JPH0690506A - Cooling device for semiconductor control element for electric motorcar - Google Patents

Abstract

PURPOSE:To provide a cooling device for semiconductor control elements for an electric motorcar which is easily loaded on a vehicle. CONSTITUTION:A first circulating oil passage 70 and a second circulating oil passage 72 for returning lubricating oil 40 in a housing 16, which is discharged out of an oil pump 68, into the housing 16 through a cooler 52, to which semiconductor control elements 50 are fixed, are provided while the housing 16 of a transaxle is provided with a comparatively large heat capacity and is arranged at a place directly hit by car-speed air whereby semiconductor control elements 50 are cooled optimally. Accordingly, a radiator for cooling the lubricating oil 40 circulated to cool the semiconductor control elements 50 becomes unnecessary whereby comparatively limited loading position on a vehicle, since a comparatively large shape radiator is required to be arranged at a position capable of being contacted with outside air so as to be favorable to the heat dissipation of the same, and the provision of a fan for increasing the heat radiating effect of the radiator are eliminated respectively and loading it on the vehicle is facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for semiconductor control elements for electric vehicles.

[0002]

2. Description of the Related Art A transmission for changing the rotation of an electric motor,
There is known an electric vehicle having a trunk axle having a housing that houses the transmission and a housing in which a lubricating oil for lubricating the inside of the transmission is stored. In such an electric vehicle, when the electric motor is an AC motor, the rotation is controlled by an inverter that controls the drive frequency, and when the electric motor is a DC motor, the rotation is controlled by a current control unit that controls the drive current. Controlled. A semiconductor control element for electric power such as a thyristor, a triac, a power transistor for controlling a relatively large current is used in the inverter or the current control unit, and the heat loss of the semiconductor control element for electric power is effectively reduced. A cooling device is provided for discharge to the. For example, a cooling device for a semiconductor control element for an electric vehicle, which is described in Japanese Patent Laid-Open No. 2-151561, is an example of a type of cooling by natural convection.

However, a cooling device for a semiconductor control element for an electric vehicle of the type which is cooled by natural convection as described above,
Since the efficiency of heat transfer from the cooling fins to the air is low and the volume of the cooling fins for air cooling is large, the mountability on the vehicle is impaired.

On the other hand, by circulating a fluid between the radiator and the cooling member to which the semiconductor control element is fixed, that is, the heat exchanger, heat is dissipated from the radiator and the cooling member to which the semiconductor control element is fixed. Cooling type cooling devices have been proposed. According to this, the efficiency of heat transfer from the cooling member to the fluid is improved, and the volume ratio of the cooling device is improved.

[0005]

However, in the above-described conventional cooling device, not only the pump for circulating the fluid but also the radiator for cooling the fluid containing the heat from the cooling member is relatively large and advantageous for heat radiation. Since it is necessary to place the radiator at a position where it can contact the outside air, the mounting position in the vehicle is relatively limited, and it is necessary to install a fan to enhance the heat radiation effect of the radiator. was there.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a cooling device for a semiconductor control element for an electric vehicle, which can be easily mounted on a vehicle.

[0007]

The object of the present invention to achieve the above object is to provide a transmission for changing the rotation of an electric motor, a housing for the transmission, and a lubrication for the transmission. In an electric vehicle equipped with a transaxle having a housing in which the lubricating oil is stored, a cooling device for cooling a semiconductor control element for controlling the rotation of the electric motor, comprising: An oil pump for pressure-feeding, (b) a cooler in which the semiconductor current control element is fixedly mounted in order to absorb heat generated in the semiconductor control element, (c) lubricating oil discharged from the oil pump, A circulating oil passage that passes through a cooler and returns to the inside of the housing.

[0008]

According to this structure, the lubricating oil in the housing discharged from the oil pump is returned to the inside of the housing through the cooler in which the semiconductor control element is fixed. The heat generated in the semiconductor control element to be controlled is carried into the transaxle via the lubricating oil. Since the housing of the transaxle is relatively heavy because it is made of cast iron or aluminum alloy to accommodate the transmission, etc.,
Since it has a relatively large heat capacity and is provided at a position where it is directly exposed to the vehicle speed air, the lubricating oil returned to the transaxle is suitably cooled by its housing, etc. By doing so, the semiconductor control element is suitably cooled.

[0009]

Therefore, the radiator for cooling the lubricating oil, which is a circulating fluid for cooling the semiconductor control element, is not required. Therefore, there is a disadvantage caused by mounting the radiator, that is, a radiator having a relatively large shape. Since it is necessary to arrange the vehicle in a position where it can come into contact with the outside air in order to favor heat dissipation, the mounting position in the vehicle is relatively limited, and the provision of a fan for enhancing the heat dissipation effect of the radiator is eliminated. Therefore, there is provided a cooling device for a semiconductor control element for an electric vehicle that can be easily mounted on a vehicle.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a transaxle 1 of an electric vehicle.
0 shows the outline of the configuration of No. 0, and the rotation output of the electric motor 12 for driving the electric vehicle is reduced by the reduction gear 14 and then transmitted to the drive wheels via a propeller shaft, a differential gear device, and an axle (not shown). It is being transmitted.

An electric motor 12 is integrally fixed to the transaxle 10, and the transaxle 10 has a housing 16 for accommodating a speed reducer 14. The housing 16 is formed by die casting of cast iron or aluminum alloy, and has a relatively large weight of, for example, about 30 kg,
Its heat capacity is relatively large.

The speed reducer 14 is connected to the output shaft 18 of the electric motor 12 via a joint 20 and has an input shaft 24 to which a small diameter first gear 22 is fixedly mounted, and meshes with the first gear 22. An intermediate shaft 30 having a second gear 26 having a larger diameter than that of the third gear 28 and a third gear 28 having a relatively smaller diameter fixed thereto, and a fourth gear 3 that meshes with the third gear 28 and has a larger diameter than that.
2 is fixed to the output shaft 34. As a result, the rotation output of the electric motor 12 is decelerated according to the gear ratio based on the gear ratio between the first gear 22 and the second gear 26 and the gear ratio between the third gear 28 and the fourth gear 32. Is output from the output shaft 34. The input shaft 24,
The intermediate shaft 30 and the output shaft 34 are rotatably supported by the housing 16 via bearings 36.

Lubricating oil 40 for lubricating the meshing portions of the gears is stored in a housing chamber 38 for housing the speed reducer 14 in the housing 16. In this embodiment, the lubricating oil 40 is also used to cool the semiconductor control element 50 described later.

In FIG. 2, the electric vehicle is provided with a drive control device 48 for controlling the rotation of the electric motor 12. The drive control device 48 is connected between a power source (not shown) such as a storage battery and the electric motor 12, and a drive current corresponding to an acceleration operation amount of an accelerator pedal (not shown) in order to obtain a driving force corresponding to the intention of the driver. Is supplied to the electric motor 12. The drive control device 48
Is a semiconductor control element 50 for electric power composed of one or a plurality of thyristors for controlling the drive frequency or drive current, and the semiconductor control element 50 for dissipating heat loss generated in the semiconductor control element 50. The device 50 is provided with a cooler (heat exchanger) 52 fixedly installed and an electronic circuit 54 for controlling the operation of the semiconductor control device 50. Since the semiconductor control element 50 controls a relatively large current, it is necessary to effectively dissipate the heat loss generated inside the semiconductor control element 50. Therefore, the cooler 52 is provided.

The cooler 52 is made of a material having a high thermal conductivity such as aluminum, and has a fluid chamber 60 communicating with the upstream port 56 and the downstream port 58, and the fluid chamber 6 thereof.
It is provided with a large number of protrusions 62 that protrude from the inner wall surface of No. 0 to improve heat exchange efficiency.

The housing 16 is provided with an outflow port 64 for letting out the lubricating oil 40 and an inflow port 66 for letting in the lubricating oil 40. The oil pump 6 is provided between the inflow port 64 and the upstream port 56 of the cooler 52.
8 is provided by the first circulating oil passage 70, and the downstream port 58 and the outflow port 66 of the cooler 52 are connected by the second circulating oil passage 72, thereby forming a closed circuit. There is.

The oil pump 68 is an electric pump including a small electric motor, and is the accommodation chamber 3 of the housing 16.
In order to pump the lubricating oil 40 that has recirculated into 8 and stored therein, it is rotationally driven by a drive current supplied from, for example, a pump drive control circuit 74. Pump drive control circuit 7
4 constantly drives the oil pump 68 while an ignition key (not shown) is being operated, or drives the oil pump 68 while the ignition key is being operated and the electric motor 12 is being driven.

As described above, according to this embodiment, the lubricating oil 4 in the housing 16 discharged from the oil pump 68 is used.
By providing the first circulating oil passage 70 and the second circulating oil passage 72 for returning 0 to the inside of the housing 16 through the cooler 52 in which the semiconductor control element 50 is fixedly provided, the electric motor 1
The heat generated in the semiconductor control element 50 that controls 2 is carried into the transaxle 10 via the lubricating oil 40. The housing 16 of the transaxle 10 has a relatively large heat capacity because it is made of cast iron or an aluminum alloy to accommodate the speed reducer 14 and thus has a relatively large heat capacity. Since the lubricating oil 40 returned to the transaxle 10 is suitably cooled by the housing 16 because it is provided at the contact position, the semiconductor control element 50 is suitably cooled by circulating the lubricating oil 40. .

Therefore, since a radiator for cooling the lubricating oil 40 circulating for cooling the semiconductor control element 50 is not required, a disadvantage caused by mounting the radiator, that is, a radiator having a relatively large shape is used for heat radiation. Since the mounting position in the vehicle is comparatively limited because it is necessary to arrange it in a position where it can contact the outside air in an advantageous manner, and the provision of the fan for enhancing the heat radiation effect of the radiator is eliminated, respectively, A cooling device for a semiconductor control element for an electric vehicle, which can be easily mounted on an electric vehicle, is provided.

In an electric vehicle, generally, the energy density of the battery is low and the cruising distance per charge is short, but according to the present embodiment, the oil temperature of the lubricating oil 40 is generated by the heat generated from the semiconductor control element 50. The transmission efficiency of the speed reducer 14 is suitably increased particularly in the operation in a cold region, so that the cruising range of the electric vehicle is increased and the power performance is enhanced. That is, since the torque transmission efficiency of the speed reducer 14 has the characteristics shown in FIG. 3, when traveling in cold regions, the transmission efficiency of the speed reducer 14 increases from about 80% to about 98% as the oil temperature increases. It can be greatly increased.

Although the embodiment of the present invention has been described above with reference to the drawings, the present invention can be applied to other aspects.

For example, the housing 16 of the above-described embodiment.
The speed reducer 14 having a constant reduction ratio was housed therein,
It does not matter even if the multi-stage transmission that shifts in multiple stages is housed. Further, a differential gear device may be further housed in the housing 16.

Further, although the oil pump 68 of the above-described embodiment is provided in the first circulating oil passage 70, the second circulating oil passage 7
2 and the housing 16 may be provided.

Further, the pump drive control circuit 74 for driving the oil pump 68, the oil pump 6 according to the load (driving current) of the electric motor 12 and the temperature of the lubricating oil 40.
The rotation of 8 may be increased to increase the flow rate, or the oil pump 68 may be continuously rotationally driven for a fixed time after the electric motor 12 is stopped in addition to the operation of the electric motor 12.

The oil pump 68 is the electric motor 1
It may be mechanically connected to the motor 2 and rotationally driven by the electric motor 12.

Further, a part of the hydraulic oil discharged from the oil pump 68 of this embodiment is pressure-fed to the gears and bearings of the speed reducer 14 for lubrication of the gears and bearings thereof via an oil passage (not shown). Good.

The above description is merely an embodiment of the present invention, and the present invention can be variously modified without departing from the gist thereof.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a transaxle of the present invention.

FIG. 2 is a diagram illustrating a configuration of a cooling device for a power semiconductor control element including the transaxle of FIG.

FIG. 3 is a characteristic diagram showing a relationship between oil temperature and torque transmission efficiency in the speed reducer of the embodiment of FIG.

[Explanation of symbols]

 10: Transaxle 12: Electric motor 14: Reduction gear 16: Housing 40: Lubricating oil 50: Semiconductor control element 52: Cooler 68: Oil pump 70: First circulating oil passage, 72: Second circulating oil passage (circulating oil Road)

Claims (1)

[Claims] 1. A transmission for shifting the rotation of an electric motor,
A cooling device for cooling a semiconductor control element for controlling rotation of the electric motor in an electric vehicle including a transaxle having a housing for accommodating the transmission and storing a lubricating oil for lubricating the inside of the transmission. And an oil pump for pumping the lubricating oil in the housing, a cooler in which the semiconductor control element is fixed to absorb heat generated in the semiconductor control element, and a cooler discharged from the oil pump. A cooling oil passage for returning lubricating oil to the inside of the housing through the cooler, and a cooling device for a semiconductor control element for an electric vehicle.