Torque Distribution Method for Hybrid Electric Vehicles

Abstract

The present invention discloses a torque distribution method for a hybrid vehicle, comprising: S1: obtaining current driving condition parameters, and determining a current vehicle demand torque including a target engine torque and a target motor torque according to the current driving condition parameters and a torque characteristic map; S2: obtaining the current coolant temperature, and determining an execution torque of the motor and an execution torque of the engine; if the current coolant temperature is less than or equal to a first temperature threshold or greater than or equal to a second temperature threshold, the execution torque of the motor and the execution torque of the engine are respectively the target motor torque and the target engine torque; if the current coolant temperature is greater than the first temperature threshold and less than the second temperature threshold, determining a torque correction coefficient according to the current coolant temperature and a preset torque correction map, correcting the target motor torque and the target engine torque according to the torque correction coefficient, the execution torque of the motor being the corrected motor torque, and the execution torque of the engine being the corrected engine torque, which can reduce the vehicle energy consumption.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicles, and particularly relates to a torque distribution method for a hybrid vehicle. Background Art

[0002] The current hybrid power solutions for passenger cars can effectively reduce the CO2 tailpipe emissions of vehicles. Since there are two power sources, namely an engine and a drive motor / power battery, the torque / power distribution of the engine and the drive motor can be dynamically and flexibly adjusted under different vehicle speeds and different acceleration conditions. The general principle is that in the inefficient region of the engine, the vehicle is driven by the drive motor, and when the engine is in the efficient region, the engine intervenes to work, charging the power battery or driving the wheels simultaneously. At the same time, when the engine intervenes to work, the working load of the engine is generally optimized by a dynamic programming algorithm, so that the overall vehicle energy consumption is the lowest when the state of charge (SOC) of the battery meets the requirements. The current torque / power distribution strategy of the engine and the drive motor of hybrid vehicles is based on the efficiency of the engine, the drive motor, the transmission, the conversion of the voltage of the DC power supply (DC / DC), and the battery charging / discharging efficiency, and uses a dynamic programming algorithm to formulate the strategy, as Figure 1 shown.

[0003] However, the working process of a general mainstream gasoline engine is as follows: gasoline and air are fully mixed in the combustion chamber and ignited. This causes a high-temperature and high-pressure mixture to be generated in the combustion chamber. While the high-temperature and high-pressure mixture pushes the piston to do external work, it will continuously dissipate heat to the cylinder wall and overcome the friction work of components such as the piston. Finally, the remaining work will be transmitted to the transmission end through the crankshaft. Therefore, from the above theory, it can be seen that the amount of heat dissipated externally and the amount of friction work during the work process of the gasoline engine will affect the effective work output of the engine, thereby affecting the fuel consumption of the engine. That is, when the coolant temperature is low, more heat is dissipated from the combustion chamber, and the oil temperature is also low, so the friction work will increase. Then, under the condition of the same effective work output, the fuel consumption is high. On the contrary, the fuel consumption is low. Figure 2 is the fuel consumption change of an engine at different coolant temperatures. As Figure 2 shown, under the same engine torque and motor torque distribution, the lower the coolant temperature, the higher the fuel consumption. For example, when the coolant temperature is 30°C, its fuel consumption will be 10% higher than that at the normal temperature (90°C). When the coolant temperature is above 80°C, its fuel consumption is the same as that at the normal temperature (90°C). Therefore, the torque / power distribution strategy of the engine and the drive motor of hybrid vehicles has not considered the factor of coolant temperature, which will affect the determination of lower overall vehicle energy consumption. Summary of the Invention

[0004] The object of the present invention is to solve the problem in the prior art that the factor of coolant temperature is not considered, which will affect the determination of lower vehicle energy consumption. The present invention provides a torque distribution method for a hybrid vehicle, which can further reduce the vehicle energy consumption.

[0005] An embodiment of the present invention discloses a torque distribution method for a hybrid vehicle, including the following steps:

[0006] S1: Obtain the current driving condition parameters of the vehicle, and determine the current vehicle demand torque according to the current driving condition parameters and the torque characteristic diagram; wherein, the current driving condition parameters include the current throttle opening and the current vehicle speed, and the current vehicle demand torque includes the target engine torque and the target motor torque.

[0007] S2: Obtain the current coolant temperature of the engine, and determine the execution torque of the motor and the execution torque of the engine according to the current coolant temperature, the target engine torque, and the target motor torque; wherein,

[0008] if the current coolant temperature is less than or equal to the first temperature threshold, the engine is in a cold state; if the current coolant temperature is greater than or equal to the second temperature threshold, the engine is in a hot state, wherein the second temperature threshold is greater than the first temperature threshold; when the engine is in a cold state or a hot state, the execution torque of the motor is the target motor torque, and the execution torque of the engine is the target engine torque;

[0009] if the current coolant temperature is greater than the first temperature threshold and less than the second temperature threshold, the engine is in a warm-up stage, determine the torque correction coefficient according to the current coolant temperature and the preset torque correction diagram, and correct the target motor torque and the target engine torque according to the torque correction coefficient to obtain the corrected engine torque and the corrected motor torque; the execution torque of the motor is the corrected motor torque, and the execution torque of the engine is the corrected engine torque.

[0010] By adopting the above technical solution, when formulating the torque distribution strategy of the engine and the motor, on the basis of the target engine torque and the target motor torque obtained according to the current driving condition parameters and the torque characteristic diagram, the influence factor of the coolant temperature of the engine on fuel consumption is added, that is, obtain the current coolant temperature of the engine, determine whether the engine is in a cold stage, a warm-up stage or a hot stage according to the current coolant temperature, if the engine is in a warm-up stage, determine the torque correction coefficient according to the current coolant temperature, and correct the target engine torque and the target motor torque through the torque correction coefficient to obtain the corrected engine torque and the corrected motor torque; use the corrected motor torque as the execution torque of the motor, and use the corrected engine torque as the execution torque of the engine, which can further reduce the vehicle energy consumption.

[0011] According to another specific embodiment of the present invention, for the torque distribution method of a hybrid vehicle disclosed in the embodiment of the present invention, if the engine is in the warm-up stage, the following steps are executed:

[0012] Determine the torque correction coefficient; wherein, when the target motor torque is a negative torque, the torque correction coefficient is determined according to the current coolant temperature and a preset torque correction map; wherein, the torque correction coefficient is greater than or equal to 1; when the target motor torque is a positive torque or 0, the torque correction coefficient is 1;

[0013] Correct the target motor torque according to the torque correction coefficient to obtain the corrected motor torque;

[0014] Determine the corrected engine torque according to the current vehicle demand torque and the corrected motor torque.

[0015] Adopting the above technical solution, when the target motor torque is a negative torque, the target motor torque is used as the power generation torque, and it is necessary to correct the power generation torque of the motor, that is, the power generation torque of the motor should be appropriately enlarged to additionally increase the engine load. The purpose is to quickly increase the coolant temperature. Since the higher the coolant temperature, the lower the fuel consumption rate of the engine, the fuel consumption of the engine can be further reduced.

[0016] According to another specific embodiment of the present invention, for the torque distribution method of a hybrid vehicle disclosed in the embodiment of the present invention, if the engine is in the warm-up stage, the range of the torque correction coefficient when the target motor torque is a negative torque is 1 to 1.5.

[0017] Adopting the above technical solution, the range of the torque correction coefficient is 1 to 1.5, which is equivalent to appropriately enlarging the torque when the target motor torque is a negative torque. If the engine is in the warm-up stage, the coolant temperature is relatively low and the fuel consumption rate is relatively high. It is necessary to appropriately enlarge the power generation torque of the motor to increase the engine load and quickly increase the coolant temperature, thereby further reducing the fuel consumption of the engine.

[0018] According to another specific embodiment of the present invention, for the torque distribution method of a hybrid vehicle disclosed in the embodiment of the present invention, if the engine is in the warm-up stage, the warm-up stage is divided into at least two sub-warm-up stages according to a preset coolant temperature threshold; wherein, the preset torque correction map includes at least two corresponding preset sub-torque correction maps, the preset coolant temperature threshold is greater than the first temperature threshold and less than the second temperature threshold; when the target motor torque is a negative torque, the torque correction coefficient is determined according to the current coolant temperature and the corresponding preset sub-torque correction map.

[0019] With the above technical solution, under the same motor and engine torque distribution, when the temperature of the coolant is different, the fuel consumption rate of the engine is different, that is, the fuel consumption rate of the engine is different. When the engine is in the warm-up stage and the target motor torque is negative torque, if the current coolant temperature is different, the corresponding correction factor should also be different. The warm-up stage is divided into at least two sub-warm-up stages according to the preset coolant temperature threshold, and the torque correction factor is determined according to the current coolant temperature and the corresponding preset sub-torque correction map to correct the generating torque of the motor. In this way, the generating torque of the motor is corrected by different torque correction factors corresponding to different sub-torque correction maps, which can further reduce the fuel consumption of the engine.

[0020] According to another specific embodiment of the present invention, in the torque distribution method of the hybrid vehicle disclosed in the embodiment of the present invention, the first temperature threshold is 35 °C and the second temperature threshold is 80 °C.

[0021] According to another specific embodiment of the present invention, in the torque distribution method of the hybrid vehicle disclosed in the embodiment of the present invention, the warm-up stage includes a first sub-warm-up stage and a second sub-warm-up stage; wherein, if the current coolant temperature is in the range of 35 °C to 50 °C, the engine is in the first sub-warm-up stage, and the range of the torque correction factor when the target motor torque is negative torque is 1.1 to 1.5; if the current coolant temperature is in the range of 50 °C to 80 °C, the engine is in the second sub-warm-up stage, and the range of the torque correction factor when the target motor torque is negative torque is 1 to 1.1.

[0022] With the above technical solution, the lower the coolant temperature, the higher the fuel consumption rate. Therefore, the fuel consumption rate of the engine with the coolant temperature in the range of 35 °C to 50 °C is higher than that of the engine with the coolant temperature in the range of 50 °C to 80 °C. Therefore, the torque correction factor when the target motor torque is negative torque when the engine is in the first sub-warm-up stage is set to be higher than the torque correction factor when the target motor torque is negative torque when the engine is in the second sub-warm-up stage. The magnification of the generating torque of the former motor is higher than that of the latter, which can increase the engine load as soon as possible, raise the coolant temperature as soon as possible, and further reduce the fuel consumption of the engine.

[0023] According to another specific embodiment of the present invention, the torque distribution method of the hybrid vehicle disclosed in the embodiment of the present invention, the first sub-warm-up stage includes a first front sub-warm-up stage, a first middle sub-warm-up stage, and a first rear sub-warm-up stage; wherein, if the current coolant temperature is within the range of 35°C to 40°C, the engine is in the first front sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.2 to 1.5; if the current coolant temperature is within the range of 40°C to 42°C, the engine is in the first middle sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.15 to 1.2; if the current coolant temperature is within the range of 42°C to 50°C, the engine is in the first rear sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.1 to 1.15.

[0024] Adopting the above technical solution, when the target motor torque is negative torque, the torque correction coefficient when the engine is in the first front sub-warm-up stage is set higher than the torque correction coefficient when the engine is in the first middle sub-warm-up stage, and the torque correction coefficient when the engine is in the first middle sub-warm-up stage is set higher than the torque correction coefficient when the engine is in the first rear sub-warm-up stage, which can quickly increase the engine load, quickly increase the coolant temperature, and further reduce the fuel consumption of the engine.

[0025] According to another specific embodiment of the present invention, the torque distribution method of the hybrid vehicle disclosed in the embodiment of the present invention, the second sub-warm-up stage includes a second front sub-warm-up stage and a second rear sub-warm-up stage; wherein, if the current coolant temperature is within the range of 50°C to 60°C, the engine is in the second front sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.05 to 1.1; if the current coolant temperature is within the range of 60°C to 80°C, the engine is in the second rear sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1 to 1.05.

[0026] Adopting the above technical solution, when the engine is in the second sub-warm-up stage, the coolant temperature is already high enough, and the fuel consumption rate is already relatively low at this time, so the torque correction coefficient is small. The torque correction coefficient when the engine is in the second rear sub-warm-up stage is significantly lower than the torque correction coefficient when the engine is in the second front sub-warm-up stage. This is because after the engine load is quickly increased in the first sub-warm-up stage, the coolant temperature is already relatively high, and the fuel consumption rate is already relatively low at this time, so the torque correction coefficient can be appropriately reduced, which can reduce the fuel consumption of the engine.

[0027] The beneficial effects of the present invention are:

[0028] The present invention provides a torque distribution method for a hybrid vehicle. When formulating the torque distribution strategy for the engine and the motor, on the basis of the target engine torque and the target motor torque obtained according to the current driving condition parameters and the torque characteristic diagram, the influence factor of the coolant temperature of the engine on fuel consumption is added, that is, the current coolant temperature of the engine is obtained, the torque correction coefficient is determined according to the current coolant temperature, and the target engine torque and the target motor torque are corrected by the torque correction coefficient to obtain the corrected engine torque and the corrected motor torque; the corrected motor torque is used as the execution torque of the motor, and the corrected engine torque is used as the execution torque of the engine, which can further reduce the energy consumption of the whole vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of the principle of the torque distribution method for the current hybrid vehicle;

[0030] Figure 2 is a schematic diagram of the change in fuel consumption of a certain engine at different coolant temperatures;

[0031] Figure 3 is a schematic diagram of the principle of the torque distribution method for the hybrid vehicle of the present embodiment;

[0032] Figure 4 is a flowchart of the torque distribution method for the hybrid vehicle of the present embodiment;

[0033] Figure 5 is a schematic diagram of the change in the torque correction coefficient of the motor generating torque at different coolant temperatures when the engine is in the warm-up stage in the torque distribution method for the hybrid vehicle of the present embodiment;

[0034] Figure 6 is a schematic diagram of the changes in the vehicle speed, the engine coolant temperature (water temperature), the motor torque of the torque distribution method for the current hybrid vehicle, and the motor torque of the torque distribution method for the hybrid vehicle of the present embodiment under standard driving conditions. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention will be introduced in conjunction with preferred embodiments, this does not mean that the features of this invention are limited to this implementation manner. On the contrary, the purpose of introducing the invention in conjunction with the implementation manner is to cover other alternatives or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, many specific details will be included in the following description. The present invention can also be implemented without using these details. In addition, in order to avoid confusing or obscuring the key points of the present invention, some specific details will be omitted in the description. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0036] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0037] In the description of this embodiment, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0038] The terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0039] In the description of this embodiment, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "connected", "connected to" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this embodiment can be understood according to specific situations.

[0040] To make the purpose, technical solutions and advantages of the present invention clearer, the implementation manners of the present invention will be further described in detail below with reference to the drawings.

[0041] As Figure 2 shown, under the same motor and engine torque distribution, the lower the coolant temperature, the higher the fuel consumption rate, that is, the higher the fuel consumption.

[0042] To solve the problem in the prior art that the factor of coolant temperature is not considered, which will affect the determination of lower vehicle energy consumption. The present invention provides a torque distribution method for a hybrid vehicle, as Figure 3 shown, on the basis of the current hybrid torque formulation strategy, the correction of the engine coolant temperature is added to determine a new torque distribution scheme, thereby further reducing the vehicle energy consumption.

[0043] Please refer to Figure 4 , an embodiment of the present invention discloses a torque distribution method for a hybrid vehicle, including the following steps: S1: Obtain the current driving condition parameters of the vehicle, and determine the current vehicle demand torque according to the current driving condition parameters and the torque characteristic map; wherein, the current driving condition parameters include the current throttle opening and the current vehicle speed, and the current vehicle demand torque includes the target engine torque and the target motor torque.

[0044] It should be noted that the torque characteristic map in this embodiment is obtained by using the dynamic programming algorithm, as Figure 1 shown, to obtain the vehicle speed, throttle opening, gear position, etc., with the lowest vehicle fuel consumption as the goal, the torque distribution of the motor and the engine as variables, and at the same time adding the state of charge (SOC) of the battery as a constraint condition, that is, to avoid excessive battery discharge, and combining all factors on the energy flow path such as motor efficiency, transmission efficiency, AC / DC converter efficiency, battery charge / discharge efficiency, etc., to calculate the fuel consumption under different torque distributions in real time, and finally the torque distribution strategy with the lowest fuel consumption can be obtained, that is, the torque characteristic map. Among them, the constraint conditions include that the battery SOC is greater than the state of charge threshold, and the state of charge threshold can be 20% - 30%. The abscissa of the torque characteristic map is the engine speed and the motor speed, and the ordinate corresponds to the engine torque, the motor speed, and the battery SOC. The sum of the target engine torque and the target motor torque is equal to the current total torque of the vehicle.

[0045] S2: Obtain the current coolant temperature of the engine, and determine the execution torque of the motor and the execution torque of the engine according to the current coolant temperature, the target engine torque, and the target motor torque; wherein, if the current coolant temperature is less than or equal to the first temperature threshold, the engine is in a cold state; if the current coolant temperature is greater than or equal to the second temperature threshold, the engine is in a hot state, where the second temperature threshold is greater than the first temperature threshold; when the engine is in a cold state or a hot state, the execution torque of the motor is the target motor torque, and the execution torque of the engine is the target engine torque. If the current coolant temperature is greater than the first temperature threshold and less than the second temperature threshold, the engine is in the warm-up stage. Determine the torque correction coefficient according to the current coolant temperature and the preset torque correction map, and correct the target motor torque and the target engine torque with the torque correction coefficient to obtain the corrected engine torque and the corrected motor torque; the execution torque of the motor is the corrected motor torque, and the execution torque of the engine is the corrected engine torque.

[0046] Specifically, in this embodiment, the first temperature threshold can be set to a relatively low temperature, such as 30°C, 35°C, etc., and the second temperature threshold can be set to a relatively high temperature, such as 70°C, 80°C, etc. If the current coolant temperature is less than or equal to the first temperature threshold, although the coolant temperature of the engine is very low at this time, it is in the emission ignition stage. The main purpose of the current stage is to make the aftertreatment system reach the normal working temperature as soon as possible. Emission is the primary consideration factor in this stage, so the drive motor torque is not corrected in this area. If the current coolant temperature is greater than the first temperature threshold and less than the second temperature threshold, the emission ignition stage has passed, and the aftertreatment system has reached the normal working temperature. At this time, the torque of the motor needs to be corrected to reduce the fuel consumption. After correcting the torque of the motor, the total current torque of the vehicle remains unchanged, that is, the sum of the corrected motor torque and the corrected engine torque is still equal to the total current torque of the vehicle. Therefore, the corrected engine torque can be determined. If the current coolant temperature is greater than or equal to the second temperature threshold, the coolant temperature of the engine is relatively high at this time, and the engine is in the hot state with a low fuel consumption rate. When the target motor torque is a positive torque, the target motor torque is used as the driving torque, and the motor will output more torque to assist the engine in driving the vehicle. This is because the charging load of the engine increases during the warm-up stage. While increasing the coolant temperature of the engine, the battery also obtains more power. Thus, in the hot state, the driving torque of the motor can have more torque to assist in driving the vehicle, thereby reducing the torque of the engine and further reducing the fuel consumption.

[0047] In a specific embodiment, if the engine is in the warm-up stage, the following steps are executed:

[0048] Determine the torque correction coefficient; among them, when the target motor torque is negative torque, determine the torque correction coefficient according to the current coolant temperature and the preset torque correction map; among them, the torque correction coefficient is greater than or equal to 1; when the target motor torque is positive torque or 0, the torque correction coefficient is 1.

[0049] Correct the target motor torque according to the torque correction coefficient to obtain the corrected motor torque.

[0050] Determine the corrected engine torque according to the current vehicle demand torque and the corrected motor torque.

[0051] It should be noted that in this embodiment, when the target motor torque is negative torque, it means that the engine actively charges the battery, that is, the target motor torque is the generating torque; when the target motor torque is positive torque, it means that the motor assists the engine to drive the vehicle, that is, the target motor torque is the driving torque. Specifically, if the engine is in the warm-up stage, the engine coolant temperature needs to increase from a low temperature such as 30°C, 35°C, etc. to a high temperature such as 70°C, 80°C, etc. Since the lower the engine coolant temperature, the higher the fuel consumption of the engine, it is necessary to increase the engine coolant temperature as soon as possible, and it is necessary to appropriately increase the generating torque of the motor to increase the load of the engine.

[0052] It should be noted that in this embodiment, the lower the engine coolant temperature, the greater the expansion coefficient of the motor generating torque. Figure 5 This is a schematic diagram of the change of the torque correction coefficient of the motor generating torque at different coolant temperatures when the engine is in the warm-up stage in the torque distribution method of the hybrid vehicle in this embodiment. As Figure 5 shown, for example, when the engine coolant temperature is lower than 30°C, the torque correction coefficient of the motor generating torque can be 1.5, that is, the target motor torque can be expanded by 1.5 times; when the engine coolant temperature is 40°C, the torque correction coefficient of the motor generating torque can be 1.2, that is, the target motor torque can be expanded by 1.2 times; in the range of 30°C to 45°C, the torque correction coefficient of the motor generating torque gradually decreases with the increase of the coolant temperature, that is, the expansion multiple of the target motor torque gradually decreases with the increase of the coolant temperature.

[0053] In this embodiment, Figure 6 This is a schematic diagram of the vehicle speed, engine coolant temperature (water temperature) of the hybrid vehicle under the standard driving condition, the motor torque of the torque distribution method of the current hybrid vehicle, and the change of the motor torque of the torque distribution method of the hybrid vehicle in this embodiment. Currently, the NEDC (New Europe Drive Cycle) working condition road spectrum is adopted for the standard driving condition. As Figure 6As shown, when in the constant-speed working condition of 35 km / h, the original motor torque is negative, and the corrected motor torque is even lower, that is, the engine increases its on-road charging load, and more energy is used for battery charging. Moreover, the lower the coolant temperature, the greater the motor generating torque, that is, the smaller the negative value, and at the same time, the greater the increase in engine load. That is, in this embodiment, after adding the thermal management correction factor, the engine load will be additionally increased, aiming to quickly increase the coolant temperature to reduce the fuel consumption of the engine.

[0054] In a specific embodiment, when the engine is in the warm-up stage, the range of the torque correction coefficient when the target motor torque is negative torque is 1 to 1.5. It should be noted that when the engine is in the warm-up stage, the lower the coolant temperature, the greater the torque correction coefficient when the target motor torque is negative torque.

[0055] In a specific embodiment, when the engine is in the warm-up stage, the warm-up stage is divided into at least two sub-warm-up stages according to a preset coolant temperature threshold; wherein, the preset torque correction map includes at least two corresponding preset sub-torque correction maps, the preset coolant temperature threshold is greater than the first temperature threshold and less than the second temperature threshold; when the target motor torque is negative torque, the torque correction coefficient is determined according to the current coolant temperature and the corresponding preset sub-torque correction map.

[0056] In this embodiment, the number of preset coolant temperature thresholds is at least one. According to at least one preset coolant temperature threshold, the warm-up stage can be divided into two sub-warm-up stages, three sub-warm-up stages, four sub-warm-up stages, or even more sub-warm-up stages. For example, one preset coolant temperature threshold can divide two sub-warm-up stages, and two preset coolant temperature thresholds can divide three sub-warm-up stages. This embodiment does not make specific limitations on this. Each sub-warm-up stage corresponds to a sub-torque correction map. Those skilled in the art can determine the specific value of each preset coolant temperature threshold according to actual needs. For example, if it is divided into two sub-warm-up stages, one preset coolant temperature threshold needs to be set, and this preset coolant temperature threshold can be 40°C, 50°C, 60°C, etc., or other temperatures can also be set. Those skilled in the art can set it according to needs, and this embodiment does not make specific limitations on this.

[0057] With the above technical solution, when the engine is in the warm-up stage and the coolant temperature is between 35°C and 80°C, different coolant temperatures result in different fuel consumption rates of the engine. When the target motor torque is negative torque, the warm-up stage is divided into at least two sub-warm-up stages according to the coolant temperature, and the torque correction coefficient is determined based on the current coolant temperature and the corresponding preset sub-torque correction map to correct the generating torque of the motor. In this way, by using different torque correction coefficients corresponding to different sub-torque correction maps to correct the generating torque of the motor, the fuel consumption of the engine can be further reduced.

[0058] In a specific embodiment, the first temperature threshold is 35°C and the second temperature threshold is 80°C.

[0059] In a specific embodiment, the warm-up stage includes a first sub-warm-up stage and a second sub-warm-up stage; wherein, if the current coolant temperature is within the range of 35°C to 50°C, the engine is in the first sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.1 to 1.5; if the current coolant temperature is within the range of 50°C to 80°C, the engine is in the second sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1 to 1.1.

[0060] In this embodiment, as Figure 2 shown, the fuel consumption rate of the engine with the coolant temperature within the range of 35°C to 50°C is higher than that of the engine with the coolant temperature within the range of 50°C to 80°C. Therefore, the range of the torque correction coefficient when the target motor torque is negative torque when the engine is in the first sub-warm-up stage is higher than the range of the torque correction coefficient when the target motor torque is negative torque when the engine is in the second sub-warm-up stage. The magnification of the generating torque of the former motor is higher than that of the latter, which can quickly increase the engine load, quickly increase the coolant temperature, and further reduce the fuel consumption of the engine.

[0061] In a specific embodiment, the first sub-warm-up stage includes a first pre-sub-warm-up stage, a first mid-sub-warm-up stage, and a first post-sub-warm-up stage; wherein, if the current coolant temperature is within the range of 35°C to 40°C, the engine is in the first pre-sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.2 to 1.5; if the current coolant temperature is within the range of 40°C to 42°C, the engine is in the first mid-sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.15 to 1.2; if the current coolant temperature is within the range of 42°C to 50°C, the engine is in the first post-sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.1 to 1.15.

[0062] With the above technical solution, when the target motor torque is negative torque, the torque correction coefficient when the engine is in the first front sub-warm-up stage is set to be higher than the torque correction coefficient when the engine is in the first middle sub-warm-up stage, and the torque correction coefficient when the engine is in the first middle sub-warm-up stage is set to be higher than the torque correction coefficient when the engine is in the first rear sub-warm-up stage, which can increase the engine load as soon as possible, increase the coolant temperature as soon as possible, and further reduce the fuel consumption of the engine.

[0063] In a specific embodiment, the second sub-warm-up stage includes a second front sub-warm-up stage and a second rear sub-warm-up stage; wherein, if the current coolant temperature is in the range of 50°C to 60°C, the engine is in the second front sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.05 to 1.1; if the current coolant temperature is in the range of 60°C to 80°C, the engine is in the second rear sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1 to 1.05. Specifically, when the engine is in the second sub-warm-up stage, the coolant temperature is already high enough, and at this time the fuel consumption rate is already relatively low, so the torque correction coefficient is small. The torque correction coefficient when the engine is in the second rear sub-warm-up stage is significantly lower than the torque correction coefficient when the engine is in the second front sub-warm-up stage, because after the engine load is rapidly increased in the first sub-warm-up stage, the coolant temperature is already relatively high, and at this time the fuel consumption rate is already relatively low, and the torque correction coefficient can be appropriately reduced, which can reduce the fuel consumption of the engine.

[0064] It should be noted that in this embodiment, from the perspective of simulation, the influence of the current torque distribution method of the hybrid vehicle and the torque distribution method provided in this embodiment on the energy consumption of the engine is compared. The simulation results show that after adding the thermal management correction factor, in the stage where the engine coolant temperature is low, the engine will increase the load of driving for charging, so that the engine can increase the temperature rise as soon as possible, and at the same time the battery obtains more power. In the stage where the coolant temperature is high, the motor can have more torque to assist in driving the vehicle. Further simulation shows that the torque distribution method after thermal management correction can reduce the comprehensive energy consumption by 0.04 L / 100 km. At the same time, since theoretical simulation calculations show that the energy consumption benefit is 0.04 L / 100 km, which is about a 1% reduction, and the error of the chassis dynamometer test exceeds this percentage, the test cannot well reflect the effect of this strategy, and the actual energy consumption benefit should be higher.

[0065] The present invention provides a torque distribution method for a hybrid vehicle. When formulating the torque distribution strategy of the engine and the motor, on the basis of the target engine torque and the target motor torque obtained according to the current driving condition parameters and the torque characteristic map, the influence factor of the coolant temperature of the engine on fuel consumption is added, that is, the current coolant temperature of the engine is obtained, the torque correction coefficient is determined according to the current coolant temperature, and the target engine torque and the target motor torque are corrected by the torque correction coefficient to obtain the corrected engine torque and the corrected motor torque; the corrected motor torque is used as the execution torque of the motor, and the corrected engine torque is used as the execution torque of the engine, which can further reduce the energy consumption of the whole vehicle.

[0066] Although the present invention has been illustrated and described by referring to some preferred embodiments of the present invention, those of ordinary skill in the art should understand that the above content is a further detailed description of the present invention in combination with specific embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. Those skilled in the art can make various changes in form and details, including making several simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A torque distribution method for a hybrid vehicle, characterized in that, It includes the following steps: S1: Obtain the current driving condition parameters of the vehicle, and determine the current vehicle demand torque according to the current driving condition parameters and the torque characteristic map; wherein, the current driving condition parameters include the current throttle opening and the current vehicle speed, and the current vehicle demand torque includes the target engine torque and the target motor torque; S2: Obtain the current coolant temperature of the engine, and determine the execution torque of the motor and the execution torque of the engine according to the current coolant temperature, the target engine torque, and the target motor torque; wherein, If the current coolant temperature is less than or equal to the first temperature threshold, the engine is in a cold state; if the current coolant temperature is greater than or equal to the second temperature threshold, the engine is in a hot state; wherein, the second temperature threshold is greater than the first temperature threshold; when the engine is in the cold state or the hot state, the execution torque of the motor is the target motor torque, and the execution torque of the engine is the target engine torque; If the current coolant temperature is greater than the first temperature threshold and less than the second temperature threshold, the engine is in the warm-up stage. Determine the torque correction coefficient according to the current coolant temperature and the preset torque correction map, and correct the target motor torque and the target engine torque according to the torque correction coefficient to obtain the corrected engine torque and the corrected motor torque; the execution torque of the motor is the corrected motor torque, and the execution torque of the engine is the corrected engine torque.

2. The torque distribution method for a hybrid vehicle according to claim 1, characterized in that, If the engine is in the warm-up stage, perform the following steps: Determine the torque correction coefficient; wherein, When the target motor torque is a negative torque, determine the torque correction coefficient according to the current coolant temperature and the preset torque correction map; wherein, the torque correction coefficient is greater than or equal to 1; When the target motor torque is a positive torque or 0, the torque correction coefficient is 1; Correct the target motor torque according to the torque correction coefficient to obtain the corrected motor torque; Determine the corrected engine torque according to the current vehicle demand torque and the corrected motor torque.

3. The torque distribution method for a hybrid vehicle according to claim 2, characterized in that, If the engine is in the warm-up stage, the range of the torque correction coefficient when the target motor torque is a negative torque is 1 to 1.

5.

4. The torque distribution method for a hybrid vehicle according to claim 3, characterized in that, If the engine is in the warm-up stage, divide the warm-up stage into at least two sub-warm-up stages according to the preset coolant temperature threshold; wherein, the preset torque correction map includes at least two corresponding preset sub-torque correction maps, and the preset coolant temperature threshold is greater than the first temperature threshold and less than the second temperature threshold; When the target motor torque is a negative torque, determine the torque correction coefficient according to the current coolant temperature and the corresponding preset sub-torque correction map.

5. The torque distribution method for a hybrid vehicle according to any one of claims 1 - 4, characterized in that, The first temperature threshold is 35°C, and the second temperature threshold is 80°C.

6. The torque distribution method for a hybrid vehicle according to claim 5, characterized in that, The warm-up stage includes a first sub-warm-up stage and a second sub-warm-up stage; wherein, If the current coolant temperature is within the range of 35°C to 50°C, the engine is in the first sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.1 to 1.5; If the current coolant temperature is within the range of 50°C to 80°C, the engine is in the second sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1 to 1.

1.

7. The torque distribution method for a hybrid vehicle according to claim 6, characterized in that, The first sub-warm-up stage includes a first pre-sub-warm-up stage, a first mid-sub-warm-up stage, and a first post-sub-warm-up stage; among them, If the current coolant temperature is within the range of 35°C to 40°C, the engine is in the first pre-sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.2 to 1.5; If the current coolant temperature is within the range of 40°C to 42°C, the engine is in the first mid-sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.15 to 1.2; If the current coolant temperature is within the range of 42°C to 50°C, the engine is in the first post-sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.1 to 1.

15.

8. The torque distribution method for a hybrid vehicle according to claim 6, characterized in that, The second sub-warm-up stage includes a second pre-sub-warm-up stage and a second post-sub-warm-up stage; among them, If the current coolant temperature is within the range of 50°C to 60°C, the engine is in the second pre-sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1.05 to 1.1; If the current coolant temperature is within the range of 60°C to 80°C, the engine is in the second post-sub-warm-up stage, and the range of the torque correction coefficient when the target motor torque is negative torque is 1 to 1.05.

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