10 as shown in FIGS. 2A and 2B, in the process of increasing the pushing load in the first direction Z applied to the leaf spring device 1, first, the second leaf spring portion 12 with a high spring constant in the first direction Z, to which the pushing load in the first direction Z is not initially applied, is pushed and deformed, and then, the first leaf spring portion 11 with a low spring constant in the first direction Z, to which the pushing load in the first direction Z is initially applied by the holding member 16, begins to be pushed and deformed.

[0044] At this time, in the present embodiment, as shown in FIG. 2C, when the regulating portion 13 restricts further pushing deformation of the second leaf spring portion 12 in the first direction Z, the pushing load in the first direction Z applied to this leaf spring device 1 is the same as the pushing load in the first direction Z applied to this leaf spring device 1 when the first leaf spring portion 11 begins to be pushed and deformed in the first direction Z. Therefore, almost simultaneously with the regulating portion 13 restricting further pushing deformation of the second leaf spring portion 12, a pushing load greater than the pushing load previously applied by the holding member 16 is applied to the first leaf spring portion 11, and the first leaf spring portion 11 begins to be pushed and deformed. As the first leaf spring portion 11 is pushed and deformed, as shown in FIG. 2D, the connecting portion 15 is deformed.

[0045] As shown in FIGS. 1 and 2C, in the state where the leaf spring device 1 is assembled to the power conversion device 10, since the second leaf spring portion 12 is pushed in the first direction Z, the regulating portion 13 abuts or approaches the contact plate 106, while no load other than the pushing load previously applied by the holding member 16 is applied to the first leaf spring portion 11. Note that in the state where the leaf spring device 1 is assembled to the power conversion device 10, the regulating portion 13 may be separated from the contact plate 106 in the first direction Z.

[0046] As described above, according to the leaf spring device 1 according to the present embodiment, the leaf spring device 1 includes a first leaf spring portion 11 and a second leaf spring portion 12 stacked in the first direction Z, and the spring constant of the first leaf spring portion 11 in the first direction Z is lower than the spring constant of the second leaf spring portion 12 in the first direction Z. The pushing load in the first direction Z applied to the leaf spring device 1 required to push and deform the first leaf spring portion 11 in the first direction Z is greater than the pushing load in the first direction Z applied to the leaf spring device 1 required to push and deform the second leaf spring portion 12 in the first direction Z.

[0047] Therefore, before the leaf spring device 1 is assembled to the power conversion device 10 as shown in FIGS. 2A and 2B (hereinafter referred to as the leaf spring device 1 alone), in the process of increasing the pushing load in the first direction Z applied to the leaf spring device 1, first, the second leaf spring portion 12 with a high spring constant in the first direction Z is pushed and deformed, and then, the first leaf spring portion 11 with a low spring constant in the first direction Z begins to be pushed and deformed. Thereby, in the process of increasing the pushing load in the first direction Z applied to the leaf spring device 1, the spring constant that appears can be made high at small displacements and low at large displacements.

[0048] From the above, when assembling the leaf spring device 1 between the housing 102 and the semiconductor stack unit 101, even if both the pushing load and the pushing amount applied to the leaf spring device 1 are kept lower than those when using the first leaf spring portion 11 with a low spring constant in the first direction Z alone, a load of a sufficient magnitude in the direction of separating the housing 102 and the semiconductor stack unit 101 from each other in the first direction Z can be easily applied to the housing 102 and the semiconductor stack unit 101. That is, when using the first leaf spring portion 11 with a low spring constant in the first direction Z alone, when trying to apply the above-mentioned load of a sufficient magnitude to the housing 102 and the semiconductor stack unit 101, it is necessary to greatly push and deform the first leaf spring portion 11 during the assembly of the leaf spring device 1 to generate a high reaction force in the first leaf spring portion 11, making this assembly difficult.

[0049] Further, for example, when using the leaf spring device 1 with the second leaf spring portion 12 having a high spring constant in the first direction Z being pushed in to such an extent that it will not be pushed in any further in the first direction Z, when the housing 102 and the semiconductor laminate unit 101 move relatively closer in the first direction Z due to, for example, thermal expansion of the semiconductor module 103, etc., the low spring constant of the first leaf spring portion 11 will be exhibited, and the load fluctuation in the first direction Z generated in the housing 102 and the semiconductor laminate unit 101 can be moderated.

[0050] Since it is provided with the holding member 16 that holds the first leaf spring portion 11 in a state where a pushing load is applied, in the leaf spring device 1 alone, in the process of increasing the pushing load in the first direction Z applied to the leaf spring device 1, first, the second leaf spring portion 12 having a high spring constant in the first direction Z is pushed in and deformed, and then, when a pushing load greater than the pushing load previously applied by the holding member 16 is applied to the first leaf spring portion 11, the first leaf spring portion 11 having a low spring constant in the first direction Z begins to be pushed in and deformed. Thereby, in the process of increasing the pushing load in the first direction Z applied to the leaf spring device 1, it is possible to surely realize making the spring constant exhibited high at the time of small displacement and low at the time of large displacement.

[0051] Since it is provided with the restricting portion 13 that restricts further pushing deformation of the second leaf spring portion 12 in the first direction Z when the second leaf spring portion 12 is pushed in and deformed in the first direction Z, in the leaf spring device 1 alone, in the process of increasing the pushing load in the first direction Z applied to the leaf spring device 1, first, the second leaf spring portion 12 having a high spring constant in the first direction Z is pushed in and deformed, and then, in a state where further pushing deformation of the second leaf spring portion 12 is restricted by the restricting portion 13, the first leaf spring portion 11 having a low spring constant in the first direction Z begins to be pushed in and deformed. Thereby, in the process of increasing the pushing load in the first direction Z applied to the leaf spring device 1, it is possible to surely realize making the spring constant exhibited high at the time of small displacement and low at the time of large displacement.

[0052] When the restricting portion 13 restricts further pushing deformation of the second leaf spring portion 12 in the first direction Z, the pushing load in the first direction Z applied to the leaf spring device 1 is equal to or greater than the pushing load in the first direction Z applied to the leaf spring device 1 when the first leaf spring portion 11 begins to be pushed and deformed in the first direction Z. Therefore, in the process of increasing the pushing load in the first direction Z applied to the leaf spring device 1 with the leaf spring device 1 alone, the pushing deformation of the leaf spring device 1 in the first direction Z can be smoothly switched without being restricted, and the spring constant of the leaf spring device 1 in the first direction Z can be smoothly switched.

[0053] Since the first leaf spring portion 11 and the second leaf spring portion 12 are curved in opposite directions to each other in the first direction Z and the respective tops thereof overlap in the first direction Z, a wide space can be easily secured between the top of the second leaf spring portion 12 and the contact plate 106 (semiconductor stacked unit 101), and it is possible to make it difficult to impose restrictions on the size of the restricting portion 13 provided in this portion. Therefore, when the restricting portion 13 restricts further pushing deformation of the second leaf spring portion 12 in the first direction Z, the pushing load in the first direction Z applied to the leaf spring device 1 can be easily set.

[0054] Since the holding member 16 includes a connecting portion 15 that connects the restricting portion 13 and the seat plate 14, the number of parts can be reduced. For example, it is not necessary to provide a locking portion of the holding member 16 on the housing 102, and the housing 102 can be used as it is without design changes.

[0055] Since the connecting portion 15 connects the seat plate 14 provided between the first leaf spring portion 11 and the housing 102 and the restricting portion 13 provided between the top of the second leaf spring portion 12 and the contact plate 106, the holding member 16 and the restricting portion 13 also serve as a connecting member 17 that connects the first leaf spring portion 11 and the second leaf spring portion 12 to each other in the first direction Z, and relative displacement of the first leaf spring portion 11 and the second leaf spring portion 12 in a direction intersecting the first direction Z can be suppressed, and the characteristics exhibited by the leaf spring device 1 with respect to the pushing load in the first direction Z applied to the leaf spring device 1 can be stabilized.

[0056] Next, the leaf spring device 2 according to the second embodiment of the present invention will be described with reference to FIG. 3. In this second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted, and only the differences will be described.

[0057] In the leaf spring device 2 of this embodiment, when the second leaf spring portion 12 is pushed into the first direction Z, a restricting portion 23 that restricts further pushing deformation of the second leaf spring portion 12 in the first direction Z penetrates the first leaf spring portion 11 and the second leaf spring portion 12 integrally in the first direction Z. The restricting portion 23 sandwiches the top portions of the first leaf spring portion 11 and the second leaf spring portion 12 in the first direction Z. The restricting portion 23 also serves as a connecting member 17 that connects the first leaf spring portion 11 and the second leaf spring portion 12 to each other in the first direction Z. The restricting portion 23 is a rivet.

[0058] As described above, according to the leaf spring device 2 of this embodiment, similar to the leaf spring device 1 of the first embodiment, in the process of increasing the applied pushing load in the first direction Z, the spring constant that appears can be made high at small displacements and low at large displacements, etc.

[0059] Next, the leaf spring device 3 according to the third embodiment of the present invention will be described with reference to FIGS. 4A and 4B. In this third embodiment, the same components as those in the second embodiment are denoted by the same reference numerals, and the description thereof is omitted, and only the differences will be described.

[0060] In the leaf spring device 3 of this embodiment, a holding member 36 that holds the first leaf spring portion 11 in a state where a pushing load for pushing it into the first direction Z is applied includes a seat plate 14 and a locking portion 36a, and the connecting portion 15 and the flat plate 14a are not provided.

[0061] Both end portions of the first leaf spring portion 11 in the third direction Y protrude outward in the third direction Y from both end portions of the second leaf spring portion 12 in the third direction Y. The engaging portion 36a projects from each portion of the seat plate 14 located outside the first leaf spring portion 11 and the second leaf spring portion 12 in the third direction Y toward the semiconductor stack unit 101 along the first direction Z, and engages with both ends of the first leaf spring portion 11 in the third direction Y at the top portion thereof separately. The engaging portion 36a is formed integrally with the seat plate 14. The tip portion 36b of the engaging portion 36a on the semiconductor stack unit 101 side along the first direction Z projects toward the inside of the third direction Y and abuts against the surface of the top portion of the first leaf spring portion 11 facing the semiconductor stack unit 101 side along the first direction Z. The distance between the tip portions 36b of the pair of engaging portions 36a facing each other in the third direction Y is larger than the size of the semiconductor stack unit 101 in the third direction Y. The semiconductor stack unit 101 is provided so as to move forward and backward between the tip portions 36b of the pair of engaging portions 36a as it moves in the first direction Z.

[0062] In addition, the sizes of the first leaf spring portion 11 and the second leaf spring portion 12 in the third direction Y may be the same as each other, and the positions of the central portions of the first leaf spring portion 11 and the second leaf spring portion 12 in the third direction Y may be made to coincide with each other. The tip portion 36b of the engaging portion 36a may be brought into contact with the surface of the top portion of the second leaf spring portion 12 facing the semiconductor stack unit 101 side along the first direction Z. The engaging portion 36a may be separate from the seat plate 14.

[0063] As described above, according to the leaf spring device 3 according to the present embodiment, similar to the leaf spring device 1 of the first embodiment, in the process of increasing the applied pushing load in the first direction Z, the spring constant to be exhibited can be made high at the time of small displacement and low at the time of large displacement, etc.

[0064] Next, a leaf spring device 4 according to a fourth embodiment of the present invention will be described with reference to FIGS. 5A and 5B. In this fourth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted, and only the different points will be described.

[0065] In the leaf spring device 4 of the present embodiment, the second leaf spring portion 42 bulges toward the semiconductor laminate unit 101 along the first direction Z, and the first leaf spring portion 11 and the second leaf spring portion 42 are curved in the same direction of the first direction Z. When viewed from the third direction Y, the radius of curvature of the first leaf spring portion 11 is larger than the radius of curvature of the second leaf spring portion 42. The top of the first leaf spring portion 11 faces the top of the second leaf spring portion 12 in the first direction Z. Both end portions of the second leaf spring portion 42 in the second direction X are slidably in contact with the surface of the first leaf spring portion 11 facing the semiconductor laminate unit 101 side along the first direction Z. The top of the second leaf spring portion 42 is supported by the semiconductor laminate unit 101 via the contact plate 106.

[0066] The restricting portion 13 is provided between the top of the first leaf spring portion 11 and the top of the second leaf spring portion 42. The restricting portion 13 is attached to the top of the first leaf spring portion 11. Before the leaf spring device 1 is assembled to the power conversion device 10, the restricting portion 13 is separated from the top of the second leaf spring portion 12 in the first direction Z. When the second leaf spring portion 42 is pushed into the first direction Z and the restricting portion 13 comes into contact with the top of the second leaf spring portion 42, further pushing deformation of the second leaf spring portion 12 in the first direction Z is restricted.

[0067] Connecting members 47 that connect the first leaf spring portion 11 and the second leaf spring portion 42 to each other in the first direction Z are provided on both sides sandwiching the restricting portion 13 in the third direction Y. The connecting member 47 includes a first flat plate 47a provided on the surface of the first leaf spring portion 11 facing the housing 102 side along the first direction Z, a second flat plate 47b provided on the surface side of the second leaf spring portion 42 facing the semiconductor laminate unit 101 side along the first direction Z, and a connecting portion 47c that connects the first flat plate 47a and the second flat plate 47b to each other in the first direction Z.

[0068] A recess in which the second flat plate 47b is accommodated is formed in the surface of the second leaf spring portion 42 facing the semiconductor laminate unit 101 side along the first direction Z. The connecting portion 47c penetrates the top portions of the first leaf spring portion 11 and the second leaf spring portion 42 in the first direction Z. The connecting portion 47c is formed of a deformable member such as a wire. The first leaf spring portion 11 and the second leaf spring portion 42 are movably provided in the first direction Z on the connecting portion 47c. A tensile force in the first direction Z is not applied to the connecting portion 47c, and the connecting member 47 does not push and deform the second leaf spring portion 42 in the first direction Z.

[0069] Note that, as the connecting member 47, a configuration may be adopted in which the connecting member 47 is provided at the central portion in the third direction Y of the leaf spring device 4, does not have the first flat plate 47a, and the connecting portion 47c connects the second flat plate 47b and the restricting portion 13 in the first direction Z. The connecting member 47 may not be provided.

[0070] As described above, according to the leaf spring device 4 of the present embodiment, similar to the leaf spring device 1 of the first embodiment, in the process of increasing the applied pushing load in the first direction Z, the spring constant to be exhibited can be made high at small displacements and low at large displacements.

[0071] Next, a leaf spring device 5 according to a fifth embodiment of the present invention will be described with reference to FIG. 6. In this fifth embodiment, the same components as those in the fourth embodiment are denoted by the same reference numerals, and the description thereof is omitted, and only the differences will be described.

[0072] In the leaf spring device 5 of the present embodiment, the connecting member 47 is not provided, and a recess 52a into which the restricting portion 13 enters when the second leaf spring portion 52 is pushed in the first direction Z is formed at the top of the second leaf spring portion 52. The recess 52a penetrates the second leaf spring portion 52 in the first direction Z. Note that the recess 52a does not have to penetrate the second leaf spring portion 52 in the first direction Z. When the second leaf spring portion 52 is pushed into the first direction Z, the restricting portion 13 enters the recess 52a, and the second leaf spring portion 52 abuts against both the contact plate 106 and the top of the first leaf spring portion 11, thereby restricting further pushing deformation of the second leaf spring portion 52 in the first direction Z.

[0073] Note that when the second leaf spring portion 52 is pushed into the first direction Z, a configuration may be adopted in which the restricting portion 13 enters the recess 52a and abuts against the contact plate 106, thereby restricting further pushing deformation of the second leaf spring portion 52 in the first direction Z.

[0074] As described above, according to the leaf spring device 5 according to the present embodiment, similar to the leaf spring device 1 of the first embodiment, in the process of increasing the applied pushing load in the first direction Z, the spring constant that appears can be made high at small displacements and low at large displacements.

[0075] Note that the technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0076] For example, the leaf spring devices 1 to 5 may be applied not only to the power conversion device 10 but also to other devices. The first leaf spring portion 11 may be supported by the semiconductor stack unit 101 via the contact plate 106, and the second leaf spring portions 12, 42, 52 may be supported by the housing 102.

[0077] When the restricting portions 13, 23 restrict further pushing deformation of the second leaf spring portions 12, 42, 52 in the first direction Z, and when the first leaf spring portion 11 starts to be pushed and deformed in the first direction Z, the pushing loads in the first direction Z applied to the leaf spring devices 1 to 5 may be made different from each other. That is, when the restricting parts 13 and 23 restrict further pushing deformation of the second leaf spring parts 12, 42, and 52 in the first direction Z, the pushing load in the first direction Z applied to these leaf spring devices 1 to 5 may be made larger or smaller than the pushing load in the first direction Z applied to these leaf spring devices 1 to 5 when the first leaf spring part 11 begins to be pushed and deformed in the first direction Z. When the former pushing load is larger than the latter pushing load, in the process of increasing the pushing load in the first direction Z applied to the single leaf spring devices 1 to 5 before assembly, the pushing deformation of the leaf spring devices 1 to 5 in the first direction Z is not restricted, and the spring constant of the second leaf spring parts 12, 42, and 52, a spring constant lower than the spring constants of the first leaf spring part 11 and the second leaf spring parts 12, 42, and 52 respectively, and the spring constant of the first leaf spring part 11 appear in this order.

[0078] In addition, within the scope not departing from the gist of the present invention, it is possible to appropriately replace the constituent elements in the above-described embodiment with well-known constituent elements, and the above-described embodiment and modification examples may be appropriately combined.

Explanation of Reference Numerals

[0079] 1, 2, 3, 4, 5 Leaf spring devices 10 Power conversion device 11 First leaf spring part 12, 42, 52 Second leaf spring parts 13, 23 Restricting parts 14 Seat plate 15 Connecting part 16, 36 Holding members 17, 47 Connecting members 101 Semiconductor laminate unit (second pressed body) 102 Housing (first pressed body) 103 Semiconductor module 104 Cooling pipe Z First direction

Claims

1. A leaf spring device comprising a first leaf spring portion and a second leaf spring portion that are stacked in the first direction between a first pressed body and a second pressed body that face each other in the first direction, wherein the first leaf spring portion supported by the first pressed body and the second leaf spring portion supported by the second pressed body are curved so as to have a top portion that projects in the first direction, the first leaf spring portion has a lower spring constant in the first direction than the second leaf spring portion, the pushing load in the first direction applied to this leaf spring device to push the first leaf spring portion into deformation in the first direction, is greater than the pushing load in the first direction applied to this leaf spring device to push the second leaf spring portion into deformation in the first direction. A leaf spring device.

2. The leaf spring device according to claim 1, further comprising a holding member that holds the first leaf spring portion in a state where a pushing load for pushing the first leaf spring portion in the first direction is applied.

3. The leaf spring device according to claim 2, further comprising a restricting portion that restricts further pushing deformation of the second leaf spring portion in the first direction when the second leaf spring portion is pushed in the first direction.

4. When the restricting portion restricts further pushing deformation of the second leaf spring portion in the first direction, the pushing load in the first direction applied to this leaf spring device, is equal to or greater than the pushing load in the first direction applied to this leaf spring device when the first leaf spring portion begins to be pushed into deformation in the first direction. The leaf spring device according to claim 3.

5. The first leaf spring portion and the second leaf spring portion are curved in opposite directions to each other in the first direction, and are provided such that the top portions overlap each other in the first direction, and the restricting portion is provided between the top portion of the second leaf spring portion and the second pressed body. The leaf spring device according to claim 3 or 4.

6. The holding member comprises a seat plate provided between the first leaf spring portion and the first pressed body, and a connecting portion that connects the restricting portion and the seat plate in the first direction. The leaf spring device according to any one of claims 3 to 5.

7. The leaf spring device according to any one of claims 1 to 6, further comprising a connecting member that connects the first leaf spring portion and the second leaf spring portion to each other in the first direction.

8. A power conversion device in which a semiconductor stacked unit and the leaf spring device according to any one of claims 1 to 7 are housed in a housing in a state of being arranged in the first direction. The semiconductor stack unit includes at least one semiconductor module and at least one cooling pipe arranged alternately in the first direction. A power conversion device in which either one of the first pressed body and the second pressed body serves as the housing, and the other serves as the semiconductor stack unit.

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