JP2005074795A - Joining structure of resin case and fluid pump device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid pump device which can reduce breakage caused by the change in the internal pressure of a pump chamber. <P>SOLUTION: The pump chamber P of the fluid pump device is formed by welding a motor side welding surface 31 formed in the opening side end part K1 of a motor side resin case 1 and a pump side welding surface 32 formed in the opening side end part K2 of a pump side resin case 3. The thicknesses L3 and L4 of a motor side flange part 33 and a pump side flange part 38 where the welding surfaces 31 and 32 are formed are set up to be smaller than the width L5 of the motor side welding surface 31 and the pump side welding surface 32. By the warping of the motor side flange part 33 and the pump side flange part 38 in relation to the increase of the internal pressure of pump chamber P, stress produced in the outside part in a welding part is made compressive stress. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a resin case joining structure in which a fluid is accommodated and an internal pressure changes, and a fluid pump device.

  2. Description of the Related Art Conventionally, some fluid pump devices include a motor-side case that houses a motor main body and a pump-side case that forms a pump chamber. The inside of the motor side case is partitioned by a partition wall, and a motor housing portion for housing the motor body and a pump chamber constituting portion constituting a part of the pump chamber are formed therein. The opening side end of the pump side case is fixed to the opening side end of the motor side case on the side of the pump chamber constituting portion, so that the pump chamber constituting portion of the motor side case and the inner surface of the pump side case A chamber is formed. In such a fluid pump device, for example, the rotation shaft of the motor main body in the motor housing and the impeller in the pump chamber are coupled by a coupling magnet in a non-contact manner (with the partition wall sandwiched).

In such a fluid pump device, the motor side case and the pump side case are both made of resin, and the welding surfaces formed at the end portions on the opening side are welded (for example, orbital welding) and fixed. There is. Further, as such a joint structure, a flange portion is formed at each opening side end portion, a protrusion portion is formed at least at one flange portion, and a member (the other protrusion portion) whose welding surface at the tip of the protrusion portion is opposed to each other. Alternatively, there is one that is welded and fixed to a flange portion where no protruding portion is formed (for example, see Patent Document 1).
JP 2002-283455 A (FIGS. 1 and 9)

  By the way, in the above fluid pump apparatus, the internal pressure in the pump chamber (resin case) in which the fluid is accommodated changes. Further, as schematically shown in FIG. 6, the thickness L1 of the flange portion 51 is larger than the width L2 (inward and outward directions) of the welding surfaces 52 and 53.

  In such a configuration, the rigidity of the flange portion 51 (opening side end portion) is high, and the pulling force in the direction of separating from the welding surfaces 52 and 53 with respect to the increase in internal pressure in the pump chamber 54 (resin case) is high. Therefore, the stress generated in the welded portions (welded surfaces 52 and 53) is substantially equal in the inner portion and the outer portion (relative to the pump chamber 54), and both become tensile stresses. The stress generated in the welded portions (welded surfaces 52 and 53) may change indefinitely according to external vibration, deformation based on a temperature difference between the motor side case 55 and the pump side case 56, or the like. Therefore, the maximum tensile stress is generated in the inner portion of the welded portion, and the maximum tensile stress is generated in the outer portion. The welded portions (welded surfaces 52 and 53) are strong against compressive stress but weak against tensile stress. For these reasons, there has been a risk of destruction from the inside and outside of the welded portion (welding surfaces 52, 53), and the pump chamber 53 may be destroyed (communication with the outside).

  In particular, in a vehicle adopting an idle stop system, an electric fluid pump device that is provided with a mechanical pump that is driven based on engine driving and circulates cooling water, and that circulates cooling water during idle stop (when the engine is not driven). The internal pressure of the pump chamber becomes positive and negative when the engine is driven and when idling is stopped, and the change in the internal pressure increases. Further, in this fluid pump device for circulating cooling water during idle stop, the number (frequency) of changes in the internal pressure is the number of times corresponding to the number of stops and movements of the vehicle, and is extremely large. Therefore, there is a problem that the destruction is likely to occur.

Although it is conceivable to prevent the destruction by thickening the entire motor side case and pump side case (each part), this increases the volume and weight.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a resin case joining structure and a fluid pump device that can reduce breakage due to changes in internal pressure. is there.

  In the first aspect of the invention, the first welding surface formed at the opening side end portion of the resin-made first case and the second welding surface formed at the opening side end portion of the resin-made second case are provided. A resin case joining structure for welding and forming a resin case for containing a fluid, and with respect to an increase in internal pressure in the resin case, at an outer portion of the first and second welding surfaces The opening side end portion was formed so that the generated stress was a compressive stress.

  According to a second aspect of the present invention, in the resin case joining structure according to the first aspect, at least one of the opening-side end portions is formed with an outwardly extending flange portion. At least one of the two welding surfaces is formed in the flange portion, and the thickness of the flange portion is set to a predetermined pulling force in a direction in which the first case and the second case are separated from each other based on an increase in the internal pressure. On the other hand, it was set to a predetermined value at which the flange portion bends.

According to a third aspect of the present invention, in the resin case joining structure according to the second aspect, the thickness of the flange portion is set to be smaller than the width of the first and second welding surfaces.
According to a fourth aspect of the present invention, in the resin case joint structure according to any one of the first to third aspects of the present invention, at least one of the opening-side end portions is provided on the inner side with respect to the increase of the internal pressure. The groove portion was provided so that the outside expanded.

The invention according to claim 5 is a fluid pump device having the resin case joining structure according to any one of claims 1 to 4, wherein the fluid pump device for circulating cooling water at idle stop is summarized. And
(Function)
According to the first aspect of the present invention, the opening of the first and second cases is such that the stress generated in the outer portions of the first and second welding surfaces becomes the compressive stress with respect to the increase of the internal pressure in the resin case. Since the side end portion is formed, occurrence of a large tensile stress in the outer portion is reduced. Therefore, even if breakage occurs from the inside in the welded portions (first and second weld surfaces), breakage from the outside is difficult to occur, and consequently breakage of the resin case (communication with the outside) is reduced.

  According to invention of Claim 2, the thickness of a flange part is set to the predetermined value which a flange part bends with respect to the predetermined | prescribed pulling force of the direction which separates the 1st case and 2nd case based on the raise of internal pressure. Is set. Therefore, the flange portion bends in a direction in which the inner side of the flange portion (from the welded portion) is away from the other member side with respect to a predetermined pulling force in a direction in which the first case and the second case are separated from each other due to the increase in internal pressure. It will be. Thereby, with respect to the increase of the internal pressure in the resin case, the stress generated in the inner portions of the first and second welding surfaces becomes the tensile stress, but the stress generated in the outer portion can be the compressive stress.

  According to a third aspect of the present invention, the flange portion is bent with respect to the predetermined tensile force by setting the thickness of the flange portion to be smaller than the width of the first and second welding surfaces. Set to a predetermined value. If it does in this way, a flange part will bend reliably and the stress which arises in the outer part in the 1st and 2nd welding surface will turn into a compressive stress.

  According to invention of Claim 4, a groove part is provided in the inner side of at least one of the opening side edge parts so that the outer side may expand with respect to the increase in the internal pressure. Therefore, the opening side end portion bends so that the outside of the opening side end portion expands as the internal pressure increases. Thereby, with respect to the increase of the internal pressure in the resin case, the stress generated in the inner portions of the first and second welding surfaces becomes the tensile stress, but the stress generated in the outer portion can be the compressive stress.

  According to the invention described in claim 5, the effect of the invention described in any one of claims 1 to 4 can be obtained in the fluid pump device for circulating cooling water during idle stop. In the fluid pump device for circulating the cooling water during idle stop, the effect is more effective because the change in internal pressure is large and the number of changes is large.

According to this invention of Claims 1-4, the joining structure of the resin-made cases which can reduce the fracture | rupture based on the change of an internal pressure can be provided.
According to the fifth aspect of the present invention, it is possible to provide a fluid pump device that can reduce breakage due to a change in internal pressure.

  Hereinafter, an embodiment in which the present invention is embodied in a fluid pump device for circulating cooling water at idle stop will be described with reference to FIGS. As shown in FIG. 1, the fluid pump device includes a motor side case 1 as a first case, a motor side cover 2, a pump side case 3 as a second case, a motor body 4, and an impeller member 5. Prepare. In the present embodiment, the motor side case 1 and the pump side case 3 constitute a resin case.

  The motor side case 1 is made of resin, and includes a substantially cylindrical cylindrical portion 1a and a partition wall 1b that partitions the inside thereof. The partition wall 1b of the present embodiment includes a disk part 1c extending radially inward from one opening side end K1 of the cylindrical part 1a, and the other opening side of the cylindrical part 1a from the disk part 1c (right side in FIG. 1). ) And a bottom 1e that closes the tip of the small-diameter cylinder 1d. At the center of the bottom portion 1e, a support cylinder portion 1f extending to one opening side (left side in FIG. 1) of the cylindrical portion 1a is erected. The motor-side case 1 is partitioned by a partition wall 1b so that a motor housing portion 1g for housing the motor main body 4 and a pump chamber constituting a part of a pump chamber P described later are included therein. A component 1h is formed.

  The motor main body 4 is accommodated in the motor accommodating portion 1g formed on the other opening side (right side in FIG. 1) of the cylindrical portion 1a, and the motor side cover 2 is disposed on the other opening side end portion of the cylindrical portion 1a. Is fixed. The motor body 4 of the present embodiment is a direct current motor, and includes a yoke 11, a stator magnet 12 fixed to the inner peripheral surface of the yoke 11, and an armature 13 disposed inside the stator magnet 12. The armature 13 has a rotating shaft 14, and one end of the rotating shaft 14 is supported by a bearing 15 fixed to the bottom 1 e of the partition wall 1 b and the other end is fixed to the motor side cover 2. It is supported so that it can rotate. An outer ring magnet 17 that is one of coupling magnets is fixed to one end side of the rotating shaft 14 via a collar. The outer ring magnet 17 includes a disc portion 17a extending radially outward of the rotating shaft 14, a cylindrical portion 1a of the motor-side case 1 extending from the outer edge of the disc portion 17a, and a small-diameter cylindrical portion 1d of the partition wall 1b. The cylinder part 17b arrange | positioned in the clearance gap between.

  The pump side case 3 is fixed to one opening side end K1 of the cylindrical portion 1a in the motor side case 1. The pump side case 3 is made of resin, and has a cylindrical pump cylinder part 3a, an inflow cylinder part 3b extending from one end side (left side in FIG. 1) of the pump cylinder part 3a while reducing the diameter, and a pump cylinder part An outflow cylindrical portion 3c extending outward (in FIG. 1, the back side of the paper surface) is provided to allow communication between the hole formed in the peripheral wall 3a and the outside. And the opening side end K2 of the pump cylinder part 3a in the pump side case 3 is fixed to one opening side end K1 of the cylindrical part 1a in the motor side case 1, whereby the pump chamber constituting part 1h and the pump side A pump chamber P as a resin case is formed by the inner surface of the case 3.

  An impeller member 5 is accommodated in the pump chamber P. The impeller member 5 includes an impeller body 21 and an inner ring magnet 22 that is the other of the coupling magnets. The impeller body 21 includes an impeller portion 21a disposed inside the pump tube portion 3a, and an impeller tube portion 21b disposed from the impeller portion 21a to the pump chamber constituting portion 1h (between the small diameter tube portion 1d and the support tube portion 1f). The cylindrical inner ring magnet 22 is fitted on the outer peripheral surface of the impeller cylinder portion 21b. The impeller member 5 is rotatably supported via a bearing 24 by a support shaft 23 supported by the support cylinder portion 1f of the inner peripheral surface of the impeller portion 21a. The impeller portion 21a is formed by connecting a plurality of wing portions arranged in an annular shape. When the impeller portion 21a is rotated, the impeller portion 21a draws fluid existing in the axial direction and radiates radially outward.

  The fluid pump device according to the present embodiment is provided with a mechanical pump (which is driven based on engine driving and circulates cooling water) in a vehicle adopting the idle stop system, and is in idle stop ( Cooling water is circulated when the engine is not driven. Specifically, the fluid pump device is for ensuring a heating function in the vehicle compartment at the time of idling stop, and even if the mechanical pump is stopped together with the idling stop, the fluid pump device is driven at the idling stop and is heated (heated). It is for flowing cooling water. That is, in the fluid pump device, the inflow cylinder portion 3b and the outflow cylinder portion 3c are connected to a cooling water pipe communicating with the heater core or the like.

  Here, the opening side end K1 of the cylindrical portion 1a in the motor side case 1 and the opening side end K2 of the pump cylinder portion 3a in the pump side case 3 are a motor side welding surface 31 as a first welding surface, The pump side welding surface 32 as the second welding surface is fixed by welding (in this embodiment, orbital welding) (see FIGS. 2 and 3).

  Specifically, as shown in FIG. 3, a motor side flange portion 33 extending outward in the radial direction is formed at the opening side end K <b> 1 of the motor side case 1. A motor-side welding projection 34 that slightly projects in the axial direction (side on which the pump-side case 3 is disposed) is formed in an annular shape at the radial intermediate portion of the motor-side flange portion 33, and the tip surface thereof is The motor side welding surface 31 is used. Further, on the radially outer side of the motor-side flange portion 33, an outer protruding wall 35 that protrudes larger than the motor-side welding protruding portion 34 in the axial direction (side on which the pump-side case 3 is disposed) is formed in an annular shape. Yes. Further, on the radially inner side of the motor side flange portion 33, an inner protruding wall 36 that protrudes larger than the motor side welding protruding portion 34 in the axial direction (side on which the pump side case 3 is disposed) is formed in an annular shape. Yes. In addition, an innermost protruding wall 37 that protrudes further in the axial direction (side on which the pump-side case 3 is disposed) in the axial direction (side on which the pump-side case 3 is disposed) is annular at the opening end K1 on the radially inner side of the inner protruding wall 36. Is formed.

  On the other hand, as shown in FIG. 3, a pump side flange portion 38 extending outward in the radial direction is formed at the opening side end portion K <b> 2 of the pump side case 3. In the present embodiment, the pump-side flange portion 38 extends radially outward through a step portion 39 that is partially formed in the circumferential direction. A pump-side welding projection 40 projecting in the axial direction (side on which the motor-side case 1 is disposed) is formed in an annular shape in the radial intermediate portion of the pump-side flange portion 38, and the tip surface thereof is the pump. A side welding surface 32 is provided.

  Thicknesses L3 and L4 (see FIGS. 2 and 3) of the motor-side flange portion 33 and the pump-side flange portion 38 (see FIGS. 2 and 3) are based on the increase in the internal pressure in the pump chamber P. It is set to a predetermined value at which it bends with respect to a predetermined pulling force in a direction in which the side case 3 is pulled away. The predetermined pulling force is a value corresponding to an internal pressure that changes during use of the fluid pump device of the present embodiment, and the predetermined value is at least when the internal pressure during use is maximum. The flange portion 33 and the pump side flange portion 38 are bent (see FIG. 4). In the present embodiment, the thicknesses L3 and L4 (in the axial direction) of the motor-side flange portion 33 and the pump-side flange portion 38 are the same as those of the motor-side welding surface 31 and the pump-side welding surface 32 (in the radial direction). ) By being set smaller than the width L5, the predetermined value is obtained.

  Then, the pump side welding surface 32 is brought into pressure contact with the motor side welding surface 31, and in that state (the motor side case 1 or the pump side case 3) is vibrated so as to draw a minute circle in the horizontal direction. Thereby, the resin of the pump side welding surface 32 and the motor side welding surface 31 (the pump side welding projection 40 and the motor side welding projection 34) is melted, and both members are welded (see FIG. 2). At this time, the outer projecting wall 35, the inner projecting wall 36, and the innermost projecting wall 37 are close to an opposing member (pump side flange portion 38, etc.) and have a passage (internal and external) that leads to the welded portion. Block. Further, the outer projecting wall 35, the inner projecting wall 36, and the innermost projecting wall 37 are welded as described above, as shown in FIG. It is set to have a gap Z. The predetermined gap Z is an interval that can prevent burrs from being scattered during welding and allows the motor side flange portion 33 and the pump side flange portion 38 to bend (see FIG. 4).

  In the fluid pump device configured as described above, for example, when the vehicle is stopped by a signal or the like, idle stop is performed and the mechanical pump is stopped, power is supplied to the motor body 4 and the armature 13 is rotationally driven. Then, the outer ring magnet 17 is rotated together with the rotating shaft 14, and the impeller member 5 is rotated by the magnetic action between the outer ring magnet 17 that is a coupling magnet and the inner ring magnet 22. Then, the cooling water (fluid) on the inflow cylinder part 3b side is drawn into the pump chamber P and discharged to the outflow cylinder part 3c side. Therefore, the (cooled) cooling water is supplied to the heater core, and the heating function in the vehicle compartment is ensured even during idling stop.

Next, characteristic effects of the above embodiment will be described below.
(1) In the fluid pump device, the internal pressure in the pump chamber P changes. Then, a predetermined pulling force F1 in a direction in which the motor side case 1 (opening side end K1) and the pump side case 3 (opening side end K2) are separated from each other based on the increase in internal pressure in the pump chamber P (see FIG. 4). As a result, the motor side flange portion 33 and the pump side flange portion 38 bend in a direction in which the inner side is away from the other member side from the welded portion and in a direction in which the outer side is closer to the other member. As a result, a tensile force F2 is applied to the inner portion of the welding portion (the motor-side welding surface 31 and the pump-side welding surface 32), and a compressive force F3 is applied to the outer portion. Therefore, the stress generated in the inner portion of the welded portion (the motor-side weld surface 31 and the pump-side weld surface 32) is a tensile stress, but the stress generated in the outer portion is a compressive stress. As a result, for example, even if the stress changes somewhat according to external vibration or deformation based on a temperature difference, the occurrence of a large tensile stress in the outer portion of the welded portion is reduced. Therefore, even if destruction occurs from the inside in the welded portion, destruction from the outside hardly occurs, and the destruction of the pump chamber P (communication with the outside) is reduced.

  (2) In the present embodiment, the thicknesses L3 and L4 (in the axial direction) of the motor-side flange portion 33 and the pump-side flange portion 38 are the same as those of the motor-side welding surface 31 and the pump-side welding surface 32 (in the radial direction). ) By setting the width smaller than the width L5, the motor-side flange portion 33 and the pump-side flange portion 38 are set to a predetermined value that bends with respect to a predetermined pulling force. If it does in this way, the motor side flange part 33 and the pump side flange part 38 will bend reliably, and the stress which arises in the outer part in the welding part (the motor side welding surface 31 and the pump side welding surface 32) will turn into a compressive stress.

  (3) The outer projecting wall 35, the inner projecting wall 36, and the innermost projecting wall 37 are welded to each other so as to form a predetermined gap Z with a facing member (pump side flange portion 38, etc.) as shown in FIG. Have. Therefore, the outer projecting wall 35, the inner projecting wall 36, and the innermost projecting wall 37 substantially block the (inner and outer) path leading to the welded portion, thereby preventing burrs from being scattered at the time of welding. The bending of the flange portion 33 and the pump side flange portion 38 (see FIG. 4) is allowed.

  (4) The fluid pump device according to the present embodiment is for circulating the cooling water at the time of idling stop. This is because the change of the internal pressure in the pump chamber P is large and the number of changes is large. ) Becomes more effective.

The above embodiment may be modified as follows.
In the above embodiment, the motor-side flange portion 33 and the pump-side flange portion 38 are formed at the opening-side end portions K1 and K2, and the portions are bent with respect to the increase in internal pressure, so that the outer portion of the welded portion The generated stress is the compressive stress. However, the shape of the opening-side end portions K1 and K2 may be changed if the stress generated in the outer portion of the welded portion with respect to the increase in internal pressure becomes the compressive stress.

  For example, as shown in FIG. That is, as shown in FIG. 5, a groove 42 is formed on the inner side (in the radial direction) of the opening side end K3 of the pump side case 41 so that the outer side (in the radial direction) expands in response to the increase in the internal pressure. ing. Therefore, the opening side end portion K3 bends so that the outside of the opening side end portion K3 expands (outward in the radial direction) as the internal pressure increases. Thereby, the stress generated in the inner portion of the welded portion (the motor-side weld surface 43 and the pump-side weld surface 44) becomes a tensile stress with respect to the increase in the internal pressure in the pump chamber P, but the stress generated in the outer portion is a compressive stress. It becomes. This reduces the occurrence of large tensile stress in the outer portion of the welded portion. Therefore, even if destruction occurs from the inside in the welded portion, destruction from the outside hardly occurs, and the destruction of the pump chamber P (communication with the outside) is reduced. In this example (FIG. 5), the inner protruding wall 46 of the opening side end K4 of the motor side case 45 is formed to have a predetermined gap Z with the inner peripheral surface of the opening side end K3. Even in this case, the inner projecting wall 46 substantially closes the (inner) path leading to the welded portion, preventing burrs from being scattered during welding and allowing the opening side end K3 to bend. The

  In the above embodiment, the thicknesses L3 and L4 of the motor side flange portion 33 and the pump side flange portion 38 are set to be smaller than the width L5 of the motor side welding surface 31 and the pump side welding surface 32. As long as at least one of the side flange portion 33 and the pump side flange portion 38 is set to bend with respect to the increase in the internal pressure, the thicknesses L3 and L4 may be changed.

  The outer projecting wall 35, the inner projecting wall 36, and the innermost projecting wall 37 of the above embodiment are projected from the opening side end K1 side of the motor side case 1, but the opening side end of the pump side case 3 You may change so that it may protrude from K2 side, and it is good also as a structure which does not form them.

  The opening side end K1 and the opening side end K2 of the above embodiment are fixed by orbital welding of the motor side welding surface 31 and the pump side welding surface 32, but other welding is performed. May be fixed.

  In the embodiment described above, the fluid pump device for circulating the cooling water at the time of idling stop is embodied. However, it may be changed to a fluid pump device used for other applications. Moreover, as long as the fluid is accommodated in the inside and the internal pressure changes (is), it may be embodied in another resin case or another device provided with the resin case.

The technical idea that can be grasped from the above embodiments will be described below together with the effects thereof.
(A) In the resin case joining structure according to any one of claims 2 to 4, at least one of the inner side and the outer side of the first and second welding surfaces in at least one of the opening side end portions. Has a protruding wall that protrudes toward the facing member and substantially closes the path leading to the welded portion, and the protruding wall is set to have a predetermined gap with the facing member. Bonding structure of resin case. If it does in this way, the path | route which leads to a welding part in a protrusion wall will be obstruct | occluded substantially, and the scattering of the burr | flash which generate | occur | produces at the time of welding can be prevented. Moreover, since the protruding wall is set to have a predetermined gap with the opposing member, the opening side end portion (flange portion or the like) is allowed to bend.

  (B) A fluid pump device comprising the resin case joining structure according to any one of claims 1 to 4. If it does in this way, in the fluid pump device, the effect of the invention given in any 1 paragraph of Claims 1 thru / or 4 can be acquired.

The principal part sectional drawing of the fluid pump apparatus in this Embodiment. Sectional drawing which shows the opening side edge part in this Embodiment. The exploded sectional view showing the opening side end in this embodiment. Explanatory drawing for demonstrating the opening side edge part in this Embodiment. Sectional drawing which shows the opening side edge part in another example. Sectional drawing which shows the opening side edge part in a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,45 ... Motor side case (1st case), 3,41 ... Pump side case (2nd case), 31, 43 ... Motor side welding surface (1st welding surface), 32, 44 ... Pump side welding surface ( (Second welding surface), 33 ... motor side flange portion (flange portion), 38 ... pump side flange portion (flange portion), 42 ... groove portion, K1 to K4 ... opening side end portions, L3, L4 ... (of the flange portion) Thickness, width of L5 (first and second welding surfaces).

Claims (5)

In order to accommodate the fluid by welding the first welding surface formed at the opening side end portion of the resin-made first case and the second welding surface formed at the opening side end portion of the resin-made second case. The resin case joining structure that forms the resin case of
In the resin case, the opening-side end portion is formed so that a stress generated in an outer portion of the first and second welding surfaces becomes a compressive stress with respect to an increase in internal pressure in the resin case. Joining structure. In the joining structure of the resin case according to claim 1,
A flange portion extending outward is formed on at least one of the opening side end portions,
At least one of the first and second welding surfaces is formed on the flange portion,
The thickness of the flange portion is set to a predetermined value at which the flange portion bends with respect to a predetermined pulling force in a direction in which the first case and the second case are separated from each other based on an increase in the internal pressure. The resin case joint structure. In the joining structure of the resin case according to claim 2,
The resin case bonding structure according to claim 1, wherein a thickness of the flange portion is set smaller than a width of the first and second welding surfaces. In the joining structure of the resin cases according to any one of claims 1 to 3,
A resin case joining structure characterized in that a groove is provided on the inner side of at least one of the opening-side end portions so that the outer side expands as the internal pressure increases.   A fluid pump device comprising the resin case joining structure according to any one of claims 1 to 4, wherein the fluid pump device is used for circulating cooling water during idle stop.

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