JP4447410B2 - Rotor cooling device for motor for electric vehicle - Google Patents

Description

  The present invention relates to a liquid-cooled rotor cooling device that includes a motor as a vehicle drive source and circulates a coolant in a case that houses the motor.

  2. Description of the Related Art In recent years, vehicles equipped with motors are known as vehicle drive sources in place of or in combination with internal combustion engines. Some of such vehicles include a device for supplying a coolant such as oil to the motor in order to suppress a temperature rise of the motor when the motor is driven or to lubricate a sliding portion of the motor. .

  For example, Patent Document 1 includes a mechanical oil pump that operates by receiving the rotation of a traveling motor via a torque transmission system, so that the rotational speed of the torque transmission system is high, such as during traveling of an electric vehicle. Then, a technique for supplying a sufficient amount of oil to a lubricating circuit that lubricates the torque transmission system has been proposed.

In Patent Document 2, a transmission mechanism that transmits the power of the motor to the wheels is provided with a rotating member, and oil pumped up by the rotation of the rotating member is guided to the upper side of the case that houses the motor and the transmission mechanism. There has been proposed a technique that includes an oil wall and a separation wall member that prevents oil that is scraped and connected to the oil guide wall from being leaked to the side of the oil guide wall. According to this technique, the oil scraped up by the rotating member of the transmission mechanism can be prevented from escaping to the side of the oil guiding wall by the separation wall member fixed to the introduction wall by leakage prevention.
Japanese Patent No. 3235208 JP-A-11-98616

  By the way, a motor mounted as a drive source in a vehicle is driven at various rotational speeds according to the state of the vehicle (for example, when stopped or when traveling at high speed). Therefore, it is important to control the coolant according to the state of the vehicle.

  Accordingly, an object of the present invention is to provide a rotor cooling device for an electric vehicle motor that can appropriately control the liquid level height of the coolant stored in the case in accordance with the rotational speed of the motor. .

  The invention according to claim 1 includes a motor (for example, the motor 1 in the embodiment) as a vehicle drive source, and a coolant (for example, the case 20 in the embodiment) (for example, the case 20 in the embodiment). Applied to a liquid-cooled electric vehicle motor that circulates (cooling oil in the embodiment) and coupled to a drive shaft of the motor (for example, the drive shaft 2 in the embodiment). The coolant is passed through the rotor shaft 4) in the embodiment, and the rotor of the motor (for example, the rotor 3 in the embodiment) is connected to the first opening / closing member (for example, the first valve 33 in the embodiment) and the second An opening / closing member (for example, the second valve 34 in the embodiment) is provided, and the first opening / closing member is in an open state when the rotor is in a stopped state, and the rotor is in a stopped state. From the open state to the closed state until the predetermined first rotational speed is reached, the coolant in the rotor shaft is held, and the second opening / closing member has the rotor larger than the first rotational speed. Before the predetermined second rotational speed is reached, the closed state is changed to the open state, and the coolant in the rotor shaft is released into the case.

  According to the present invention, when the rotor is in a stopped state, the first opening / closing member is in an open state, and the coolant in the rotor shaft is opened in the case, and the coolant stored in the case The liquid level can be increased. Then, the first opening / closing member is changed from the open state to the closed state until the rotor rotates from the stopped state to the first rotational speed, so that the coolant flowing into the rotor shaft is Inflow into the case is blocked and held in the rotor shaft. Along with this, the liquid level of the coolant stored in the case is lower than when the rotor is stopped. Accordingly, it is possible to suppress an increase in the friction of the rotor due to the coolant due to the increase in the rotational speed from the stopped state while ensuring a cooling function for the rotor rotating at the first rotational speed to a certain level or more.

  The second opening / closing member is changed from the closed state to the open state until the rotor reaches the second rotation number higher than the first rotation number, whereby the cooling that has flowed into the rotor shaft. The liquid is partially allowed to flow into the case. Thereby, the pressure increase in a rotor shaft accompanying the further increase in rotation speed can be suppressed. Further, the amount of stirring of the coolant stored in the case increases due to the increase in the rotational speed of the rotor, and the liquid level height of the coolant stored in the case decreases. When the coolant flows into the case from the rotor shaft through the opening / closing member, the liquid level of the coolant stored in the case can be maintained at a certain level or more. Therefore, even if the rotational speed of the rotor fluctuates, it is possible to suppress an increase in friction while maintaining the cooling function by the coolant.

According to a second aspect of the present invention, the first opening / closing member is changed from an open state to a closed state by a centrifugal force generated by rotation of a rotor.
According to this invention, since the centrifugal force also increases or decreases according to the increase or decrease of the rotational speed of the rotor, the open / close state of the first opening / closing member is controlled based on the centrifugal force proportional to the rotational speed, The first opening / closing member can be easily controlled, and the apparatus configuration can be simplified.

The invention according to claim 3 is the invention according to claim 1, wherein the second opening / closing member is changed from the closed state to the open state by the pressure in the rotor.
According to this invention, by controlling the opening / closing state of the second opening / closing member by the pressure of the rotor, the rotor is driven while maintaining the pressure in the rotor properly even when the rotation speed of the rotor fluctuates. can do.

  The invention according to claim 4 is the invention according to claim 1, wherein the rotor has a third opening / closing member whose shape changes depending on temperature (for example, the third valve 35 in the embodiment). And the third opening member opens the cooling liquid in the rotor shaft into the case when the temperature of the cooling liquid in the rotor shaft becomes a predetermined temperature or more.

  According to the present invention, when the temperature of the coolant in the rotor shaft becomes equal to or higher than a predetermined temperature, the coolant in the rotor shaft is opened in the case by the third opening member. Since the liquid level height of the coolant stored in the case can be maintained above a certain level, the cooling effect of the rotor can be increased, and the magnetic force of the magnet provided on the rotor can be maintained above a certain level, The magnet can be protected from high heat.

According to a fifth aspect of the present invention, in the first aspect, the first opening / closing member is provided on a radially outer side of the rotor than the second opening / closing member.
According to this invention, when the first opening / closing member is in the open state, the coolant in the rotor shaft is released into the case from the outside in the radial direction of the rotor, so that it is stored in the case. The liquid level of the coolant can be further increased. Further, since the second opening member is provided on the radially inner side of the rotor with respect to the first opening member, the second opening member is opened before the rotor reaches the second rotational speed. Even when the state is reached, a part of the coolant in the rotor shaft is stored in a portion on the outer peripheral side of the second opening member. Therefore, while maintaining the liquid level height of the coolant stored in the case above a certain level, the liquid level height can be maintained lower than when the first opening member is in the open state, The effect of ensuring the cooling effect can be enhanced while suppressing the friction caused by the coolant.

According to the first aspect of the present invention, even if the rotational speed of the rotor fluctuates, an increase in friction can be suppressed while maintaining the cooling function by the coolant. Further, an increase in pressure in the rotor shaft can be suppressed.
According to the invention which concerns on Claim 2, while controlling the said 1st opening-and-closing member simply, an apparatus structure can be simplified.

According to the invention which concerns on Claim 3, even when the rotation speed of the said rotor fluctuates, a rotor can be driven, maintaining the pressure in a rotor appropriately.
According to the invention which concerns on Claim 4, the cooling effect of the said rotor can be heightened, the magnetic force of the magnet provided in the said rotor can be hold | maintained more than fixed, and the said magnet can be protected from high heat.
According to the invention which concerns on Claim 5, the effect which ensures the cooling effect can be heightened, suppressing the friction by a cooling fluid.

  Hereinafter, a rotor cooling device for an electric vehicle motor according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a case where the present invention is applied to a motor connected to drive wheels of an electric vehicle will be described.

FIG. 1 is a cross-sectional view of an essential part of an electric vehicle motor according to an embodiment of the present invention. As shown in the figure, a motor 1 that is a drive source of a vehicle is accommodated in a case 20 surrounding the whole. Moreover, the cooling oil which acts as a cooling fluid is stored in the lower part in case 20 so that a detail may mention later.
The motor 1 is provided with a drive shaft 2 so as to penetrate the shaft center of the motor 1. The drive shaft 2 is connected to the case 20 via a bearing 15 and is held by the bearing 15 so as to be rotatable around an axis.

The motor 1 includes a rotor 3 and a stator 11 that faces the rotor 3.
The rotor 3 is disposed on the outer peripheral side of the drive shaft 2 and has a rotor shaft 4 formed in a substantially cylindrical shape, and a rotor core 5 that is provided on the outer peripheral side of the rotor shaft 4 and is formed by laminating laminated steel plates. And a plurality of permanent magnets 6 attached to the rotor core 5. The rotor shaft 4 is integrally connected to the drive shaft 2, and the rotor 3 rotates together with the drive shaft 2. A resolver 22 that detects the rotation angle of the rotor 3 is provided on the drive shaft 2 and the inner wall surface of the case 20 facing the drive shaft 2.
On the other hand, the stator 11 includes a stator core 12 formed by laminating laminated steel plates and a winding (coil) 13 wound around the stator core 12. The stator 11 is fixed and held on the inner wall surface of the case 20.

  In the present embodiment, an oil pan 24 that stores cooling oil acting as a coolant is provided so as to be close to the lower portion of the case 20. The oil pan 24 is connected to one end of the flow passage 28 via the strainer 25. On the other hand, the other end of the flow passage 28 is connected to the drive shaft 2. A mechanical oil pump 27 is disposed in the distribution passage 28. By operating the oil pump 27, the cooling oil stored in the oil pan 24 is sent out from the flow passage 28 into the drive shaft 2 through the strainer 25.

The interior of the drive shaft 2 is formed hollow along the axis. The cooling oil supplied from the flow passage 28 flows through the hollow portion of the drive shaft 2. The drive shaft 2 is formed with a communication passage 32 communicating from the hollow portion to the rotor shaft 4 side. The cooling oil flowing through the drive shaft 2 flows into the rotor shaft 4 through the communication path 32.
The rotor shaft 4 is formed with a hollow inside whose outer shape is formed in a substantially cylindrical shape. And this hollow part functions as the storage chamber 31 which stores the cooling oil which flows in from the said communicating path 32. FIG.

A first valve 33 and a third valve 35 are provided on one end face of the rotor shaft 4 (left end face in FIG. 1). A second valve 34 is provided on the other end surface of the rotor shaft 4 (right end surface in FIG. 1).
The first valve 33 is open when the rotor 3 is in a stopped state, and until the rotor 3 rotates from the stopped state to a predetermined first rotational speed N1 (see FIG. 2). From the open state to the closed state, the cooling oil in the rotor shaft 4 is retained. The first valve 33 can be a valve that changes from an open state to a closed state by a centrifugal force generated by the rotation of the rotor 3, that is, a switching valve that uses a centrifugal force.

The second valve 34 changes from a closed state to an open state before the rotor 3 reaches a predetermined second rotational speed N2 (see FIG. 2) greater than the first rotational speed N1, and the cooling oil in the rotor shaft 4 Is opened in the case 20. As the second valve 34, a valve that is changed from a closed state to an open state by the pressure in the rotor 3, for example, a constant pressure release valve can be used.
In the present embodiment, the first valve 33 is provided on the radially outer side of the rotor 3 than the second valve 34. Further, a relief hole 36 is formed on the inner peripheral side of one end surface of the rotor shaft 4, which contributes to suppression of pressure increase in the rotor shaft 4.

The third valve 35 changes its shape depending on the temperature. When the temperature of the cooling oil in the rotor shaft 4 exceeds a predetermined value, the cooling oil in the rotor shaft 4 is transferred into the case 20. To open.
As the third valve 35, a bimetallic valve, that is, a valve that is opened by bonding two types of metal plates having different thermal expansion coefficients and bending due to a temperature rise can be used.

  In addition, a connection passage 26 that is connected to the oil pan 24 is disposed at a lower portion of the side surface of the case 20. The cooling oil stored in the case 20 can be distributed to the oil pan 24 through the connection passage 26. As described above, the motor 1 in the present embodiment is a liquid-cooled motor that circulates cooling oil in the case 20.

FIG. 2 is a graph showing the relationship between the rotor speed and the oil level in the case. As described above, when the rotor 3 is in a stopped state, the first valve 33 is open, and the cooling oil in the rotor shaft 4 is opened in the case 20. As a result, the liquid level of the coolant stored in the case 20 can be increased (height L0 in FIG. 2).
Then, the first valve 33 is changed from the open state to the closed state until the rotor 3 rotates from the stopped state to the first rotation speed N1. As a result, the cooling oil that has flowed into the rotor shaft 4 is blocked from flowing into the case 20 and held in the rotor shaft 4. Along with this, the liquid level of the cooling oil stored in the case 20 is reduced as compared to when the rotor 3 is stopped (height L1 in FIG. 2).

Accordingly, it is possible to suppress an increase in friction of the rotor 3 due to the cooling oil accompanying an increase in the rotational speed from the stopped state while ensuring a cooling function for the rotor 3 that rotates at the first rotational speed N1 to a certain level or more.
The first valve 33 is a valve that is changed from an open state to a closed state by a centrifugal force generated by the rotation of the rotor 3. Accordingly, since the centrifugal force also increases / decreases in accordance with the increase / decrease of the rotational speed of the rotor 3, the first valve 33 is controlled by controlling the open / close state of the first valve 33 based on the centrifugal force proportional to the rotational speed. Can be easily performed, and the apparatus configuration can be simplified.

  Then, the second valve 34 is changed from the closed state to the open state until the rotor 3 reaches the second rotational speed N2 that is larger than the first rotational speed N1, so that the rotor shaft 4 is moved into the rotor shaft 4. The inflowing cooling oil is partially allowed to flow into the case 20. Thereby, the pressure increase in the rotor shaft 4 accompanying the further increase in the rotation speed can be suppressed.

Further, the amount of the cooling oil stored in the case 20 is increased by the increase in the number of rotations of the rotor 3, and the liquid level of the cooling oil stored in the case 20 is lowered (FIG. 2 height L1 → L2). However, in the present embodiment, the cooling oil flows into the case 20 from the rotor shaft 4 through the second valve 34, so that the liquid level of the cooling oil stored in the case 20 is increased. Can be raised (L2 → L3 in FIG. 2), and the liquid surface height can be kept above a certain level (in this case, L2 or more). Therefore, even if the rotational speed of the rotor 3 fluctuates, an increase in friction can be suppressed while maintaining the cooling function by the cooling oil.
Here, the line A in FIG. 2 will be described. The line A is a reference line for making the oil surface that can cool the stator 11 without causing the rotor 3 to be immersed in oil (not causing friction). The height of the line A shown in FIG. 2 is an example, and is adjusted as appropriate according to the characteristics of the motor 1 and the control content.

  Further, by using the second valve 34 that is changed from the closed state to the open state by the pressure in the rotor 3, even when the rotational speed of the rotor 3 fluctuates, the rotor 3 is maintained while maintaining the pressure in the rotor 3 properly. 3 can be driven.

  Here, the first valve 33 is provided on the radially outer side of the rotor 3 than the second valve 34. When the first valve 33 is in an open state, the cooling oil in the rotor shaft 4 is discharged. Since it opens in the said case 20 from the radial direction outer side of the said rotor 3, the liquid level height of the cooling oil stored in the said case 20 can be made higher.

Further, since the second valve 34 is provided radially inward of the rotor 3 relative to the first valve 33, the second valve 34 is opened until the rotor 3 reaches the second rotational speed N2. Even when the state is reached, a part of the cooling oil in the rotor shaft 4 is stored in a portion on the outer peripheral side of the second valve 34.
Accordingly, the liquid level height of the cooling oil stored in the case 20 can be kept at a certain level or more, and the liquid level height can be kept lower than when the first valve 33 is in an open state. The effect of ensuring the cooling effect can be enhanced while suppressing the friction caused by the coolant.

  Further, when the temperature of the cooling oil in the rotor shaft 4 becomes equal to or higher than a predetermined temperature, the cooling oil in the rotor shaft 4 is opened into the case 20 by the third valve 35, whereby the case 20 Since the liquid level height of the cooling oil stored in the rotor can be maintained above a certain level, the cooling effect of the rotor 3 can be enhanced and the magnetic force of the magnet 6 provided on the rotor 3 can be maintained above a certain level. The magnet 6 can be protected from high heat. Here, it is preferable that the third valve 35 is provided so as to be positioned on the outer peripheral side of the rotor shaft 4 in that the magnet 6 can be effectively cooled by the cooling oil flowing out from the third valve 35.

Of course, the contents of the present invention are not limited to the above-described embodiments. For example, the vehicle may be a hybrid vehicle including an engine and a motor as drive sources, or may be a vehicle including only a motor.
The arrangement positions of the valves 33 to 35 are not limited to those in the above-described embodiment, and the end surfaces on which the respective valves 33 to 35 are provided may be replaced, or may be provided on only one of the end surfaces. .
Further, an engine and a transmission may be arranged on both sides of the motor 1 and the drive shaft 2 of the motor 1 may be connected to them. In a four-wheel drive hybrid vehicle, a drive source may be provided on the rear side. You may comprise so that the motor 1 may be provided.
Moreover, although embodiment demonstrated the case where the mechanical oil pump 27 was used, you may use not only this but an electric oil pump.

It is principal part sectional drawing of the motor for electric vehicles in embodiment of this invention. It is a graph which shows the relationship between rotor rotation speed and the height of the oil level in a case.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Motor 2 ... Drive shaft 3 ... Rotor 4 ... Rotor shaft 20 ... Case 33 ... 1st valve (1st opening-closing member)
34. Second valve (second opening / closing member)
35 ... Third valve (third opening / closing member)

Claims (5)

It is provided with a motor as a vehicle drive source, and is applied to a liquid-cooled electric vehicle motor that circulates a coolant in a case that houses the motor.
A coolant is passed through the rotor shaft coupled to the drive shaft of the motor;
The rotor of the motor is provided with a first opening / closing member and a second opening / closing member,
The first opening / closing member is in an open state when the rotor is in a stopped state, and is moved from the open state to the closed state until the rotor rotates from the stopped state to a predetermined first rotational speed. Hold the coolant in the shaft,
The second opening / closing member changes from a closed state to an open state until the rotor reaches a predetermined second rotational speed greater than the first rotational speed, and opens the coolant in the rotor shaft into the case. A rotor cooling device for an electric vehicle motor.   The rotor cooling device for an electric vehicle motor according to claim 1, wherein the first opening / closing member is changed from an open state to a closed state by a centrifugal force generated by rotation of the rotor.   The rotor cooling device for an electric vehicle motor according to claim 1, wherein the second opening / closing member is changed from a closed state to an open state by pressure in the rotor. The rotor is provided with a third opening / closing member that changes its shape depending on temperature,
2. The electric motor according to claim 1, wherein the third opening member opens the coolant in the rotor shaft into the case when the temperature of the coolant in the rotor shaft becomes equal to or higher than a predetermined value. A rotor cooling device for a vehicle motor. The rotor cooling device for an electric vehicle motor according to claim 1, wherein the first opening / closing member is provided on a radially outer side of the rotor than the second opening / closing member.

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