Capacitor mounting arrangement in a rotary electrical machine

A rotary electrical machine for a vehicle according to the present invention is provided with a stator, a rotor which is provided facing the stator and which rotates coaxially with the stator, a power module which is connected to the stator, a capacitor which eliminates or reduces switching noise in the power module and has a pressure release valve, a circuit board on which the capacitor is mounted, and a heat sink which encompasses the capacitor, wherein a semi-closed cell foam seal material is provided in contact with the pressure release valve, and the capacitor is fixed to a terminal fixing section of the circuit board, and is also fixed to an inner side of the heat sink by an anti-vibration bond in a portion different from the terminal fixing section.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a rotary electrical machine for a vehicle, wherein a drive unit and an inverter assembly including a power module are integrated and a capacitor having a pressure release valve is mounted.

2. Description of the Related Art

In a power module of a rotary electrical machine for a vehicle, a capacitor is used in order to eliminate or reduce noise generated when a switching element of the power module switches on and off. The capacitor is provided with a pressure release valve in order to prevent increases in the internal pressure due to the generation of gas inside the capacitor as a result of the generation of heat by the current, evaporation of the electrolyte solution, or electrolysis of the electrolyte solution.

In the rotary electrical machine for a vehicle disclosed in Japanese Patent Application Laid-open No. 2015-163046, a capacitor is provided on a seat, with the terminal thereof projecting from the lower surface of a cylindrical shape. Furthermore, the capacitor has a pressure release valve on the upper surface and there is a space above the pressure release valve. In the rotary electrical machine for a vehicle disclosed in Japanese Patent Application Laid-open No. 2015-61408, a capacitor is fixed to a frame, with the terminal thereof projecting from the lower surface of a cylindrical shape. Furthermore, the capacitor has a pressure release valve on the upper surface and there is a space above the pressure release valve.

SUMMARY OF THE INVENTION

However, the rotary electrical machines for a vehicle which are disclosed in Japanese Patent Application Laid-open No. 2015-163046 and Japanese Patent Application Laid-open No. 2015-61408 are subjected to large vibrations which occur in many directions. Therefore, in a capacitor having a certain length, if the capacitor has a single support structure in which only one end of the capacitor is fixed, then a large load is placed on the connected terminal and there is a risk of terminal breakage.

This invention was devised in order to resolve the abovementioned problem, with the object thereof being to obtain a rotary electrical machine for a vehicle in which breakage or disconnection does not occur in the terminal of a capacitor.

The rotary electrical machine for a vehicle according to the present invention is provided with a stator, a rotor which is provided facing the stator and rotates coaxially with the stator, a power module which is connected to the stator, a capacitor which eliminates or reduces switching noise in the power module and has a pressure release valve, a circuit board on which the capacitor is mounted, and a heat sink which encompasses the capacitor, wherein a semi-closed cell foam seal material is provided in contact with the pressure release valve, and the capacitor is fixed to a terminal fixing section of the circuit board, and is also fixed to an inner side of the heat sink by an anti-vibration bond in a portion different from the terminal fixing section.

According to the rotary electrical machine for a vehicle of this invention, the capacitor has a double support structure, and large loads are not liable to be placed on the connected terminal and the fixing portion.

Consequently, breakage or disconnection does not occur in the terminal of the capacitor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the rotary electrical machine for a vehicle according to this invention is described below with reference to the drawings. Portions which are the same or equivalent in the drawings are indicated by the same reference numerals and repeated description thereof is omitted here.

First Embodiment

Below, a rotary electrical machine1for a vehicle according to the first embodiment of this invention is described with reference toFIGS. 1 and 2.

FIG. 1is a cross-sectional diagram of a rotary electrical machine for a vehicle according to the first embodiment of the present invention.FIG. 2is a rear surface diagram of a state where the cover inFIG. 1has been removed.

As illustrated inFIG. 1, the rotary electrical machine1for a vehicle is constituted by a drive unit29and an inverter assembly30.

First, the drive unit29will be described.

As illustrated inFIG. 1, a stator3is provided inside the front bracket4and the rear bracket5. In the stator3, a three-phase stator coil3ais wound about a stator iron core3b. A rotor2is provided on the inner side so as to oppose the stator3. The rotor2rotates coaxially with the stator3and is fixed to the rotary shaft11. The rotary shaft11is supported rotatably on the front bracket4via the bearing7. Furthermore, the rotary shaft11is supported rotatably on the rear bracket5via the bearing8. One end of the rotary shaft11projects from the front bracket4and a pulley12is attached thereto. The pulley12is connected to an internal combustion engine (not illustrated) via a belt (not illustrated).

Furthermore, in the rotor2, a field coil2ais wound about the field core2b. A slip ring13for supplying a field current is provided on the field coil2a. The slip ring13projects to the rear side from the rear bracket5. A brush16awhich supplies current to the slip ring13is provided in sliding contact with the slip ring13. The brush16ais held by a brush holder16. Furthermore, fans20and21for generating a cooling air flow are attached to the end surfaces of the field core2b.

A magnetic pole position detection sensor6which detects the position of rotation of the rotor2and the rotary shaft11is provided between the bearing8and the brush holder16. A sensor rotor6bof the magnetic pole position detection sensor6is attached to the rotary shaft11. A sensor stator6ais provided opposing the sensor rotor6bon the outer side in the radial direction of the rotary shaft11.

The inverter assembly30is fixed to a rear bracket5of the drive unit29on which a connecting board18has been installed. The inverter assembly30and the brush holder16are protected by a cover15. The cover15is attached to the rear bracket5by screws32, in the coupling section15aof the cover15. The case14is provided on the inside of the cover15.

As illustrated inFIG. 2, a regulator module9, a field module10, a control module17, cylindrical capacitors19and a heat sink28are provided in a region peripheral to the region of the case14through which the rotary shaft11is passed. A switching element for supplying armature current during driving, and regulating the armature current during power generation is provided together with peripheral circuitry in the regulator module9. The regulator module9is connected to the stator3. A switching element for controlling the field current is provided together with peripheral circuitry in the field module10. The control module17controls the regulator module9and the field module10. The capacitors19eliminate or reduce switching noise produced by the switching element of the regulator module9. The heat sink28cools the regulator module9, the field module10, the capacitors19and the connector26. The regulator module9constitutes a power module.

As illustrated inFIG. 1, the capacitors19are mounted on a terminal board27, which is a circuit board, provided in the case14. The capacitors19are electrically connected and fixed to the terminal27aof the terminal board27. The outer peripheral portion of the terminal27ais bonded and fixed to the case14, by an anti-vibration bond23a. Furthermore, the heat sink28is integrated with the case14by the anti-vibration bond23a. The terminal27aconstitutes a terminal fixing section.

Pressure release valves19aare provided in the capacitors19on the upper surface which are situated on the opposite side from the terminal27a. The capacitors19are fixed to the inner surface of the heat sink28by another anti-vibration bond23bat the periphery of the pressure release valves19a. In this case, a space31is formed between the capacitors19and the heat sink28, and the space31is not sealed with resin.

A semi-closed cell foam seal material24is provided in contact with the pressure release valves19a. When the semi-closed cell foam seal material24makes contact with the pressure release valves19a, the semi-closed cell foam seal material24may be bonded to either the capacitors19or the heat sink28.

In this way, in the rotary electrical machine1for a vehicle according to the first embodiment, the semi-closed cell foam seal material24is provided in contact with the pressure release valves19a, and the capacitors19are fixed to the terminal27aof the terminal board27. In addition to this, the capacitors19are fixed to the inside of the heat sink28by the anti-vibration bond23b, about the periphery of the pressure release valves19awhich are provided on the upper surface in a portion that is different from the terminal27aand is on the opposite side from the terminal27a. Therefore, the capacitors19have a double support structure, and a large load is not liable to be placed on the connected terminal and the fixing portion. Consequently, breakage or disconnection does not occur in the terminal of the capacitors19.

The capacitors19, together with the terminal board27, are shut off from the outside of the heat sink28, by the heat sink28. Consequently, corrosion due to rainwater or the like received from the outside of the heat sink28, does not occur.

A space31is formed between the capacitors19and the heat sink28. Consequently, even if the pressure release valves19aopen and gas inside the capacitors19leaks out into the heat sink28, increase in the pressure inside the heat sink28is suppressed and it is possible to prevent damage to the heat sink28and the terminal board27.

The semi-closed cell foam seal material24which is bonded to the pressure release valves19aof the capacitors19, is sealed in such a manner that the anti-vibration bond23bdoes not infiltrate into or adhere to the pressure release valves19a. Furthermore, the semi-closed cell foam seal material24has a structure similar to a sponge that contains bubbles, and is a member that deforms readily such that the pressure release valves19aopen if there is an abnormality in the capacitors19. Consequently, the semi-closed cell foam seal material24serves as a shock absorber between the pressure release valves19aand the heat sink28, and protects the inner surface of the heat sink28from damage by the pressure release valves19awhen opened.

Second Embodiment

Next, a rotary electrical machine for a vehicle according to a second embodiment will be described with reference toFIG. 3. In the second embodiment, the shape of the semi-closed cell foam seal material is different from the first embodiment.

FIG. 3is a cross-sectional diagram of capacitors mounting section according to a second embodiment of the invention, and shows a cross-section along line III-III inFIG. 1.

As shown inFIG. 3, a semi-closed cell foam seal material241is bonded to the upper surface of the capacitors19. The semi-closed cell foam seal material241is ring-shaped and contacts the pressure release valves19a. Even with this configuration, the semi-closed cell foam seal material241contacts the pressure release valves19a, and therefore when the pressure release valves19aopen, semi-closed cell foam seal material241deforms readily, and the function thereof as a shock absorber between the pressure release valves19aand the heat sink28is maintained.

Furthermore, since the semi-closed cell foam seal material241is ring-shaped, then it is possible to save resources compared to a case where the seal material is a flat plate shape. Moreover, since the inside portion of the semi-closed cell foam seal material241is a space31, then the volume of the space31between the capacitors19and the heat sink28is increased and a beneficial effect is obtained in that increase in the pressure when the pressure release valves19aopen is suppressed.

Furthermore, as a modification example of the second embodiment, due to the viscosity, etc. of the anti-vibration bond23b, the semi-closed cell foam seal material24does not necessarily have to be configured in an integrated fashion, provided that the semi-closed cell foam seal material24makes contact with the pressure release valves19a.

Third Embodiment

Next, a rotary electrical machine for a vehicle according to a third embodiment will be described with reference toFIG. 4. In the third embodiment, the shape of the heat sink is different from the first embodiment.

FIG. 4is a partial cross-sectional diagram of capacitors mounting section in an inverter assembly of a rotary electrical machine for a vehicle according to the third embodiment of the present invention.

The capacitors19are encompassed by a heat sink281and a terminal board27. The capacitors19are fixed to the terminal27aof the terminal board27. Furthermore, pressure release valves19aare provided in the capacitors19on the upper surface which is situated on the side opposite from the terminal27a. The capacitors19are fixed to the inside of the heat sink281about the periphery of the pressure release valves19a, by the anti-vibration bond23b.

A semi-closed cell foam seal material24is provided in contact with the pressure release valves19a. An air hole281awhich passes through the heat sink281is formed in the portion of the heat sink281that opposes the semi-closed cell foam seal material24.

In this way, the capacitors19are fixed to the terminal27aand the heat sink281, and therefore has a double support structure and large loads are not liable to be placed on the connected terminal and the fixing portion. Consequently, breakage or disconnection does not occur in the terminal of the capacitors19.

Furthermore, when the pressure release valves19aof the capacitors19open, the internal pressure of the heat sink281which encompasses the capacitors19increases momentarily, and there is a risk of damage to the circuit components which are provided in the heat sink281and the terminal board27. However, if an air hole281ais provided in the heat sink281in this way, it is possible to suppress increase in the internal pressure of the heat sink281, and the heat sink281and circuit components are not damaged.

Furthermore, the air hole281ais closed by the semi-closed cell foam seal material24, and therefore foreign matter does not enter readily inside the heat sink281.

In the first to third embodiments, the anti-vibration bond23bmay have thermal conductivity. By adopting this configuration, the heat generated by the capacitors19becomes readily transmitted to the heat sink28or281, and therefore the capacitors19are cooled rapidly and the life of the capacitors19is improved.