CN113783360B - Cooling system for electric drive system - Google Patents

Abstract

The invention provides a cooling system for an electric drive system, which includes a reducer oil circuit for lubricating the reducer and a motor oil circuit for cooling the motor. The cooling system also includes: a first flow regulating valve, located at the Between the oil circuit of the device and the oil circuit of the motor; the second flow regulating valve is connected with the oil circuit of the motor; the oil pump is connected with the first flow regulating valve and connected with the oil circuit flowing out of the second flow regulating valve; the first flow regulating valve Control the flow distribution to the reducer oil circuit and the motor oil circuit, the second flow regulating valve controls the oil flow flowing to the motor stator and motor rotor; the oil pump controls the oil flow flowing to the first flow regulating valve. After adopting the above technical solution, the flow adjustment of the oil flowing into the motor/reducer and the motor stator/rotor can be realized.

Description

A cooling system for an electric drive system

technical field

The invention relates to the field of electric drive system control, in particular to a cooling system for the electric drive system.

Background technique

With the rapid development of new energy vehicles and strong support from the industry, the motor in new energy vehicles, as the most critical component, has developed rapidly in recent years. According to the various needs of the user end, the motor control strategy and cooling strategy are gradually refined and optimized.

When the electric drive system is working, each subsystem needs to be lubricated and cooled by oil cooling. However, in the prior art, the oil cooling method is relatively simple, which cannot satisfy the problem that the demand for lubricating/cooling oil is different under different working conditions, or the flow distribution ratio of cooling oil cannot be adjusted.

Therefore, a new type of cooling system is needed, through the optimal allocation of oil volume, the waste of cooling oil flow can be avoided, thereby reducing the load of the oil pump and the system, reducing loss and reducing volume.

Contents of the invention

In order to overcome the above-mentioned technical defects, the object of the present invention is to provide a cooling system for an electric drive system, which can regulate the flow of oil flowing into the motor/reducer and motor stator/rotor.

The invention discloses a cooling system for an electric drive system, which includes a reducer oil circuit for lubricating the reducer and a motor oil circuit for cooling the motor. The cooling system also includes:

The first flow regulating valve is located between the reducer oil circuit and the motor oil circuit;

The second flow regulating valve is connected with the motor oil circuit;

The oil pump is connected with the first flow regulating valve, and connected with the oil circuit flowing out through the second flow regulating valve;

The first flow regulating valve controls the flow distribution to the reducer oil circuit and the motor oil circuit, and the second flow regulating valve controls the oil flow flowing to the motor stator and motor rotor;

The oil pump controls oil flow to the first flow regulating valve.

Preferably, the cooling system also includes:

The reducer cavity and the reducer transmission module located in the reducer cavity are connected with the reducer oil circuit, and the reducer transmission module includes:

The meshing tooth surface, the first bearing of the input shaft, the second bearing of the input shaft, the first bearing of the intermediate shaft, and the second bearing of the intermediate shaft are respectively connected with the oil circuit of the reducer to receive the cooling oil in the oil circuit of the reducer;

The filter is respectively connected with the cavity of the reducer and the oil pump;

The oil-water heat exchanger is respectively connected with the oil pump and the first flow regulating valve, and transmits the cooling oil that has cooled the inside of the cavity of the reducer to the first flow regulating valve.

Preferably, the cooling system also includes:

The motor cavity communicates with the reducer cavity;

The motor is arranged in the motor cavity, wherein the motor includes:

The motor bearing, the rotor shaft, and the stator core are respectively communicated with the second flow regulating valve to receive the cooling oil distributed by the second flow regulating valve;

The stator windings are respectively connected to the stator core and the rotor shaft to receive cooling oil flowing from the stator core and the rotor shaft;

The stator winding is arranged in the motor cavity, and the cooling oil flows back to the motor cavity after flowing through the stator winding, and then flows to the reducer cavity.

Preferably, the cooling system further includes a control module, which is electrically connected to the reducer, the motor, the oil pump, the first flow regulating valve, and the second flow regulating valve, and receives status information of the reducer, the motor, and the oil pump;

The control module is configured with a first control strategy for the first flow regulating valve, a second control strategy for the second flow regulating valve, a motor speed threshold, and an electric drive system load threshold;

The first control strategy and the second flow regulating valve control the opening of the first flow regulating valve and the second flow regulating valve based on the comparison results of the speed reducer and the state of the motor with the motor speed threshold and the load threshold of the electric drive system.

Preferably, the control module compares the current speed of the motor with the motor speed threshold;

The first control strategy includes:

When the current speed is lower than the motor speed threshold, the control oil pump applies cooling oil to the first flow regulating valve based on the first flow rate, and the first flow regulating valve is controlled by the control module to distribute the first branch flow to the reducer oil circuit and the motor oil The traffic of the second branch of the road, the traffic of the first branch is less than or equal to the traffic of the second branch;

When the current speed is greater than or equal to the motor speed threshold, the control oil pump applies cooling oil to the first flow regulating valve based on the second flow rate, and the first flow regulating valve is controlled by the control module to distribute the third branch flow to the oil circuit of the reducer and The flow rate of the fourth branch of the motor oil circuit, the flow rate of the third branch is less than or equal to the flow rate of the fourth branch;

The second control strategy includes:

When the current speed is less than the motor speed threshold, the second flow regulating valve is controlled by the control module to distribute the first rotor flow flowing to the motor rotor and the first stator flow flowing to the motor stator, and the first rotor flow is greater than or equal to the first Stator flow;

When the current speed is greater than or equal to the motor speed threshold, the second flow regulating valve is controlled by the control module to distribute the second rotor flow flowing to the motor rotor and the second stator flow flowing to the motor stator, and the second rotor flow is smaller than the second stator flow flow.

Preferably, the control module compares the current load of the electric drive system with a load threshold of the electric drive system;

The first control strategy includes:

When the current speed is less than the motor speed threshold and the current load of the electric drive system is less than the load threshold of the electric drive system, reduce the first flow rate;

When the current speed is less than the motor speed threshold and the current load of the electric drive system is greater than or equal to the load threshold of the electric drive system, increase the flow rate of the first branch;

The second control strategy includes:

When the current speed is greater than or equal to the motor speed threshold, and the current load of the electric drive system is less than the load threshold of the electric drive system, increase the second stator flow;

When the current speed is greater than or equal to the motor speed threshold and the current load of the electric drive system is greater than or equal to the load threshold of the electric drive system, increase the second rotor flow and the second stator flow, and control the second rotor flow to be greater than the second stator flow.

Preferably, the control module collects any one or more items of electrical frequency, current, motor efficiency, motor loss, stator temperature, rotor temperature, and oil temperature of the motor to form state information of the reducer, motor, and oil pump.

After adopting the above technical solution, compared with the prior art, it has the following beneficial effects:

1. Adjust the distribution of cooling oil under comprehensive consideration of motor speed and output torque, so as to ensure good lubrication of parts and cooling performance under high load

2. Through the reasonable distribution of the flow rate, the power demand for the oil pump is reduced, so as to reduce the load generated by the work of the oil pump;

3. Due to the function of flow distribution, the electronic pump can also be replaced by a mechanical pump, and the flow adjustment can be realized based on the mechanical pump, which further reduces the cost.

Description of drawings

Fig. 1 is a schematic structural diagram of a cooling system in accordance with a preferred embodiment of the present invention.

Detailed ways

The advantages of the present invention will be further elaborated below in conjunction with the accompanying drawings and specific embodiments.

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numerals in different drawings refer to the same or similar elements unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatuses and methods consistent with aspects of the present disclosure as recited in the appended claims.

The terminology used in the present disclosure is for the purpose of describing particular embodiments only, and is not intended to limit the present disclosure. As used in this disclosure and the appended claims, the singular forms "a", "the", and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It should also be understood that the term "and/or" as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

It should be understood that although the terms first, second, third, etc. may be used in the present disclosure to describe various information, the information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of the present disclosure, first information may also be called second information, and similarly, second information may also be called first information. Depending on the context, the word "if" as used herein may be interpreted as "at" or "when" or "in response to a determination."

In describing the present invention, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientations or positional relationships indicated by "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than Nothing indicating or implying that a referenced device or element must have a particular orientation, be constructed, and operate in a particular orientation should therefore not be construed as limiting the invention.

In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be mechanical connection or electrical connection, or two The internal communication of each element may be directly connected or indirectly connected through an intermediary. Those skilled in the art can understand the specific meanings of the above terms according to specific situations.

In the following description, use of suffixes such as 'module', 'part' or 'unit' for denoting elements is only for facilitating description of the present invention and has no specific meaning by itself. Therefore, "module" and "component" may be mixedly used.

Referring to FIG. 1 , it is a schematic structural diagram of a cooling system in accordance with a preferred embodiment of the present invention. In this embodiment, the cooling system includes a speed reducer and a motor, and the cooling objects of the cooling system are the speed reducer and the motor. Therefore, a reducer oil circuit for lubricating the reducer and a motor oil circuit for cooling the motor are provided. In order to control the oil supply mode of the reducer oil circuit and the motor oil circuit under different working conditions, the cooling system also includes a first A flow regulating valve, a second flow regulating valve and an oil pump, wherein the first flow regulating valve is set between the oil circuit of the reducer and the oil circuit of the motor, and the first flow regulating valve is adjusted according to its own opening to allocate the flow to the oil circuit of the reducer The ratio configuration of the cooling oil and the motor oil circuit, the second flow regulating valve is set on the motor oil circuit, and then connected with the motor stator and the motor rotor, and the ratio configuration of the cooling oil flowing to the motor stator and motor rotor is adjusted. And the oil pump is connected with the first flow regulating valve, and is connected with the oil circuit flowing out through the second flow regulating valve. On the one hand, it closes the entire oil circuit to form a circulating oil circuit; on the other hand, as a global control of the entire oil circuit, it controls the flow of the entire oil circuit.

With the above configuration, the working efficiency of the oil pump can be controlled first, the cooling efficiency of the reducer oil circuit and the motor oil circuit can be directly controlled, and then the separation flow rate when the cooling oil is separated for the first time can be controlled through the control of the first flow regulating valve, and again Through the control of the second flow regulating valve, the separation flow rate of the cooling oil during the secondary separation is controlled, so that the reducer, motor stator, and motor rotor receive the appropriate cooling oil for cooling under different working conditions and at different temperatures. There will be no excessive temperature rise due to too little cooling oil, and no waste of power consumption due to too much cooling oil.

In a preferred embodiment, the cooling system further includes: a reducer cavity and a reducer transmission module located in the reducer cavity, which communicates with the reducer oil circuit, wherein the reducer transmission module includes: meshing tooth surfaces, an input shaft The first bearing, the second bearing of the input shaft, the first bearing of the intermediate shaft, and the second bearing of the intermediate shaft are respectively connected to the reducer oil passage to receive the cooling oil in the reducer oil passage; the filter is respectively connected to the reducer chamber The body and the oil pump are connected; the oil-water heat exchanger is connected with the oil pump and the first flow regulating valve respectively, and transmits the cooling oil that has cooled the inside of the reducer cavity to the first flow regulating valve. Through the configuration of the reducer cavity and its interior, part of the cooling oil distributed by the first flow regulating valve to the reducer oil circuit will completely cool the reducer inside.

Furthermore, on the motor side, the cooling system includes: a motor cavity communicating with the reducer cavity; a motor disposed in the motor cavity, wherein the motor includes: a motor bearing, a rotor shaft, and a stator core, respectively connected to the second The flow regulating valve is connected to receive the cooling oil distributed by the second flow regulating valve; the stator winding is respectively connected with the stator core and the rotor shaft to receive the cooling oil flowing out from the stator core and the rotor shaft; the stator winding is set In the motor cavity, the cooling oil flows through the stator winding and then returns to the motor cavity, and then flows to the reducer cavity. Through the configuration of the motor cavity and the inside, part of the cooling oil distributed to the motor stator and the motor rotor through the second flow regulating valve will completely cool the inside of the motor.

In the above embodiment, the first flow regulating valve and the second flow regulating valve can properly distribute the flow of the gear shaft according to the oil churning of the reducer, and at the same time, properly distribute the flow of the motor according to the heat generation of the motor in each working condition. Speed and tail bearing lubrication, properly distribute stator and rotor flow.

In order to further control the oil pump, the first flow regulating valve, and the second flow regulating valve, the cooling system also includes a control module, which is electrically connected with the reducer, the motor, the oil pump, the first flow regulating valve, and the second flow regulating valve, and receives the reducer , motor, and oil pump status information, so that control instructions can be formed based on the above status information. Further, the control module is configured with a first control strategy for the first flow regulating valve, a second control strategy for the second flow regulating valve, a motor speed threshold, and an electric drive system load threshold; under different strategy logics, the second The first control strategy and the second flow adjustment valve control the opening of the first flow adjustment valve and the second flow adjustment based on the comparison results of the speed reducer and the motor state with the motor speed threshold and the load threshold of the electric drive system, so as to make flow adjustment.

The control module divides the motor speed into a low-speed state and a high-speed state according to comparing the current speed of the motor with the motor speed threshold. In different embodiments, in the low-speed state and the high-speed state, the first control strategy and the second control strategy include respectively :

first control strategy

When the current speed is less than the motor speed threshold (low speed), the control oil pump applies cooling oil to the first flow regulating valve based on the first flow rate, and the first flow regulating valve is controlled by the control module to distribute the flow to the first branch of the reducer oil circuit The flow rate of the second branch of the motor oil circuit, and the flow rate of the first branch is less than or equal to the flow rate of the second branch, that is, at low speed, the reducer consumes less power and generates less heat, and the main cooling oil will be distributed to the motor oil side;

When the current speed is greater than or equal to the motor speed threshold (high speed), the control oil pump applies cooling oil to the first flow regulating valve based on the second flow rate, and the first flow regulating valve is controlled by the control module to distribute the flow to the third oil circuit of the reducer. The branch flow and the fourth branch flow of the motor oil circuit, the third branch flow is less than or equal to the fourth branch flow, that is, at high speed, although the power consumption of the reducer is high, it will generate a lot of heat, but relatively, With more heat on the motor side, more cooling oil still needs to be distributed to the motor oil side.

Second control strategy

When the current speed is less than the motor speed threshold (low speed), the second flow regulating valve is controlled by the control module to distribute the first rotor flow to the motor rotor and the first stator flow to the motor stator, and the first rotor flow is greater than or equal to the first stator flow;

When the current speed is greater than or equal to the motor speed threshold (high speed), the second flow regulating valve is controlled by the control module to distribute the second rotor flow to the motor rotor and the second stator flow to the motor stator. The second rotor flow is less than Second stator flow.

In addition to the rotational speed, the control module will also consider the load condition of the electric drive system, which compares the current load of the electric drive system with the load threshold of the electric drive system, and divides the load into a low load state and a high load state. In different embodiments, the low Load state and high load state, the first control strategy and the second control strategy respectively include:

first control strategy

When the current speed is less than the motor speed threshold and the current load of the electric drive system is less than the load threshold of the electric drive system, reduce the first flow rate;

When the current rotation speed is less than the motor rotation speed threshold and the current load of the electric drive system is greater than or equal to the load threshold of the electric drive system, the flow rate of the first branch is increased.

Second control strategy

When the current speed is greater than or equal to the motor speed threshold, and the current load of the electric drive system is less than the load threshold of the electric drive system, increase the second stator flow;

When the current speed is greater than or equal to the motor speed threshold and the current load of the electric drive system is greater than or equal to the load threshold of the electric drive system, increase the second rotor flow and the second stator flow, and control the second rotor flow to be greater than the second stator flow.

In other words, when the speed is high and the load is high, the flow rate of the reducer can be appropriately increased to protect the tooth surface and the bearing, and the flow rate of the rotor can be appropriately reduced under the condition of high speed and low load to improve the dynamic balance performance of the rotor. On the contrary, the flow rate of the motor can be increased under the condition of high load. It is convenient for the heat dissipation of the motor. Or, under high-speed working conditions, the reducer can form good lubrication by stirring oil, and the oil exists in the form of mist inside the reducer, so the amount of oil in the reducer oil circuit can be reduced, and under high-speed and low-load conditions, The flow of cooling oil is mainly concentrated in the stator of the motor. At this time, due to the consideration of dynamic balance, the flow of the rotor is relatively small; under the condition of high speed and high load, on the basis of the above, the flow of the stator and rotor should be increased at the same time, and the flow ratio of the rotor should be increased. . On the other hand, under low-speed conditions and further low-load conditions, the reducer and motor have no obvious lubrication and heat generation, so the power consumption of the vehicle can be reduced by reducing the oil supply; and under high-load conditions , The reducer is low-speed and heavy-loaded, so a certain amount of cooling oil is needed to lubricate the tooth surface. At this time, the flow rate of the reducer should be increased appropriately; for the motor, the heat at this time is mainly concentrated in the stator, so the flow rate of the stator should be increased.

It can be understood that, in addition to the above-mentioned first control strategy and second control strategy, targeted control strategies can be configured according to different working conditions, or when the overall flow rate is constant and the opening of each flow control valve is constant Under the condition that increasing the opening of a certain flow control valve will increase the flow of the oil circuit corresponding to the valve; while increasing the speed of the oil pump will increase the flow of all oil circuits when the opening of all valves remains the same.

In any of the above embodiments, the control module collects any one or more of the electric frequency, current, motor efficiency, motor loss, stator temperature, rotor temperature, and oil temperature of the motor to form the speed reducer, motor, and oil pump. status information.

It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any form. Any person skilled in the art may use the technical content disclosed above to change or modify equivalent effective embodiments However, any modifications or equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belong to the scope of the technical solution of the present invention.

Claims (4)

1. A cooling system for an electric drive system, comprising a reducer oil circuit for lubricating the reducer and a motor oil circuit for cooling the motor, characterized in that the cooling system also includes: The first flow regulating valve is arranged between the oil circuit of the reducer and the oil circuit of the motor; The second flow regulating valve is connected with the motor oil circuit; An oil pump, connected to the first flow regulating valve, and connected to the oil passage flowing out through the second flow regulating valve; The first flow regulating valve controls the flow distribution to the reducer oil circuit and the motor oil circuit, and the second flow regulating valve controls the oil flow flowing to the motor stator and motor rotor; The oil pump controls the oil flow flowing to the first flow regulating valve, and increases the speed of the oil pump to increase the flow of all oil circuits; The cooling system also includes a control module, which is electrically connected to the reducer, motor, oil pump, first flow regulating valve, and second flow regulating valve, and receives status information of the reducer, motor, and oil pump; The control module is configured with a first control strategy for the first flow regulating valve, a second control strategy for the second flow regulating valve, a motor speed threshold, and an electric drive system load threshold; The first control strategy and the second flow regulating valve control the opening of the first flow regulating valve and the second flow regulating valve based on the comparison results of the speed reducer and the state of the motor with the motor speed threshold and the load threshold of the electric drive system; The control module compares the current speed of the motor with the motor speed threshold; The first control strategy includes: When the current speed is less than the motor speed threshold, control the oil pump to apply cooling oil to the first flow regulating valve based on the first flow rate, and the first flow regulating valve is controlled by the control module to distribute the flow to the reducer oil circuit The first branch flow of the motor oil circuit and the second branch flow of the motor oil circuit, the first branch flow is less than or equal to the second branch flow; When the current speed is greater than or equal to the motor speed threshold, the oil pump is controlled to apply cooling oil to the first flow regulating valve based on the second flow rate, and the first flow regulating valve is controlled by the control module to distribute the flow to the speed reducer The third branch flow of the oil circuit and the fourth branch flow of the motor oil circuit, the third branch flow is less than or equal to the fourth branch flow; The second control strategy includes: When the current speed is less than the motor speed threshold, the second flow regulating valve is controlled by the control module to distribute the first rotor flow flowing to the motor rotor and the first stator flow flowing to the motor stator, the first rotor The flow rate is greater than or equal to the first stator flow rate; When the current speed is greater than or equal to the motor speed threshold, the second flow regulating valve is controlled by the control module to distribute the second rotor flow flowing to the motor rotor and the second stator flow flowing to the motor stator, the second The rotor flow rate is less than the second stator flow rate; The control module also compares the current load of the electric drive system to a load threshold of the electric drive system; The first control strategy includes: When the current speed is less than the motor speed threshold and the current load of the electric drive system is less than the load threshold of the electric drive system, reduce the first flow rate; When the current speed is less than the motor speed threshold and the current load of the electric drive system is greater than or equal to the load threshold of the electric drive system, increase the flow rate of the first branch; The second control strategy includes: When the current speed is greater than or equal to the motor speed threshold, and the current load of the electric drive system is less than the load threshold of the electric drive system, increase the second stator flow; When the current speed is greater than or equal to the motor speed threshold and the current load of the electric drive system is greater than or equal to the load threshold of the electric drive system, increase the second rotor flow and the second stator flow, and control the second rotor flow to be greater than the second stator flow. 2. The cooling system according to claim 1, further comprising: The reducer cavity and the reducer transmission module located in the reducer cavity communicate with the reducer oil passage, wherein the reducer transmission module includes: The meshing tooth surfaces, the first bearing of the input shaft, the second bearing of the input shaft, the first bearing of the intermediate shaft, and the second bearing of the intermediate shaft are respectively connected to the oil circuit of the reducer to receive cooling oil in the oil circuit of the reducer; A filter is connected to the cavity of the reducer and the oil pump respectively; The oil-water heat exchanger is respectively connected with the oil pump and the first flow regulating valve, and transmits the cooling oil that has cooled the inside of the reducer cavity to the first flow regulating valve. 3. The cooling system according to claim 2, further comprising: The motor cavity communicates with the reducer cavity; The motor is arranged in the motor cavity, wherein the motor includes: The motor bearing, the rotor shaft, and the stator core are respectively communicated with the second flow regulating valve to receive the cooling oil distributed by the second flow regulating valve; Stator windings connected to the stator core and the rotor shaft, respectively, to receive cooling oil flowing from the stator core and the rotor shaft; The stator winding is arranged in the motor cavity, and the cooling oil flows back to the motor cavity after flowing through the stator winding, and then flows to the reducer cavity. 4. The cooling system according to claim 1, wherein the control module collects any one of electrical frequency, current, motor efficiency, motor loss, stator temperature, rotor temperature, and oil temperature of the motor or Multiple items to form the status information of the reducer, motor, and oil pump.

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