Patent Description:
In the field of hybrid electric vehicles related to the two-gear dedicated hybrid transmission (DHT), the vehicle can achieve switching between multiple operating modes, including a pure electric drive mode, a series drive mode and a hybrid drive mode that can achieve automatic switching. Automatic switching between drive modes can be realized through the control of a transmission control unit.

The vehicle control unit (VCU) determines the best operation mode of the vehicle according to the power demand of the driver for driving the vehicle and the state (vehicle speed, power of the traction battery and other factors) of the vehicle. Under the pure electric drive mode and the series drive mode, the engine and transmission are not directly involved in driving the vehicle, and the vehicle is only driven by the drive motor. Under the hybrid drive mode, the engine transmits power directly to the wheels through the transmission. Therefore, under the operating conditions of the pure electric drive mode or the series drive mode, if switching to the hybrid drive mode, it is necessary to perform the gear shifting of the synchronizer and the engagement of the clutch of the transmission.

While in the gear shifting of the synchronizer, it is necessary to has certain restrictions on the speed difference at both ends of the synchronizer, if the vehicle speed is higher, the synchronizer will directly perform the gear shifting at high speed, which will be impossible to complete due to excessive speed difference. That is to say, if the drive mode switching is required at high speed, it may not be realized due to the limitation of the ability of the synchronizer.

<CIT> discloses a control method for the acceleration process of a vehicle, a device and a hybrid electric vehicle. The control method comprises the following steps: acquiring an acceleration required torque when the vehicle is in a pure-electric driving state; controlling an engine to start if the acceleration required torque is greater than the maximum output torque of a driving motor; when the rotating speed of the engine reaches to the rotating speed required by a preset gear of a transmission, controlling a clutch to be closed, wherein the preset gear is the highest gear in gears provided by the transmission; acquiring a target gear according to the current speed of the vehicle, and when the rotating speed of the engine is increased to the rotating speed required by the target gear, controlling the gear of the transmission to be switched to the target gear.

<CIT> discloses a drive apparatus for a vehicle that includes a transmission including a transmission clutch that includes an input element, an output element, and an engagement element, a transmission drive mechanism, a clutch, a clutch drive mechanism, a motor generator, a clutch/motor torque increase portion controlling the transmission clutch to increase a clutch torque and increase a motor torque by an amount corresponding to the increase of the clutch torque in a case where an engine start request is obtained during a motor driving of the vehicle, a transmission drive mechanism biasing portion driving the transmission drive mechanism to bias the engagement element that is engaged in a release direction in a case where the clutch torque reaches an engine start request torque, and an engine combustion start portion starting a combustion of the engine in a case where a rotation speed of the engine reaches a predetermined value.

<CIT> describes a mode transition control device for hybrid vehicles that minimizes the discomfort a driver might feel when switching from series to parallel mode while driving. Specifically, during the transition between these modes in a hybrid vehicle, a gear shift stage is chosen to ensure that the change in rotational speed (NE) of the internal combustion engine (ICE) does not exceed a predefined threshold value (NE TH).

An object of the present invention is to provide a method and a device for controlling mode switching of a hybrid electric vehicle, and a vehicle, in order to solve the problem that the drive mode switching of vehicle in the existing related technologies may not be realized due to the limitation of the ability of the synchronizer.

In order to realize above-mentioned object, the present invention provides a method for controlling mode switching of a hybrid electric vehicle, and the method includes:.

In an embodiment, the method further includes:
performing, if the drive state information indicates that the current drive mode of the hybrid electric vehicle is the hybrid drive mode and a current speed of the hybrid electric vehicle is less than the speed limit, a reverse gear operation when the transmission gear of the hybrid electric vehicle is the second gear, to switch the transmission gear from the second gear to the neutral gear.

In an embodiment, the hybrid electric vehicle includes a transmission control unit and an electronic stability program, and the step of acquiring a current drive state information of the hybrid electric vehicle includes:.

In an embodiment, the hybrid electric vehicle includes a transmission control unit, an electronic stability program and synchronizer electrically connected with the transmission control unit, and the step of performing a pre-gear operation includes:
sending a pre-gear command to the transmission control unit, and the pre-gear command is configured to instruct the transmission control unit to control the synchronizer to perform the pre-gear operation.

In an embodiment, the method further includes:
re-sending the pre-gear command to the transmission control unit when a message indicative of failure of gear shifting sent by the transmission control unit in response to the pre-gear command is received.

In an embodiment, the speed limit is determined by:.

In an embodiment, the hybrid electric vehicle includes a transmission control unit and a clutch electrically connected with the transmission control unit; and the step of switching the hybrid electric vehicle from a non-hybrid drive mode to a hybrid drive mode includes:
sending a mode switching command to the transmission control unit, and the mode switching command is configured to instruct the transmission control unit to control an engagement of the clutch with an engine of the hybrid electric vehicle to complete an operation of switching from a pure electric drive mode or a series drive mode to a hybrid electric drive mode.

The present invention further provides a device for controlling mode switching of a hybrid electric vehicle, and the device includes:.

In an embodiment, the step of acquiring, through the acquisition module of the device, acurrent drive state information of the hybrid electric vehicle includes:.

In an embodiment, the step of performing, through the processing module of the device, a pre-gear operation includes:
sending a pre-gear command to the transmission control unit, wherein the pre-gear command is configured to instruct the transmission control unit to control the synchronizer to perform the pre-gear operation.

In an embodiment, the processing module is further configured for re-sending the pre-gear command to the transmission control unit when a message indicative of failure of gear shifting sent by thetransmission control unit in response to the pre-gear command is received.

In an embodiment, the step of switching, through the switching module,the hybrid electric vehiclefrom the non-hybrid drive mode to a hybrid drive mode includes:
sending a mode switching command to the transmission control unit, wherein the mode switching command is configured to instruct the transmission control unit to control an engagement of the clutch with an engine of the hybrid electric vehicle to complete an operation of switching from a pure electric drive mode or a series drive mode to a hybrid electric drive mode.

In an embodiment,the switching module is further configured for:
performing, if the drive state information indicates that the current drive mode of the hybrid electric vehicle is the hybrid drive mode and a current speed of the hybrid electric vehicle is less than the speed limit, a reverse gear operation when the transmission gear of the hybrid electric vehicle is the second gear, to switch the transmission gear from the second gear to the neutral gear.

The present invention provides a hybrid electric vehicle, and the hybrid electric vehicle includes a transmission control unit, an electronic stability program and a device for controlling mode switching electrically connected with the transmission control unit and the electronic stability program, and the device for controlling mode switching is configured for implementing the method for controlling mode switching of a hybrid electric vehicle mentioned above.

With the above technical solution, the following effects can be achieved at least:
Compared with the prior art, the vehicle control unit sends a mode switching command whendetecting that the vehicle needs to perform mode switching, the mode switching command is configured to indicate the gear shifting of the synchronizer and the engagement of the clutch of thetransmission control unit, after the gear shifting is successful, the drive mode of the vehicle is switched. However, the current vehicle speed may have exceeded the limitation of the speed difference at both ends of the synchronizer, which may cause the synchronizer to fail to engage a gear, therefore, the switching of vehicle operation mode fails.

When the vehicle reaches the standard value (that is, the above speed limit)of the system set based on the maximum speed difference acceptable to the synchronizer, the present invention sends a pre-gear command to control the transmission for pre-gear operating. In this way, when the vehicle is drivingat a high speed and the driving statusneeds to switch to the hybrid power mode, the mode switching action can be directly carried out without further gear shifting. The case that the failure of gear shifting caused by the limitation of the ability of the synchronizer is avoided, the normal mode switching when the vehicle is running at high speed is ensured, and the vehicle performance is improved.

The above-mentioned and/or additional aspects and advantages of the present invention will become apparent and easy to understand from the following description of embodiments in combination with the accompanying drawings, wherein:.

The specific embodiments of the present invention are described in detail below in combination with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain and interpret the invention and are not used to limit the invention.

In order to enable ordinary technicians in the art to quickly understand the improvement of the technical solution provided by the embodiments of the present invention compared with the prior art, the following first introduces the method for controlling mode switching of a hybrid electric vehicle in the relevant technology, in which the hybrid electric vehicle can be a hybrid vehicle equipped with a two-gear dedicated hybrid transmission (DHT).

The vehicle can realize switching between multiple operating modes, including a pure electric drive mode, a series drive mode and a hybrid drive mode. Each drive mode can be automatically switched through controller control to improve the power and economy of the vehicle.

The vehicle control unit (VCU) determines the best operation mode of the vehicle according to the power demand of the driver for driving the vehicle and the state (vehicle speed, power of the traction battery and other factors) of the vehicle. Under the pure electric drive mode and the series drive mode, the engine and transmission are not directly involved in driving the vehicle,and the vehicle is only driven by the drive motor. Under the hybrid drive mode, the engine transmits power directly to the wheels through the transmission. Therefore, under the operating conditions of the pure electric drive mode or the series drive mode, if switching to the hybrid drive mode,it is necessary to perform the gear shifting of the synchronizer and the engagement of the clutch of the transmission.

While in the gear shifting of the synchronizer, it is necessary tohas certain restrictions on the speed difference at both ends of the synchronizer, if the vehicle speed is higher, the synchronizer will directly perform the gear shifting at high speed, which will be impossible to complete due to excessive speed difference. That is to say, when the vehicle is driving at a highspeed, the vehicle isnot able to be switched to the hybrid drive mode due tolimitation of the ability of the synchronizer.

In order to solve the above technical problems, the embodiment of the present invention provides a method for controlling mode switching of a hybrid electric vehicle. For example, the method can be applied to the VCU of the hybrid electric vehicle, as shown in <FIG>. The method includes:
S11, acquiring a current drive state information of the hybrid electric vehicle.

The drive state information can include the drive modes of the current vehicle in the current gear, the gear information under the current drive mode, the current vehicle speed and the current vehicle demand power. The vehicle demand power can include the drive demand power and the demand power of electrical accessories. The drive demand power can be the electrical signal acquired by the vehicle control unit by converting the travel of the accelerator pedal and brake pedal, the drive demand power of the vehicle under the current working condition is calculated according to the electric signal; the demand power of electrical accessories can be determined by the vehicle control unit based on the working state of each electrical accessory on the vehicle.

S12, performing, if the drive state information indicates that a current drive mode of the hybrid electric vehicle is a forward mode of a non-hybrid drive and in a case that a current speed reaches a speed limit, a pre-gear operation when a transmission gear of the hybrid electric vehicle is a neutral gear, to switch the transmission gear from the neutral gear to a second gear.

Taking the two-gear DHT as an example, the transmission gears include a neutral gear, a first gear and a second gear. The above speed limit can be the speed value that is pre calibrated to match the second gear, that is, when the vehicle speed reaches the speed value, the transmission gear can be smoothly switched from neutral gear to second gear. In addition, the drive modes of the hybrid electric vehicle can include a hybrid drive mode, a series drive mode and a pure electric drive mode.

S <NUM>, switching, if the drive state information meets preset switching conditions of drive modes, the hybrid electric vehicle from the non-hybrid drive mode to a hybrid drive mode when the transmission gear of the hybrid electric vehicle is the second gear. The switching conditionsof preset drive modes can be that when the vehicle speed increases to a certain range, the driver does not need strong power, and the conditions of engine operation and economic zone are just meet.

That is, the technical solution of the embodiment of the present invention adds a speed limit for the condition of controlling mode switching, so that the vehicle can perform the pre-gear operation when the vehicle reaches the speed limit, and when the vehicle speed is higher than the speed limit and the vehicle is necessary to switch to the hybrid power drive mode, the synchronizer has been in gear, and the clutch can be directly engaged, Thus, the failure of mode switching caused by the inability to engage a gear will not occur due to the limitation of the ability of the synchronizer. , and the power performance and economy of the vehicle are effectively improved.

In an embodiment, on the basis of the method shown in <FIG>, the step of acquiring a current drive state information of the hybrid electric vehicle includes:.

In an embodiment, the step of performing a pre-gear operation includes:
sending a pre-gear command to the transmission control unit, and the pre-gear command is configured to instruct the transmission control unit to control the synchronizer to perform the pre-gear operation.

In an embodiment, when a message indicative of failure of gear shifting sent by the transmission control unit in response to the pre-gear command is received, the pre-gear command to the transmission control unit is re-sent. Therefore, the gear operation can be re-performed in a timely manner in case of a gear failure to avoid mode switching failure.

In an embodiment, the step of switching the hybrid electric vehiclefrom the non-hybrid drive mode to a hybrid drive mode includes:
sending a mode switching command to the transmission control unit, and the mode switching command is configured to instruct the transmission control unit to control an engagement of the clutch with an engine of the hybrid electric vehicle to complete an operation of switching from a pure electric drive mode or a series drive mode to a hybrid electric drive mode.

In order for those skilled in the art to further understand the method for controlling mode switching provided by the embodiments of the present invention, the method for controlling mode switching of a hybrid electric vehicle in the embodiments of the present invention is described in detail below:
<FIG> is another flow chart of a method for controlling mode switching provided by the embodiment of the present invention, as shown in the <FIG>, which includes:.

During specific implementation, the conditions for performing reverse gear can be as follows: the drivestate information indicates that the current drive mode of the hybrid electric vehicle is hybrid drive mode, and the current speed of the hybrid electric vehicle is less than the speed limit of the vehicle and keeps for <NUM> seconds. In which, the <NUM> seconds can be a manually set time, which is not limited in the embodiments of the present invention.

With the above method, when the current vehicle speed of the vehicle is less than the speed limit of the vehicle, the transmission gear can be returned to the neutral gear, which prevents the vehicle from switching to hybrid drive modewhen driving at low speed, while thetransmission gear of the vehicle is still at a high gear. The engineis easy to generate carbon deposits when the vehicle is driving at a high gear and low speed, which is conducive to the service life of the engine.

<FIG> is a yet flow chart of a method for controlling mode switching provided by the embodiment of the present invention, in which the speed limit is set to <NUM> kph (km/h), the hybrid electric vehicle is a hybrid electric vehicle equipped with a two-gear DHT, and the vehicle has three drive modes, including a pure electric drive mode, a series drive mode, and a hybrid drive mode. In which, the VCU represents the vehicle control unit, the TCU represents the transmission control unit, and D-gear represents that the vehicle is in forward gear.

According to steps S300, S301, S302, S303, S304, S305, S306, S307, S308, and S309 shown in <FIG>, when the vehicle is successfully engaged a gear, if the vehicle drive state does not meet the conditions for switching to hybrid drive mode and the vehicle speed is below 105kph for more than <NUM> seconds, the transmission gear will return to neutral gear, whichprevents the vehicle from switching to hybrid drive mode when driving at low speed, while the transmission gear of the vehicle is still at a high gear. The engine is easy to generate carbon deposits when the vehicle is driving at a high gear and low speed, which is conducive to the service life of the engine.

According to steps S300, S301, S302, S303, S304, S305, S306, S307, S310, S311, S312, S313, S314, S315, and S316shown in <FIG>, when the current vehicle speed is greater than the preset speed limit, the current vehicle drive mode is the series drive mode or the pure electric drive mode and the current vehicle is in a forward gear,the vehicle controller sends a pre-gear request, and the transmission control unit receives the pre-gear request and executes the pre-gear request, If the drive state of the vehicle meets the conditions for switching to the hybrid drive mode after successful gear shifting, the vehicle control unit sends the mode switching command, and the transmission control unit receives and executes the mode switchingcommand. The whole mode switching process is ended after successful switching. It also includes the feedback mechanism of steps S304, S305, S312 and S313 to ensure that the pre-gear request and drive mode switching request sent by the vehicle control unit are fully implemented.

Based on the same inventive concept, the embodiments of the present invention further provides a device <NUM> for controlling mode switching of a hybrid electric vehicle, which is used to implement the steps of the method for controlling mode switching provided by the above method embodiments. The device <NUM> for controlling mode switching can realize the vehicle control unit on the hybrid electric vehicle in software, hardware or a combination of both. As shown in <FIG>, the device <NUM> includes:.

With the above device <NUM> for controlling mode switching, the present invention is provided with a speed limit, except that the transmission gear is shifted from the neutral gear to a higher gear when the mode is switched to the hybrid mode. When the vehicle speed reaches the speed limit, the vehicle control unit sends out a pre-gear command, and the synchronizer is shifted from the neutral gear to the second gear. After the gear shifting is completed, if the drive demand of the vehicle meets the conditions for switching to the hybrid drive mode, the mode switching can be completed without controlling the synchronizer to shift the gear only by engaging the clutch, which avoids the mode switching being blocked due to the limitation of the ability of the synchronizer during the mode switching and synchronizer engaging when the vehicle speed is too high, which can not only meet the driving needs of the driver, but also improve the use economy of the vehicle as much as possible.

In an embodiment, the step of acquiring, through the acquisition module <NUM>, a current drive state information of the hybrid electric vehicle includes:.

In an embodiment, the step of performing, through the processing module <NUM>, a pre-gear operation includes:
sending a pre-gear command to the transmission control unit, the pre-gear command is configured to instruct the transmission control unit to control the synchronizer to perform the pre-gear operation.

In an embodiment, the processing module <NUM> is further configured for re-sending the pre-gear command to the transmission control unit when a message indicative of failure of gear shifting sent by the transmission control unit in response to the pre-gear command is received.

In an embodiment, the speed limit of the vehicle with the device <NUM> is determined by:.

In an embodiment, the step of switching, through the switching module <NUM>,the hybrid electric vehicle from the non-hybrid drive mode to a hybrid drive mode includes:
sending a mode switching command to the transmission control unit, and the mode switching command is configured to instruct the transmission control unit to control an engagement of the clutch with an engine of the hybrid electric vehicle to complete an operation of switching from apure electric drive mode or a series drive mode to a hybrid electric drive mode.

In an embodiment, the switching module <NUM> is further configured for:
performing, if the drive state information indicates that the current drive mode of the hybrid electric vehicle is the hybrid drive mode and a current speed of the hybrid electric vehicle is less than the speed limit, a reverse gear operation when the transmission gear of the hybrid electric vehicle is the second gear, to switch the transmission gear from the second gear to the neutral gear.

Claim 1:
A method for controlling mode switching of a hybrid electric vehicle, comprising:
acquiring a current drive state information of the hybrid electric vehicle;
characterized in that performing, if the drive state information indicates that a current drive mode of the hybrid electric vehicle is a forward mode of a non-hybrid drive and in a case that a current speed reaches a speed limit, a pre-gear operation when a transmission gear of the hybrid electric vehicle is a neutral gear, to switch the transmission gear from the neutral gear to a second gear; and
switching, if the drive state information meets preset switching conditions of drive modes, the hybrid electric vehicle from the non-hybrid drive mode to a hybrid drive mode when the transmission gear of the hybrid electric vehicle is the second gear,
wherein performing, if the drive state information indicates that the current drive mode of the hybrid electric vehicle is the hybrid drive mode and a current speed of the hybrid electric vehicle is less than the speed limit, a reverse gear operation when the transmission gear of the hybrid electric vehicle is the second gear, to switch the transmission gear from the second gear to the neutral gear.