car

Abstract

To enable an automobile to be stopped at a target position more surely.SOLUTION: An automobile comprises an engine and a control device that performs brake control with respect to driving force based on a rotation speed of the engine when parking the automobile automatically using power from the engine. The control device calculates, as a read-ahead rotation speed, a rotation speed of the engine estimated after a predetermined period of time has elapsed, and sets the read-ahead rotation speed as a rotation speed for calculation for calculating the driving force / power, when the read-ahead rotation speed is above an actual rotation speed of the engine, and sets the actual rotation speed as the rotation speed for calculation, when the read-ahead rotation speed is less than the actual rotation speed.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a vehicle, and more particularly to a vehicle in which brake control is performed on a driving force based on the engine speed when automatic parking is performed using power from the engine. [Background technology]

[0002] Conventionally, for this type of automobile, a vehicle driving control has been proposed that controls the driving force and braking force to automatically move the vehicle to a target position (see Patent Document 1). In this automobile, during the vehicle driving control, a control is also performed to increase the braking force when the idling speed of the engine increases and the driving force increases, and to decrease the braking force when the idling speed decreases and the driving force decreases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-25994 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned automobile, the driving force increases or decreases immediately in response to an increase or decrease in the idling speed of the engine, but the increase or decrease in the braking force may lag behind the increase or decrease in the driving force in response to an increase or decrease in the idling speed of the engine. Since the increase or decrease in the engine speed is detected and then the braking force is increased or decreased by the operation of an actuator for applying a braking force such as hydraulic pressure, the increase or decrease in the braking force is delayed from the increase or decrease in the driving force by the time required for the actuator to operate. Such a delay in the increase or decrease in the braking force in response to an increase or decrease in the driving force may hinder stopping at the target position depending on the timing of the increase or decrease in the engine speed.

[0005] The main object of the automobile of the present invention is to more reliably stop the automobile at a target position. [Means for solving the problem]

[0006] The automobile of the present invention employs the following means to achieve the above-mentioned main object.

[0007] The automobile of the present invention comprises: An automobile including an engine and a control device that performs brake control on a driving force based on a rotation speed of the engine when performing automatic parking using power from the engine, the control device calculates a rotation speed of the engine estimated after a predetermined period of time as a look-ahead rotation speed, and when the look-ahead rotation speed is equal to or greater than an actual rotation speed of the engine, the look-ahead rotation speed is used as a calculation rotation speed for calculating the driving force, and when the look-ahead rotation speed is less than the actual rotation speed, the actual rotation speed is used as the calculation rotation speed. It is characterized by:

[0008] In the automobile of the present invention, the engine revolution speed estimated after a predetermined period is calculated as the look-ahead revolution speed, and when the look-ahead revolution speed is equal to or greater than the actual engine revolution speed, the look-ahead revolution speed is used as the calculation revolution speed for calculating the driving force. Therefore, the engine revolution speed estimated after a predetermined period can be used to calculate the braking force application, and the delay in the increase in the braking force relative to the increase in the driving force can be suppressed. In addition, when the look-ahead revolution speed is less than the actual revolution speed, the actual revolution speed is used as the calculation revolution speed. This makes it possible to suppress the braking force from being too small when the actual revolution speed becomes equal to or greater than the look-ahead revolution speed due to a sudden change in the actual revolution speed. As a result, the vehicle can be stopped more reliably at the target position. The predetermined period is the time required for the braking force to be applied by the brake control based on the calculation revolution speed, and a time obtained by experiment or the like can be used. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an outline of the configuration of an automobile 20 according to an embodiment of the present invention. [Diagram 2]1 is an explanatory diagram showing an example of a state in which a hybrid vehicle 20 of the embodiment is automatically parked in a target parking space 100. FIG. [Diagram 3] 4 is a flowchart showing an example of a rotation speed setting process for automatic parking calculation executed by the electronic control unit 30. [Figure 4] 1 is an explanatory diagram showing an example of time changes of a target rotation speed Ne*, an actual rotation speed Ne, and a look-ahead rotation speed Nea. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Next, a mode for carrying out the present invention will be described using examples. EXAMPLES

[0011] FIG. 1 is a diagram showing an outline of the configuration of an automobile 20 as one embodiment of the present invention. As shown, the automobile 20 includes an engine 22, an automatic transmission 24, a braking device 26, a steering device 28, and an electronic control unit 30.

[0012] The engine 22 is configured as an internal combustion engine driven by a hydrocarbon fuel such as gasoline or diesel, and its output shaft is connected to the input shaft of an automatic transmission 24. The engine 22 is driven and controlled by an engine electronic control unit (hereinafter referred to as engine ECU) 23. Although not shown, the engine ECU 23 is configured as a microprocessor centered on a CPU, and in addition to the CPU, includes a ROM for storing processing programs, a RAM for temporarily storing data, an input / output port, and a communication port. Signals from various sensors required for controlling the operation of the engine 22 are input to the engine ECU 23 via the input port. Examples of signals input to the engine ECU 23 include a crank angle θcr from a crank position sensor that detects the rotational position of the crankshaft of the engine 22, and a cooling water temperature Tw from a water temperature sensor that detects the temperature of the cooling water of the engine 22. Other examples include an intake pressure Pi from an intake pressure sensor that detects the intake pressure of the engine 22, and an intake air amount Qa from an air flow meter that detects the intake air amount of the engine 22. The engine ECU 23 outputs, via an output port, various control signals for controlling the operation of the engine 22. The engine ECU 24 calculates the rotation speed Ne of the engine 22 based on the crank angle θc from the crank position sensor. The engine ECU 23 communicates with the electronic control unit 30 via a communication port.

[0013] The automatic transmission 24 is configured as a hydraulically driven transmission with six forward gears and one reverse gear, for example, consisting of a torque converter and an automatic transmission, and its drive shaft as an output shaft is connected to drive wheels 29a, 29b via a differential gear 29. The automatic transmission 24 is driven and controlled by an automatic transmission electronic control unit (hereinafter referred to as ATECU) 25. Although not shown, the ATECU 25 is configured as a microprocessor centered on a CPU, and in addition to the CPU, it is equipped with a ROM for storing processing programs, a RAM for temporarily storing data, an input / output port, and a communication port. The ATECU 25 performs gear shift control by turning on and off multiple clutches and brakes in a hydraulic circuit as actuators of the automatic transmission 24. The ATECU 25 communicates with an electronic control unit 30 via the communication port.

[0014] The brake device 26 is configured as a well-known hydraulically driven brake device, and is configured to provide braking force resulting from the brake depression force exerted by depressing a brake pedal 48 and braking force resulting from hydraulic pressure adjustment. The brake device 26 is driven and controlled by a brake electronic control unit (hereinafter referred to as brake ECU) 27, which also controls the braking force resulting from hydraulic pressure adjustment. The brake ECU 27 communicates with the electronic control unit 30 via a communication port.

[0015] The steering device 28 is mechanically connected to a steering wheel (not shown) and drive wheels 29a, 29b via a steering shaft, and is equipped with a steering actuator. The steering device 28 steers based on the driver's operation, and steers the drive wheels 29a, 29b by driving the actuator based on a steering signal from the electronic control unit 30.

[0016] The electronic control unit 30 is configured as a microprocessor centered around a CPU 31, and in addition to the CPU 31, it is equipped with a ROM 32 that stores processing programs, a RAM 33 that temporarily stores data, a flash memory 34, and input / output ports and communication ports (not shown).

[0017] Signals from various sensors are input to the electronic control unit 30 via input ports. Examples of signals input to the electronic control unit 30 include an ignition signal from an ignition switch 40, a vehicle speed V from a vehicle speed sensor 41, each wheel speed from a wheel speed sensor 42, an acceleration α from an acceleration sensor 43, a yaw rate signal from a yaw rate sensor 44, and a road surface gradient θ from a gradient sensor 45. Other examples of signals input to the electronic control unit 30 include an accelerator opening Acc from an accelerator pedal position sensor 47 that detects the amount of depression of an accelerator pedal 46, and a brake pedal position BP from a brake pedal position sensor 49 that detects the amount of depression of a brake pedal 48.

[0018] Various control signals are output from the electronic control unit 30 via the output port. Examples of the control signals output from the electronic control unit 30 via the output port include a display control signal to the display device 70, a communication control signal to the communication device 72, and an air conditioning control signal to the air conditioning device 74. As described above, the electronic control unit 30 is connected to the engine ECU 23, the ATECU 25, the brake ECU 27, and the like via the communication port. The electronic control unit 30 also communicates with a shift electronic control unit (hereinafter referred to as a shift ECU) 50, a surroundings recognition electronic control unit (hereinafter referred to as a surroundings recognition ECU) 55, and a navigation device 60 via the communication port.

[0019] Although not shown, the shift ECU 50 is configured as a microprocessor centered on a CPU, and in addition to the CPU, includes a ROM for storing processing programs, a RAM for temporarily storing data, an input / output port, and a communication port. A shift position signal from a shift position sensor 52 that detects the operation position of a shift lever 51 is input to the shift ECU 50 via an input port. The shift positions include a parking position (P range), a neutral position (N range), a drive position (D range), and a reverse position (R range). The shift ECU 50 is connected to the electronic control unit 30 and a surrounding recognition ECU 94 via a communication port, and sets the shift position based on the shift position signal from the shift position sensor 52 and a control signal from the surrounding recognition ECU 55, and transmits the set shift position to the electronic control unit 30.

[0020] Although not shown, the surrounding recognition ECU 55 is configured as a microprocessor centered on a CPU, and in addition to the CPU, it is provided with a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port. Information on the vehicle and its surroundings from the surrounding recognition device 56 (for example, the vehicle distances D1 and D2 between the vehicle and other vehicles in front and behind the vehicle, and the vehicle's running position in the lane on the road surface, etc.) is input to the surrounding recognition ECU 55 via an input port. Examples of the surrounding recognition device 56 include a camera, a millimeter wave radar, a quasi-millimeter wave radar, an infrared laser radar, and a sonar. Examples of the surrounding recognition device 56 include an automatic driving mode switch signal from an automatic driving switch 57 that sets the automatic driving mode, and an automatic parking switch signal from an automatic parking switch 58 that is operated when performing automatic parking. The automatic driving switch 57 and the automatic parking switch 58 are attached to the steering wheel or the installation panel in front of the driver's seat or in the vicinity thereof. As described above, the surrounding recognition ECU 55 is connected to the electronic control unit 30 and the shift ECU 90 via a communication port.

[0021] The navigation device 60 includes a main body 62 having a built-in controller having a storage medium such as a hard disk on which map information and the like is stored, an input / output port, and a communication port, a GPS antenna 64 for receiving information on the current location of the vehicle, and a touch panel display 66 for displaying various information such as information on the current location of the vehicle and a planned driving route to a destination, and allowing a user to input various instructions. Here, the map information includes service information (e.g., tourist information, parking lots, etc.) and road information for each driving section (e.g., between traffic lights and between intersections, etc.) stored as a database. The road information includes distance information, road width information, number of lanes information, area information (urban area or suburban area), type information (general road or expressway), gradient information, legal speed limit, number of traffic lights, turning radius of each curve, etc. When a destination is set by a user operating the display 66, the main body 62 of the navigation device 60 sets a planned driving route from the current location of the vehicle to the destination based on the map information stored in the main body 62 and the current location and destination of the vehicle obtained from the GPS antenna 64, and displays the set planned driving route on the display 66 to provide route guidance.

[0022] The automobile 20 of this embodiment thus configured can run in an automatic driving mode by turning on the automatic driving switch 57, and can automatically park by turning on the automatic parking switch 58.

[0023] In the autonomous driving mode, the electronic control unit 30 controls the vehicle speed V by controlling the engine 22, the automatic transmission 24, and the brake device 26 based on the planned driving route, the vehicle's current location, and map information (e.g., legal speed limits) from the navigation device 60, and information about the vehicle and its surroundings from the surrounding recognition device 56, and controls the steering device 28 to maintain the lane, change lanes, etc.

[0024] Automatic parking based on the operation of the automatic parking switch 88 is executed, for example, when the automatic parking switch 58 is operated while the brake pedal 48 is depressed and the vehicle is stopped, and the shift position SP is in the D range. An example of a state in which the automobile 20 of the embodiment is automatically parked in the target parking space 100 is shown in FIG. 2. Automatic parking is performed as follows. First, the driver sets the hatched parking space recognized by the surrounding recognition device 56 and displayed on the display 66 as the target parking space 100, and sets the parking orientation to park the automobile 20 backwards or forwards in the target parking space 100. FIG. 2 shows a case in which the automobile 20 is parked backwards. Next, when the target parking space 100 and the parking orientation are set, the target routes L1, L2 for parking the automobile 20 in the target parking space 100 are set. Then, the shift position SP, the engine 22, the automatic transmission 24, the brake device 26, the steering device 58 (steering), and the like are controlled so that the automobile 20 travels along the target routes L1, L2 and parks in the target parking space 100.

[0025] In this case, the shift position SP is controlled by the shift ECU 50 based on an instruction from the surrounding recognition ECU 55. The engine ECU 23 controls the engine 22 based on a control signal from the electronic control unit 30 so that it is basically operated at an idling speed. The automatic transmission 24 is controlled by the ATECU 25 based on a control signal from the electronic control unit 30 so that the automatic transmission 24 is in the first forward gear when the shift position SP is a forward position, and in the reverse gear when the shift position SP is a reverse position. The brake device 26 is controlled by the brake ECU 27 based on a control signal from the electronic control unit 30 so that the driving force based on the rotation speed of the engine 22 is constant. The steering device 58 is controlled by the electronic control unit 30 based on information from the surrounding recognition ECU 94.

[0026] Next, the operation of the automobile 20 of the embodiment thus configured, particularly the operation during automatic parking, will be described. During automatic parking, as described above, the engine 22 is basically controlled to operate at the idling speed Nidl, and the driving for automatic parking is provided by the driving force (creep torque) due to the idling speed. In the idling control of the engine 22, the engine 22 is basically operated at the idling speed Nidl, but when the engine load changes due to turning on and off the air conditioner 74, the rotation speed Ne of the engine 22 increases or decreases, and the driving force (creep torque) also increases or decreases according to the increase or decrease in the rotation speed Ne of the engine 22, as calculated by the following formula (1). In formula (1), F is the driving force (creep torque), C is the capacity coefficient of the torque converter, T is the torque ratio of the torque converter, and G is a conversion coefficient taking into account the gear ratio, the differential ratio, and the tire diameter.

[0027] F=Ne 2 C T G (1)

[0028] In this embodiment, since an increase or decrease in driving force (creep torque) accompanying an increase or decrease in the rotation speed Ne of the engine 22 impedes the accuracy of stopping at the target parking position, the braking force is increased or decreased from the braking device 26 so that the driving force is constant with respect to an increase or decrease in the rotation speed Ne of the engine 22. Then, in order to obtain the rotation speed (calculation rotation speed) Nec for calculating the braking force to be output from the braking device 26, the electronic control unit 30 executes a calculation rotation speed setting process for automatic parking, as shown in FIG.

[0029] In the automatic parking calculation speed setting process, the electronic control unit 30 first executes a process of inputting data required to set the calculation speed Nec, such as the target speed Ne* of the engine 22, the speed Ne of the engine 22, and the previous read-ahead speed Nea (step S100). The target speed Ne* of the engine 22 is basically set to the idling speed Nidl, but when the engine load is changed, such as when the air conditioner 74 is turned on, a speed Nset greater than the idling speed Nidl is set as necessary, so that the speed thus set can be input. The speed Ne of the engine 22 can be inputted based on the crank angle θc from the crank position sensor by the engine ECU 23. The previous read-ahead speed Nea can be inputted based on the previous calculation performed by this automatic parking calculation speed setting process.

[0030] When the data is input in this manner, the rotation speed Ne of the engine 22 estimated after a predetermined period is calculated as the look-ahead rotation speed Nea (step S110). Here, as the predetermined period, a time required for the braking force calculated based on the calculation rotation speed Nec to be applied from the brake device 26 can be used, and a time obtained by an experiment or the like can be used. As a calculation method of the look-ahead rotation speed Nea, for example, the rotation speed Ne of the engine 22 can be changed by a rate value toward the target rotation speed Ne*, or the rotation speed Ne of the engine 22 can be smoothed toward the target rotation speed Ne*.

[0031] Next, it is determined whether the read-ahead rotation speed Nea is equal to or greater than the rotation speed Ne of the engine 22 (step S120). When it is determined that the read-ahead rotation speed Nea is equal to or greater than the rotation speed Ne of the engine 22, the read-ahead rotation speed Nea is set as the calculation rotation speed Nec and transmitted to the brake ECU 27 (step S130), and this process is terminated. The brake ECU 27 that has received the calculation rotation speed Nec calculates the driving force (creep torque) by substituting the calculation rotation speed Nec for "Ne" in the above-mentioned formula (1), and calculates the braking force to be output from the brake device 26 by subtracting the driving force to be output during automatic parking from this driving force F. Then, the brake device 26 is controlled so that the calculated braking force is output from the brake device 26. By setting the read-ahead rotation speed Nea as the calculation rotation speed Nec in this way, the driving force during automatic parking can be maintained approximately constant even if the rotation speed Ne of the engine 22 changes due to a change in the engine load.

[0032] On the other hand, when it is determined in step S120 that the read-ahead rotation speed Nea is less than the rotation speed Ne of the engine 22, the rotation speed Ne of the engine 22 is set as the calculation rotation speed Nec and transmitted to the brake ECU 27 (step S140), and this process ends. By setting the rotation speed Ne of the engine 22, which is greater than the read-ahead rotation speed Nea, as the calculation rotation speed Nec in this manner, it is possible to prevent the driving force during automatic parking from becoming excessively larger than the driving force at the idling rotation speed Nidl.

[0033] Now, consider a case where the target rotation speed Ne* is set to be large by turning on the air conditioner 74, etc., and the actual rotation speed Ne responds with a slight delay and coincides with the target rotation speed Ne* with a slight overshoot. FIG. 4 shows an example of the time change of the target rotation speed Ne*, the rotation speed Ne, and the read-ahead rotation speed Nea in this case. In the figure, the solid line A is the target rotation speed Ne*, the dashed line B is the actual rotation speed (the rotation speed of the engine 22) Ne, and the dashed line C is the read-ahead rotation speed Nea. When the target rotation speed Ne* becomes large at time T1, the actual rotation speed Ne changes with a slight delay from the target rotation speed Ne* and coincides with the target rotation speed Ne* with a slight overshoot. Since the read-ahead rotation speed Nea is the actual rotation speed Ne estimated after a predetermined period, it is calculated as a value larger than the actual rotation speed Ne from time T1 to time T2 during the overshoot of the actual rotation speed Ne*. Also, the read-ahead rotation speed Nea becomes smaller than the actual rotation speed Ne after time T2. Therefore, as the calculation rotation speed Nec, the read-ahead rotation speed Nea is used from time T1 to time T2, and the actual rotation speed Ne is used after time T2.

[0034] In the automobile 20 of the embodiment described above, during automatic parking, the engine 22 revolution speed Ne estimated after a predetermined period is calculated as the look-ahead revolution speed Nea, and when the look-ahead revolution speed Nea is equal to or greater than the actual revolution speed (the engine 22 revolution speed) Ne, the look-ahead revolution speed Nea is transmitted to the brake ECU 27 as the calculation revolution speed Nec. The brake ECU 27 calculates the driving force (creep torque) output from the engine 22 using the calculation revolution speed Nec, calculates the braking force to be output from the brake device 26 by subtracting the driving force to be output during automatic parking from this driving force F, and controls the brake device 26 so that the calculated braking force is output from the brake device 26. This makes it possible to keep the driving force during automatic parking approximately constant even if the engine 22 revolution speed Ne changes due to a change in engine load. When the look-ahead revolution speed Nea is less than the actual revolution speed (the engine 22 revolution speed) Ne, the actual revolution speed Ne is transmitted to the brake ECU 27 as the calculation revolution speed Nec. This makes it possible to prevent the driving force during automatic parking from becoming excessively larger than the driving force at the idling speed Nidl. As a result, it is possible to more reliably stop the vehicle at the target position.

[0035] In the automobile 20 of the embodiment, the engine ECU 23 is used to control the engine 22, the ATECU 24 is used to control the automatic transmission 24, and the brake ECU 27 is used to control the braking device 26, but all or part of the functions of the engine ECU 23, the ATECU 24, and the brake ECU 27 may be performed by the electronic control unit 30. When the function of the brake ECU 27 is performed by the electronic control unit 30, steps S130 and S140 may be used to set the calculation rotation speed Nec.

[0036] The relationship between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be described below. In the embodiment, the engine 22 corresponds to the "engine", and the electronic control unit 30, the engine ECU 23, the TECU 25, the brake ECU 27, etc. correspond to the "control device".

[0037] The correspondence between the main elements of the Examples and the main elements of the invention described in the Summary of the Problem column does not limit the elements of the invention described in the Summary of the Problem column, since the Examples are examples for specifically explaining the mode for implementing the invention described in the Summary of the Problem column. In other words, the interpretation of the invention described in the Summary of the Problem column should be based on the description in that column, and the Examples are merely a specific example of the invention described in the Summary of the Problem column.

[0038] Although the form for carrying out the present invention has been described above using examples, the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms without departing from the scope of the gist of the present invention. [Industrial Applicability]

[0039] The present invention can be used in the automobile manufacturing industry and the like. [Explanation of symbols]

[0040] 20 automobile, 22 engine, 23 engine electronic control unit (engine ECU), 24 automatic transmission, 25 automatic transmission electronic control unit (ATECU), 26 brake device, 27 brake device electronic control unit (brake ECU), 28, steering device, 29 differential gear, 29a, 29b drive wheel, 30 electronic control unit, 31 CPU, 32 ROM, 33 RAM, 34 flash memory, 40 ignition switch, 41 vehicle speed sensor, 42 wheel speed sensor, 43 acceleration sensor, 44 yaw rate sensor, 45 gradient sensor, 46 accelerator pedal, 47 accelerator pedal position sensor, 48 brake pedal, 49 brake pedal position sensor, 50 shift electronic control unit (shift ECU), 51 shift lever, 52 shift position sensor, 55 surrounding recognition electronic control unit (surrounding recognition ECU), 56 surrounding recognition device, 57 Automatic driving switch, 58 automatic parking switch, 60 navigation device, 62 main body, 64 GPS antenna, 66 display, 70 display device, 72 communication device, 74 air conditioning device, 100 target parking space, L1, L2 routes.

Claims

[Claim 1] An automobile including an engine and a control device that performs brake control on a driving force based on a rotation speed of the engine when performing automatic parking using power from the engine, the control device executes a process of setting a calculation rotation speed during automatic parking, which calculates a rotation speed estimated after a predetermined period of time of the engine as a look-ahead rotation speed, and when the look-ahead rotation speed is equal to or greater than an actual rotation speed of the engine, sets the look-ahead rotation speed as a calculation rotation speed for calculating the driving force, and when the look-ahead rotation speed is less than the actual rotation speed, sets the actual rotation speed as the calculation rotation speed; The predetermined period is a time required for the braking force calculated based on the calculation rotation speed obtained by the automatic parking calculation rotation speed setting process to act. A vehicle characterized by:

Images