Control system for vehicle
阅读说明:本技术 用于车辆的控制系统 (Control system for vehicle ) 是由 马修·汉科克 于 2019-02-25 设计创作,主要内容包括:本公开涉及一种用于车辆的缓行速度控制系统,该车辆具有用于向至少一个车轮提供转矩的至少一个电动马达。该系统包括:输入端,该输入端配置成接收指示车辆的当前速度的当前速度信号;缓行速度控制模块,该缓行速度控制模块配置成当车辆的当前速度经过高于缓行速度目标值的预定阈值时启用;以及输出端,该输出端配置成在缓行速度控制模块启用时,向所述至少一个电动马达发送缓行速度控制转矩信号,以根据缓行速度目标值控制车辆速度,其中,该缓行速度控制转矩信号被限制为小于缓行速度控制最大转矩值的缓行速度控制过滤的转矩值。(The present disclosure relates to a creep speed control system for a vehicle having at least one electric motor for providing torque to at least one wheel. The system comprises: an input configured to receive a current speed signal indicative of a current speed of a vehicle; a creep speed control module configured to be activated when a current speed of the vehicle passes a predetermined threshold above a creep speed target value; and an output configured to send a creep speed control torque signal to the at least one electric motor to control the vehicle speed according to a creep speed target value when the creep speed control module is enabled, wherein the creep speed control torque signal is limited to a creep speed control filtered torque value that is less than a creep speed control maximum torque value.)
1. A creep speed control system for a vehicle having at least one electric motor for providing torque to at least one wheel, the system comprising:
an input configured to receive a current speed signal indicative of a current speed of the vehicle;
a creep speed control module configured to be enabled when the current speed of the vehicle passes a predetermined threshold above a creep speed target value; and
an output configured to send a creep speed control torque signal to the at least one electric motor to control vehicle speed according to the creep speed target value after the creep speed control module is enabled,
wherein the creep speed control torque signal is limited to a creep speed control filtered torque value that is less than a creep speed control maximum torque value, and
wherein the creep speed control torque signal is limited to the creep speed control filtered torque value during a torque reversal phase of a driveline of the vehicle.
2. The system of claim 1, wherein the creep speed control filtered torque value becomes equal to the speed control maximum torque value throughout a prescribed filtering period after the creep speed control module is enabled.
3. A system according to any preceding claim, wherein the creep speed control filtered torque value is variable over time.
4. The system of claim 3, wherein the creep speed control filtered torque value increases over time.
5. The system of claim 4, wherein the creep speed control filtered torque value increases at a constant rate.
6. The system of any of claims 3 to 5, wherein the creep speed control filtered torque value increases at a first rate for a first prescribed filtering period less than the entire prescribed filtering period after the creep speed control module is enabled.
7. The system of claim 6, wherein the creep speed control filtered torque value increases at a second rate, the second rate being greater than the first rate, for a second prescribed filtering period after the first prescribed filtering period.
8. A system according to claim 6 or claim 7, wherein the creep speed control filtered torque value in the first prescribed filtering period is less than the speed control torque value required to maintain the vehicle speed at the creep speed target value.
9. The system of any preceding claim, wherein the creep speed control filtered torque value is zero when the creep speed control module is enabled.
10. The system of any preceding claim, wherein the creep speed control module is configured to deactivate when a driver demanded torque is non-zero and the vehicle speed is greater than the creep speed target value.
11. A system according to any preceding claim, wherein the creep speed control module is selectively operable by a driver of the vehicle.
12. A creep speed control method for a vehicle having at least one electric motor providing torque to at least one wheel, the method comprising,
receiving a current speed signal indicative of a current speed of the vehicle;
enabling a creep speed control module when the current speed of the vehicle passes a predetermined threshold creep speed that is above a creep speed target value; and
sending a creep speed control torque signal to the at least one electric motor to control vehicle speed according to the creep speed target value after the creep speed control module is enabled,
wherein the creep speed control torque signal is limited to a creep speed control filtered torque value that is less than a creep speed control maximum torque value, and
wherein the creep speed control torque signal is limited to the creep speed control filtered torque value during a torque reversal phase of a driveline of the vehicle.
13. A vehicle comprising a system according to any one of claims 1 to 11 or configured to perform a method according to claim 12, optionally wherein the vehicle is a purely electric vehicle.
14. The vehicle of claim 13, comprising a first electric motor providing torque to at least one front wheel of the vehicle and a second electric motor providing torque to at least one rear wheel of the vehicle.
15. A non-transitory, computer-readable storage medium having stored thereon instructions which, when executed by one or more processors, cause the one or more processors to implement the method of claim 12.
Technical Field
The present disclosure relates to control systems for vehicles and in particular, but not exclusively, to creep speed control systems for vehicles. Aspects of the invention relate to systems, methods, vehicles, and computer-readable storage media.
Background
Many vehicles, such as automobiles, with automatic transmissions include a so-called "creep speed" function or idle function that maintains the vehicle at a relatively low speed, such as 6km/h, when the vehicle driver is not depressing the accelerator pedal or brake pedal. In such vehicles, the automatic transmission includes a fluid coupling or a slip clutch that connects the output of the internal combustion engine to the wheels of the vehicle. Creep speed is dependent on engine idle speed and the transmission ratio of the transmission. Creep may be particularly useful in situations where the driver needs to stop and start the vehicle multiple times, such as in the case of traffic congestion. The creep function enables the driver to control the movement of the vehicle using only the brake pedal, i.e. depressing the brake pedal to stop the vehicle and moving their foot away from the brake pedal to allow slow movement of the vehicle in a forward or backward direction.
In vehicles that use one or more electric motors instead of an internal combustion engine to provide drive torque to the wheels, such as electric-only vehicles (BEVs), there is no built-in creep speed function. Unlike a vehicle having an internal combustion engine, in a vehicle having an internal combustion engine, the engine continues to rotate at idle speed when the driver does not request any drive torque or brake torque via the accelerator pedal and brake pedal; in a purely electric vehicle, the electric motor does not provide torque to the wheels in this case.
It is desirable that the driver of a purely electric vehicle be able to obtain a creep speed function that mimics the creep function of a conventional automotive vehicle. However, for purely electric vehicles, there are difficulties in entering such creep mode in some cases. Especially in purely electric vehicles, where the electric motor is permanently connected or directly connected to the wheels, i.e. without a slip clutch. This may be problematic in case the torque of the electric motor or machine has to be switched from a negative value to a positive value. In particular, in this case, it is possible for so-called "kickback" (backslash) or thumping and then vibration to occur in the drive train, which may result in driver discomfort and damage to the drive train. Specifically, gears in the drive train must transition from meshing in one direction to meshing in the opposite direction. For example, this situation may occur in a situation where the driver releases the accelerator pedal relatively suddenly when driving at a medium to high speed, such as 50km/h, i.e. the direction of engagement of the gears changes too quickly.
The object of the present disclosure is to address the disadvantages associated with the prior art.
Disclosure of Invention
According to an aspect of the invention, a creep speed control system for a vehicle having at least one electric motor for providing torque to at least one wheel is provided. The system includes an input configured to receive a current speed signal indicative of a current speed of the vehicle. The system also includes a creep speed control module configured to activate when a current speed of the vehicle passes a predetermined threshold above a creep speed target value. The system also includes an output configured to send a creep speed control torque signal to the at least one electric motor to control the vehicle speed according to a creep speed target value after the creep speed control module is enabled. The creep speed control torque signal is limited to a creep speed control filtered torque value that is less than the creep speed control maximum torque value.
Advantageously, the creep speed control system provides a creep speed function in a vehicle powered by one or more motors rather than an internal combustion engine. Thus, the creep speed function of a conventional automatic vehicle can be simulated in an electric vehicle, thereby giving the driver a more familiar feeling when controlling the motion of the vehicle in slow moving traffic, for example. Further, limiting the torque requested from the electric motor may enable a more gradual change in motor torque from negative to positive to occur, for example, during a creep mode entry. The ability to filter the value of maximum allowable torque that may be requested at the motor by the creep speed control module thus enables entry into the creep mode to be controlled, thereby reducing or eliminating backlash in the drive train. Thus, a creep speed control system is provided that provides comfortable creep access to the driver and prevents potential damage to the driveline. In addition, the creep speed control module "knows" the filtering via the creep speed control filtered torque. This means that there is no integrator tail downstream of the creep speed control module and no filtering, which means that the control module is not unstable.
The creep speed control torque signal may be limited to a creep speed control filtered torque value during a torque reversal phase of the vehicle driveline. This is the time period or phase during which the kickback effect is most likely to be severe or likely to occur.
The creep speed control filtered torque value may become equal to the speed control maximum torque value for the entire prescribed filtering period after the creep speed control module is enabled. That is, once the filtering period has elapsed, the possibility of occurrence of kickback becomes negligible, and therefore it is not necessary to continue limiting the maximum allowable requested torque below the creep speed control maximum torque value.
The creep speed control filtered torque value may vary over time.
The creep speed control filtered torque value may increase over time.
The creep speed control filtered torque value may be increased at a constant rate.
The creep speed control filtered torque value may be increased at a first rate for a first prescribed filtering period less than the entire prescribed filtering period after the creep speed control module is enabled.
The creep speed control filtered torque value may be increased at a second rate for a second prescribed filtering period subsequent to the first prescribed filtering period, the second rate being greater than the first rate.
The creep speed control filtered torque value in the first prescribed filtering period may be less than the speed control torque value required to maintain the vehicle speed at the creep speed target value.
During the first prescribed filtering period, the creep speed control torque signal, i.e., the rate at which the requested motor torque increases after activation of the creep speed control module, is limited to prevent kickback during the torque reversal phase. In the second prescribed filtering period, the rate at which the creep speed control torque signal is increased is still limited, but to a lesser extent than in the first filtering period. Thus, the first and second prescribed filtering periods provide the benefit of preventing kickback in the vehicle driveline while still allowing the vehicle to reach the target creep speed without significant hysteresis that could inconvenience the driver. That is, speed control performance, i.e., the ability to maintain the creep speed target value, is not compromised.
The creep speed control filtered torque value may be zero when the creep speed control module is enabled.
The creep speed control module may be configured to deactivate when the driver demand torque is non-zero and the vehicle speed is greater than the creep speed target value.
The creep speed control module may be selectively operable by a driver of the vehicle.
According to another aspect of the present invention, a creep speed control method for a vehicle having at least one electric motor for providing torque to at least one wheel is provided. The method includes receiving a current speed signal indicative of a current speed of the vehicle. The method also includes enabling the creep speed control module when a current speed of the vehicle passes a predetermined threshold above a creep speed target value. The method also includes sending a creep speed control torque signal to the at least one electric motor to control the vehicle speed according to the creep speed target value after the creep speed control module is enabled. The creep speed control torque signal is limited to a creep speed control filtered torque value that is less than the creep speed control maximum torque value.
According to another aspect of the invention, a vehicle is provided, comprising a system as described above or configured to perform a method as described above.
The vehicle may be a purely electric vehicle.
The vehicle may include a first electric motor that provides torque to at least one front wheel of the vehicle and a second electric motor that provides torque to at least one rear wheel of the vehicle.
According to another aspect of the invention, there is provided a non-transitory computer-readable storage medium having stored thereon instructions which, when executed by one or more processors, may cause the one or more processors to perform the above-described method.
It is expressly intended within the scope of the present application that the various aspects, embodiments, examples and alternatives set forth in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the various features thereof, may be employed individually or in any combination. That is, features of all embodiments and/or any embodiments may be combined in any manner and/or combination unless such features are incompatible. The applicant reserves the right to amend any originally filed claim or to file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim, even if not initially claimed in such a way.
Drawings
One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic illustration of a powertrain for a full electric vehicle (BEV) including a creep speed control system, according to an embodiment of an aspect of the present invention;
FIG. 2 is a more detailed schematic diagram of the creep speed control system of FIG. 1;
FIG. 3 is a schematic illustration of speed and torque of a vehicle controlled by the creep speed control system of FIG. 2 with respect to time;
FIG. 4 is a schematic illustration of a purely electric vehicle including the creep speed control system of FIG. 1; and
FIG. 5 illustrates steps of a method performed by the creep speed control system of FIG. 1, according to an embodiment of an aspect of the present invention.
Detailed Description
FIG. 1 is a schematic illustration of a
The vehicle 60 has a creep speed control system or
The creep
In particular, in the first case described above, entering into creep mode may result in so-called "kickback" in the drive train. During creep from this "overrun" condition, the torque of the
While decelerating, the vehicle 60 will eventually reach the upper limit of the predetermined threshold creep speed range. At this time, the creep speed mode is enabled. During creep, when the vehicle 60 is in forward gear, the requested torque in the drive trains 17, 19 is positive due to the
In a conventional automatic vehicle with an automatic transmission, gears within the driveline also change from meshing in one direction to meshing in the opposite direction during torque reversals. However, in conventional automotive vehicles, a fluid coupling or slip clutch between the internal combustion engine and the wheels may produce a damping effect in order to reduce the effect of backlash. In conventional autonomous vehicles with a slipping clutch, the drivability control function may apply a rate limit or filter to slow the torque request when it crosses zero requested torque, thereby preventing a thump.
In contrast, in the pure electric vehicle 60 of the present embodiment, the
Creep
Fig. 2 shows the functional components of the creep
The current speed 30 of the vehicle 60 is received at an input 31 of the
If the current vehicle speed 30 is within the threshold of the target creep speed, an enable
The
The
The
The filtered
The creep
The
Fig. 3a and 3b show schematic diagrams of how vehicle speed and motor torque change over time in a vehicle 60 having a creep
Fig. 3a shows how the current vehicle speed 30 varies over time, showing the creep speed target value 52 as a horizontal dashed line. Fig. 3a also shows an upper limit 52a and a lower limit 52b of the predetermined creep speed threshold range. The vehicle 60 is initially traveling at a speed greater than the upper limit 52a and is decelerating. The vehicle speed 30 eventually decelerates to a speed corresponding to the upper limit 52 a. When the
Fig. 3b shows motor torque 54 over time, which corresponds to vehicle speed 30 in fig. 3 a. Graph 3b shows an example of a change in torque 54 at one or both of the
Referring to fig. 3b, when the vehicle 60 is decelerating, the requested motor torque 54 is a negative value, i.e., an overspeed torque. As the vehicle speed 30 decreases, the requested torque 54 approaches zero. This coincides with the time that the vehicle speed 30 is equal to the creep speed target value 52. When the vehicle speed is equal to the upper limit 52a, the
The dashed
When the requested torque 54 is negative, the filtered
After the first filtering period 56, a second filtering period 58 is shown, during which second filtering period 58 the creep control filtered
FIG. 4 is a schematic illustration of a vehicle 60 including a creep
The creep
Fig. 5 shows the steps of a method 70 performed by the creep
Many modifications may be made to the examples described above without departing from the scope of the present invention, as defined in the following claims.
In the above embodiment, the vehicle 60 has two
In the above embodiment, the creep function is activated when the vehicle speed is within a predetermined threshold range; however, in a different embodiment, the creep function may be enabled when the vehicle speed reaches a predetermined (target) threshold creep speed.
In the above embodiment, the creep control filtered
In the above embodiment, there are two filtering periods 56, 58 during which the creep control filtered