Driving assistance devices

Abstract

To provide a driving support device capable of reducing a sense of discomfort upon switching between control by a user's operation and ACC control.SOLUTION: A driving support device includes: first control means which performs control to accelerate and decelerate an own vehicle mounted with a drive motor for generating power for traveling, with first request torque requested for maintaining an inter-vehicle distance between the own vehicle and a preceding vehicle ahead thereof at a target value, and to allow the own vehicle to travel while following the preceding vehicle; second control means which performs control to accelerate and decelerate the own vehicle with second request torque requested in response to operation performed by a user of the own vehicle; and restriction means which restricts the variation per unit time of torque for driving a wheel when the first request torque is greater than the second request torque upon the start of the control by the first control means.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a driving assistance device. [Background technology]

[0002] Recent vehicles are being equipped with a function that allows the host vehicle to travel by following the vehicle ahead, known as adaptive cruise control (ACC). During control using the ACC function (ACC control), a target inter-vehicle distance between the host vehicle and the preceding vehicle is set based on the host vehicle's speed, and the target inter-vehicle distance is subtracted from the actual inter-vehicle distance to determine the inter-vehicle distance deviation (= inter-vehicle distance - target inter-vehicle distance). The relative speed between the host vehicle and the preceding vehicle is also determined. A target acceleration / deceleration rate is then set according to the inter-vehicle distance deviation and the relative speed, and the drive torque of the host vehicle is controlled so that the host vehicle accelerates or decelerates at the target acceleration / deceleration rate.

[0003] Furthermore, for example, a series hybrid system includes an engine, a generator motor that generates electricity using engine power, a drive motor that generates driving force for traveling, and a battery that stores the power supplied to the drive motor. In a vehicle equipped with such a hybrid system, when the output required of the drive motor is smaller than the output of the battery, the drive motor is driven by power from the battery, and the driving force is transmitted from the drive motor to the drive wheels. On the other hand, when the output required of the drive motor exceeds the output of the battery, the engine power is converted into electric power by the generator motor, and the drive motor is driven by the electric power from the generator motor, and the driving force is transmitted from the drive motor to the drive wheels. Furthermore, when the vehicle decelerates, the drive motor operates in regenerative mode, and the power transmitted from the drive wheels to the drive motor is converted into electric power. At this time, the drive motor acts as a resistance to the traveling drive system, and this resistance acts as a torque (regenerative torque) that brakes the vehicle. The electric power generated by the drive motor is stored in a battery and used to drive the drive motor (see, for example, Patent Document 1).

[0004] The above-described systems set a target value (required torque) when controlling the drive torque. The required torque can be either the ACC required torque calculated and set by the ACC control or the user required torque set in response to the pedal operation by the user. Some such systems adopt the larger of the ACC required torque and the user required torque during ACC control. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-098307 Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-described system, for example, if a selector switch is operated during control by a user operating the pedal to start ACC control, the required torque used as the target value switches from the user-requested torque to the ACC-requested torque. This can cause a sudden change in the user's perception of acceleration or deceleration, potentially causing discomfort or anxiety. This phenomenon tends to be more pronounced in series hybrid systems, which tend to have a strong regenerative torque. More specifically, for example, if ACC control is initiated while the vehicle is approaching a preceding vehicle during coasting deceleration during normal driving, braking control is performed immediately after the ACC control starts. At this time, the required torque switches from the user-requested torque to the ACC-requested torque, causing a sudden increase in drive torque. In this case, the user may feel as if the deceleration G has disappeared, even though they want to decelerate.

[0007] The present invention has been made in view of the above, and has an object to provide a driving assistance device that can reduce the sense of discomfort felt when switching between control based on user operation and ACC control. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, a driving assistance device according to the present invention includes a first control means for controlling a host vehicle, which is a vehicle equipped with a drive motor that generates power for driving, to accelerate and decelerate the host vehicle with a first required torque required to maintain a target inter-vehicle distance between the host vehicle and a preceding vehicle ahead of the host vehicle, and a second control means for controlling the host vehicle to accelerate and decelerate with a second required torque required in accordance with an operation performed by a user of the host vehicle, and when the first required torque is greater than the second required torque at the start of control by the first control means, When switching from the second required torque by the second control means to the first required torque by the first control means and limiting means for limiting the amount of change in torque per unit time. When the first control means starts control, if the first required torque is smaller than the second required torque, the limiting means does not perform the limiting operation. .

[0009] According to this configuration, when the torque driving the wheels is changed to be larger, the amount of change per unit time is limited, thereby reducing the sense of discomfort when switching between control by the second control means and control by the first control means, and preventing inconveniences such as feeling like the deceleration G has suddenly disappeared or that the vehicle is suddenly accelerating. Furthermore, with this configuration, the user's intention indicated via the second required torque and the second control means can be reflected, thereby increasing the user's satisfaction.

[0010] Further, the driving assistance device according to the present invention comprises: a first control means for controlling a host vehicle, which is a vehicle equipped with a drive motor that generates power for driving, to accelerate and decelerate the host vehicle with a first required torque that is required to maintain a target inter-vehicle distance between the host vehicle and a preceding vehicle ahead of the host vehicle; a second control means for controlling the host vehicle to accelerate and decelerate with a second required torque that is required in accordance with an operation performed by a user of the host vehicle; and a limiting means for limiting a torque change per unit time when switching from the second required torque by the second control means to the first required torque by the first control means, if the first required torque is greater than the second required torque at the start of control by the first control means, wherein the second control means applies a regenerative braking force by the drive motor during deceleration, and a deceleration rate due to the regenerative braking force of the second control means is stronger than a deceleration rate due to the first control means, and the limiting means is configured to limit a change in torque per unit time when the first required torque is greater than the second required torque at the start of control by the first control means, during inertial deceleration when the preceding vehicle is present and the regenerative braking force of the second control means is being applied, Do the following.

[0011] According to this configuration, Since the amount of change per unit time is limited when the torque for driving the wheels is changed to increase, it is possible to reduce the sense of discomfort felt when switching between control by the second control means and control by the first control means, and to prevent inconveniences such as feeling that the deceleration G has suddenly disappeared or that the vehicle has suddenly accelerated. Also, with this configuration, it is possible to reflect the second required torque and the user's intentions expressed via the second control means, thereby increasing user satisfaction. It is possible.

[0012] Further, the driving assistance device according to the present invention comprises: The limiting means does not perform the limiting operation if the first required torque is smaller than the second required torque at the start of control by the first control means. .

[0013] According to this configuration, The second required torque and the user's intention indicated through the second control means can be reflected, thereby increasing the user's satisfaction. It is possible.

[0014] Further, the driving assistance device according to the present invention comprises: During the control of the first control means, the larger of the first required torque by the first control means and the second required torque by the second control means is adopted, and when the second required torque is larger than the first required torque, the limiting means does not perform the limiting. .

[0015] According to this configuration, For example, when a user wants to accelerate quickly, the first control means can avoid the inconvenience of limiting the amount of change in torque per unit time, thereby increasing user satisfaction. It is possible. [Effects of the Invention]

[0016] The driving assistance device according to the present invention has an effect of reducing the sense of discomfort felt when switching between control based on user operation and ACC control. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram showing the configuration of a hybrid vehicle according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of a functional configuration of a control unit according to the embodiment. [Figure 3] FIG. 3 is a graph showing an example of torque transition according to the embodiment. [Figure 4] FIG. 4 is a graph showing an example of torque transition according to the embodiment. [Figure 5] FIG. 5 is a flowchart illustrating an example of a flow of processing executed by the control unit according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] An example of a driving assistance device according to the present invention will be described in detail below with reference to the drawings.

[0019] 1 is a block diagram showing the configuration of a hybrid vehicle 1 according to a first embodiment. The hybrid vehicle 1 is an example of a vehicle, and includes a drive motor that acts as a resistance in a driving drive system. The hybrid vehicle 1 is also equipped with a series hybrid system 2. The hybrid system 2 includes an engine 11, a generator motor 12, a drive motor 13, a battery 14, and a PCU (Power Control Unit) 15.

[0020] The engine 11 is, for example, a gasoline engine, and is equipped with a throttle body, a fuel injector that injects fuel into intake air, etc. The throttle body is a component that takes in fuel and air and sends them to the combustion chamber of the engine 11, and is equipped with an electronic throttle valve that adjusts the amount of intake air into the combustion chamber of the engine 11, a throttle position sensor that detects the opening of the electronic throttle valve, and a control valve that adjusts the amount of intake air when idling, such as when the vehicle is stopped. The engine 11 is also equipped with a starter for starting it.

[0021] The generator motor 12 generates electricity using the power of the engine 11 and is, for example, a permanent magnet synchronous motor. The rotating shaft of the generator motor 12 is mechanically connected to the crankshaft of the engine 11 via a gear (not shown). For example, an engine output gear is supported on the crankshaft of the engine 11 so as not to rotate relative to it, and a motor gear is supported on the rotating shaft of the generator motor 12 so as not to rotate relative to it, and the engine output gear and the motor gear are in mesh with each other.

[0022] The drive motor 13 generates power for driving the vehicle and is, for example, a permanent magnet synchronous motor that is larger than the generator motor 12. The rotating shaft of the drive motor 13 is connected to a drive system 16 of the hybrid vehicle 1. The drive system 16 includes a differential gear, and the power of the drive motor 13 is transmitted to the differential gear, and then distributed and transmitted from the differential gear to drive wheels 17 consisting of left and right front or rear wheels. This causes the left and right drive wheels 17 to rotate, causing the hybrid vehicle 1 to move forward or backward.

[0023] The battery 14 is an assembled battery made up of a plurality of secondary batteries, and stores power. The secondary batteries are, for example, lithium-ion batteries. The battery 14 outputs DC power of, for example, about 200 to 350 V (volts).

[0024] The PCU 15 is a unit for controlling the driving of the generator motor 12 and the drive motor 13, and includes a first inverter 21, a second inverter 22, and a converter .

[0025] When starting the engine 11, the DC power output from the battery 14 is boosted by the converter 23, the boosted DC power is converted into AC power by the first inverter 21, and the AC power is supplied to the generator motor 12. This causes the generator motor 12 to perform power running, and the engine 11 is motored (cranked) by the generator motor 12. When the rotation speed of the crankshaft of the engine 11 has increased to the rotation speed required for starting due to motoring, the ignition plug of the engine 11 is sparked, and the engine 11 starts.

[0026] When the hybrid vehicle 1 is traveling, the drive motor 13 is operated in a power running mode, and the drive motor 13 generates power.

[0027] When the output required of the drive motor 13 is smaller than the output of the battery 14, the hybrid vehicle 1 runs in EV mode. That is, the engine 11 is stopped, the generator motor 12 does not generate electricity, and power is supplied from the battery 14 to the drive motor 13, which is then driven by the power.

[0028] On the other hand, when the output required of the drive motor 13 exceeds the output of the battery 14, the hybrid vehicle 1 runs in HV mode. That is, the engine 11 is put into operation and the generator motor 12 is operated to generate electricity (regenerative operation), so that the power of the engine 11 is converted into AC power by the generator motor 12. The AC power from the generator motor 12 is then converted into DC power by the first inverter 21, and the DC power output from the first inverter 21 is converted into AC power by the second inverter 22. The AC power is supplied to the drive motor 13, thereby driving the drive motor 13.

[0029] Furthermore, when the remaining capacity of the battery 14 falls below a predetermined level, the generator motor 12 operates to generate electricity while the engine 11 is running, regardless of whether the drive motor 13 is running or stopped. At this time, AC power from the generator motor 12 is converted to DC power by the first inverter 21, and the DC power output from the first inverter 21 is stepped down by the converter 23. The stepped-down DC power is supplied to the battery 14, thereby charging the battery 14.

[0030] When the hybrid vehicle 1 decelerates, the drive motor 13 undergoes regenerative operation, and power transmitted from the drive wheels 17 to the drive motor 13 is converted into AC power. At this time, the drive motor 13 acts as a resistor in the traveling drive system, and this resistance acts as a braking force (regenerative braking force) that brakes the hybrid vehicle 1. At this time, in the PCU 15, the AC power supplied from the drive motor 13 to the second inverter 22 is converted into DC power by the second inverter 22, and the DC power output from the second inverter 22 is stepped down by the converter 23. The stepped-down DC power is then supplied to the battery 14, thereby charging the battery 14.

[0031] The hybrid vehicle 1 is equipped with a plurality of ECUs (Electronic Control Units). Each ECU has a microcontroller unit (microcomputer), which incorporates, for example, a CPU, a nonvolatile memory such as a flash memory, and a volatile memory such as a dynamic random access memory (DRAM). The plurality of ECUs are connected to enable bidirectional communication using the CAN (Controller Area Network) communication protocol. Each ECU is connected to various sensors required for control, and receives detection signals from the connected sensors. In addition to the detection signals received from the various sensors, each ECU also receives information required for control from other ECUs.

[0032] 1 shows an ECU 31, one of the multiple ECUs, that controls the hybrid system 2. The ECU 31 is an example of a driving assistance device. An accelerator sensor 32, a vehicle speed sensor 33, a forward recognition camera 34 (external environment recognition means that recognizes the external environment around the vehicle), and an ACC selector switch 35 are connected to the ECU 31.

[0033] Accelerator sensor 32 outputs a detection signal corresponding to the amount of operation of the accelerator pedal operated by the driver (operator). Vehicle speed sensor 33 outputs a detection signal, a pulse signal synchronized with the rotation of a rotor that rotates as hybrid vehicle 1 travels. ECU 31 determines the accelerator opening, which is the ratio of the current operation amount to the maximum operation amount of the accelerator pedal, from the detection signal of accelerator sensor 32. ECU 31 also determines the frequency of the detection signal (pulse signal) from the detection signal of vehicle speed sensor 33 and converts the frequency into vehicle speed.

[0034] The forward recognition camera 34 is, for example, a stereo camera. The stereo camera is a camera that can continuously capture still images at a predetermined frame rate and can detect the distance to the position of a target in the captured image from parallax information. The stereo camera is installed, for example, on the windshield surface behind the rearview mirror in the front center of the passenger compartment so that it can capture images of the area ahead of the hybrid vehicle 1 at a wide angle. In addition to the stereo camera, the hybrid vehicle 1 may also be provided with a radar as a unit that recognizes the outside world. The radar is installed in the front of the hybrid vehicle 1 and is a sensor that detects the situation within a predetermined search range ahead of the hybrid vehicle 1. The radar irradiates radar waves (millimeter waves, laser) into the search range, receives reflected waves from objects present within the search range, and outputs a detection signal corresponding to the reflected waves.

[0035] The output of the forward recognition camera 34 is output to the ECU 31. The ECU 31 realizes functional units (a vehicle distance calculation unit 301, a relative vehicle speed calculation unit 302, and a target acceleration calculation unit 305, which will be described later) that calculate data necessary to operate the ACC function, such as the relative speed between a target such as a preceding vehicle and the hybrid vehicle 1, a target inter-vehicle distance from the preceding vehicle, and a target acceleration / deceleration speed when following the preceding vehicle, based on the image captured by the forward recognition camera 34.

[0036] Furthermore, when the distance between the preceding vehicle and the hybrid vehicle 1 becomes wider than the target distance and acceleration (or becomes narrower and deceleration is required) becomes necessary, the ECU 31 transmits a control signal to the engine 11. When the engine 11 receives the control signal, it transmits a throttle control signal to the throttle body to control the throttle opening, and also transmits a fuel injection control signal to the fuel injector to control the amount of fuel injected, in order to realize acceleration based on the signal.

[0037] Normally (when the ACC function is not activated), the ECU 31 controls the throttle opening and closing of the engine so that a driving torque corresponding to the accelerator operation amount (accelerator opening amount) detected by an accelerator sensor (not shown) is output, and also controls the amount of fuel injected by the fuel injector. On the other hand, when the ACC function is activated, as described above, the ECU 31 controls the throttle opening and the amount of fuel injected based on a control signal so that acceleration corresponding to the signal is achieved, regardless of the accelerator operation amount.

[0038] The ACC function is a follow-up cruise control that causes the hybrid vehicle 1 to follow a preceding vehicle that is ahead of it. For example, the steering wheel is provided with an ACC selector switch 35 that accepts an operation to switch control by the ACC function on / off. When the ACC selector switch 35 is operated, the ECU 31 starts or ends control by the ACC function. In ACC control (follow-up cruise control), which causes the hybrid vehicle 1 to follow a preceding vehicle ahead of it, the hybrid vehicle 1 automatically switches between following the preceding vehicle and constant speed cruise at a predetermined vehicle speed depending on whether or not there is a preceding vehicle. During follow-up cruise, the hybrid vehicle 1 is accelerated or decelerated so that the distance between the hybrid vehicle 1 and the preceding vehicle ahead of it is maintained at a target distance.

[0039] Specifically, a target inter-vehicle distance between hybrid vehicle 1 and a preceding vehicle is set based on the vehicle speed of hybrid vehicle 1, and ECU 31 determines the inter-vehicle distance deviation between the target inter-vehicle distance and the actual inter-vehicle distance (= actual inter-vehicle distance - target inter-vehicle distance). ECU 31 also determines the relative speed between hybrid vehicle 1 and the preceding vehicle. ECU 31 then sets a target acceleration / deceleration speed for hybrid vehicle 1 according to the inter-vehicle distance deviation and the relative speed. A non-volatile memory built into the microcomputer of ECU 31 stores the characteristics (relationships) of the target acceleration / deceleration speed with respect to the inter-vehicle distance deviation and the relative speed in the form of a map as a target acceleration / deceleration speed map. Once the target acceleration / deceleration speed is set, the engine output is controlled so that hybrid vehicle 1 accelerates or decelerates at the target acceleration / deceleration speed (automatic acceleration / deceleration).

[0040] 2 is a diagram showing an example of the functional configuration of the control unit 300 according to this embodiment. The ECU 31 realizes the control unit 300 by causing the CPU to execute various programs stored in the memory. The control unit 300 functions as a vehicle distance calculation unit 301, a relative vehicle speed calculation unit 302, a user requested torque calculation unit 303, an ACC control unit 304, a target acceleration calculation unit 305, a request non-achievement determination unit 306, a restriction release determination unit 307, a change amount restriction unit 308, etc.

[0041] In the hybrid system 2 according to this embodiment, the CPU executes various programs stored in the memory to realize the various functional units described above, but this is not limited to this, and each functional unit can also be realized by hardware.

[0042] The vehicle distance calculation unit 301 calculates a target vehicle distance from the preceding vehicle based on the output of the forward recognition camera 34. The relative vehicle speed calculation unit 302 calculates the relative speed between the hybrid vehicle 1 and a target such as a preceding vehicle based on the output of the forward recognition camera 34.

[0043] The user requested torque calculation unit 303 calculates a requested torque to be used to drive the wheels, in accordance with the accelerator opening (described above) obtained based on the output of the accelerator sensor 32. The requested torque is a target value for the driving torque. Using the output of the user requested torque calculation unit 303, the control unit 300 performs control to accelerate or decelerate the hybrid vehicle 1 with a user requested torque (second requested torque) requested in accordance with a user operation (an example of a second control means).

[0044] The ACC control unit 304 is an example of a first control means, and performs control to accelerate or decelerate the host vehicle using an ACC required torque (first required torque) required to maintain a target inter-vehicle distance between the host vehicle and a preceding vehicle ahead of it, thereby causing the host vehicle to travel while following the preceding vehicle. When ACC control is turned on by the ACC selector switch 35, the ACC control unit 304 performs ACC control using the outputs of the vehicle distance calculation unit 301, the relative vehicle speed calculation unit 302, and the user required torque calculation unit 303. Furthermore, when the ACC control is turned off due to a predetermined user behavior, the ACC control unit 304 terminates the ACC control. Here, the predetermined user behavior is, for example, an operation to switch off the ACC control using the ACC selector switch 35 or an operation to depress the brake pedal.

[0045] During ACC control, target acceleration calculation unit 305 calculates the target acceleration / deceleration when following a preceding vehicle, based on the output of forward recognition camera 34. Using the target acceleration / deceleration output by target acceleration calculation unit 305, ACC control unit 304 calculates ACC required torque, which is the target value of drive torque during ACC control.

[0046] When control is switched from control based on the user's accelerator pedal operation to ACC control, if the ACC required torque is greater than the user required torque, control unit 300 limits the amount of change in the required torque per unit time. Request unachievement determination unit 306, restriction release determination unit 307, and change amount limiting unit 308 are used to limit the amount of change described above.

[0047] That is, the request unachievement determination unit 306 determines whether the request torque, which has been smaller than the ACC request torque since the current ACC control was started, has not reached (has never reached) the ACC request torque. The change amount limiting unit 308 is an example of a limiting means that limits the amount of change described above, and when there is a difference between the ACC required torque and the previous value of the required torque (previous required torque) that is equal to or greater than a predetermined value, it performs control to change the required torque by the predetermined value. Furthermore, the restriction release determination unit 307 determines whether the required torque has reached a predetermined threshold value. This threshold value is set so that when the required torque reaches the threshold value, the restriction on the torque change amount that has been imposed up to that point is released (ended).

[0048] Fig. 3 is a graph showing an example of torque transitions according to this embodiment. In this figure, the vertical axis of the graph represents torque value (unit: Nm (Newton meters)) and the horizontal axis represents time (unit: s (seconds)). This figure also shows the transitions of three types of torque: user requested torque, ACC requested torque, and requested torque. This figure also shows the on / off timing of ACC control and brake control by the ACC function.

[0049] This example shows a case where ACC control is initiated while the vehicle is approaching a preceding vehicle during coasting deceleration during normal driving (i.e., during acceleration / deceleration control by the user's pedal operation with the accelerator pedal released). In this case, brake control is performed immediately after ACC control starts (i.e., as ACC control starts). In this example, the user requested torque is constant at -50 (Nm), and the ACC requested torque is constant at -30 (Nm).

[0050] 3, during control by the user operating the accelerator pedal (i.e., when ACC control is not in progress), the ACC selector switch 35 is operated at timing 0.9 (s) on the graph, and ACC control is started at timing 1 (s) on the graph. As a result, ACC brake control also switches from off to on between timings 0.9 (s) and 1 (s) on the graph.

[0051] In this case, with a conventional system, the required torque (shown by the thick line), which is the target value of the drive torque, is instantaneously switched as shown by the two-dot chain arrow C, and the drive torque, which is changed according to the required torque, also increases sharply (rising). In this case, the user feels as if the deceleration G has been lost even though they want to decelerate, which causes discomfort and anxiety for the user.

[0052] In contrast, in this embodiment, when switching the required torque, the amount of change per unit time is limited. Specifically, a value (for example, 187.5 (Nm / s) or less) that is unlikely to cause discomfort to the user is adopted as the amount of change per unit time, and the required torque is switched by repeatedly changing this value. By controlling in this way, the required torque (and drive torque) would previously have risen by as much as 30 (Nm) instantaneously, but in the example of FIG. 3, it is gradually increased over approximately 2 (s). This makes it less likely that the user will feel uncomfortable or uneasy.

[0053] Fig. 4 is a graph showing an example of torque transitions according to this embodiment. In this figure, the vertical axis of the graph represents torque value (unit: Nm) and the horizontal axis represents time (unit: s (seconds)). This figure also shows the transitions of three types of torque: user requested torque, ACC requested torque, and requested torque. This figure also shows the on / off timing of ACC control and brake control by the ACC function.

[0054] This example shows a case where ACC control is initiated while the vehicle is approaching a preceding vehicle during normal driving by coasting deceleration (i.e., during acceleration / deceleration control by the user's pedal operation with the accelerator pedal released). In this example, the user requested torque is constant at -50 (Nm), and the ACC requested torque is constant at -30 (Nm).

[0055] This example differs from the example in Figure 3 in that the ACC requested torque increases from timing 1 (s) due to the relationship between the relative speed and distance to the preceding vehicle. Note that there is no change in the user requested torque during this time, i.e., the user does not operate the accelerator pedal.

[0056] In this example, the ACC required torque changes from a negative value to a positive value at a timing of about 1.5 (s). In other words, the hybrid vehicle 1 in this example changes from a deceleration state to an acceleration state due to the ACC control.

[0057] In the example shown in FIG. 4, during control by the user operating the accelerator pedal (i.e., when ACC control is not in progress), the ACC changeover switch 35 is operated at timing 0.9 (s) on the graph, and ACC control is started at timing 1 (s) on the graph.

[0058] In this example, in the case of a conventional system, as explained above, the required torque (shown by the thick line), which is the target value of the driving torque, is instantaneously switched from the user required torque to the ACC required torque, and as a result, the driving torque also rises sharply. However, in this embodiment, in this example as well, the amount of change per unit time is limited when switching the required torque, as in the example of Fig. 3. Specifically, a value that is unlikely to cause discomfort to the user (for example, 187.5 (Nm / s) or less) is adopted as the amount of change per unit time, and the required torque is switched by repeatedly changing this value.

[0059] In this example, the ACC required torque gradually increases from time 1 (s). For this reason, while the required torque reaches the ACC required torque around time 2 (s) in the example in Figure 3, this does not happen in the example in Figure 4, and it takes time to switch the required torque by the amount of the increase in the ACC required torque.

[0060] Furthermore, the ACC required torque changes from a negative value to a positive value at a timing (indicated by symbol D) after about 1.5 (s). That is, the hybrid vehicle 1 in this example changes from a deceleration state to an acceleration state due to ACC control. The required torque, which changes in accordance with the ACC required torque, also changes from deceleration to acceleration at a timing (indicated by symbol E) after about 2.5 (s). In this embodiment, at this timing, that is, at the timing when the required torque becomes 0 (Nm), the control unit 300 performs control to immediately fill the difference between the ACC required torque and the required torque.

[0061] In this embodiment, as described above, the control is performed to match the required torque with the ACC required torque when the threshold value reaches 0 (Nm), but a predetermined value other than 0 (Nm) may be set as the threshold value for performing this control.

[0062] Furthermore, the example shown in Fig. 4 illustrates the start of ACC control during coasting deceleration, but the limit on the amount of change in the required torque per unit time described in Fig. 4 may also be applied during times other than coasting deceleration. For example, the limit on the amount of change shown in Fig. 4 may also be applied when the user presses the ACC selector switch 35 while depressing the accelerator pedal.

[0063] 5 is a flowchart showing an example of the flow of processing executed by the control unit 300 according to this embodiment. This processing realizes the ACC control shown in FIGS.

[0064] 3 and 4 show adjacent dots spaced at intervals of approximately 0.1 seconds, the present embodiment will be described assuming that the control unit 300 loops through this flowchart every approximately 0.1 seconds. However, in practice, the control unit 300 may loop the process at intervals different from those in the present embodiment, for example, at intervals of approximately 8 milliseconds.

[0065] The control unit 300 first determines whether ACC control is in progress (step S1). If ACC control is in progress in step S1 (Yes in step S1), the control unit 300 compares the ACC request torque with the user request torque (step S2).

[0066] If the ACC required torque exceeds the user required torque in step S2 (Yes in step S2), the control unit 300 determines whether the required torque, which was smaller than the ACC required torque after the current ACC control started, has not reached the ACC required torque (step S3).

[0067] If it is determined in step S3 that the required torque has not reached the ACC required torque (Yes in step S3), the control unit 300 determines whether the previous value of the required torque (previous required torque) is less than a predetermined threshold value A (step S4). Here, the threshold value A is, for example, 0 (Nm).

[0068] If the previous required torque is less than threshold value A in step S4 (Yes in step S4), control unit 300 determines whether the difference between the ACC required torque and the previous required torque is greater than a predetermined value (constant B) (step S5).

[0069] If the difference between the ACC required torque and the previous required torque is greater than constant B in step S5 (Yes in step S5), the control unit 300 performs control to change the required torque to a value obtained by adding constant B to the previous required torque (step S6). By this process, the amount of change in the required torque is limited to constant B. After step S6, the control unit 300 returns the process to step S1.

[0070] If it is determined in step S3 that the required torque has reached the ACC required torque (No in step S3), the control unit 300 proceeds to step S7, matches the required torque to the ACC required torque, and then returns the process to step S1. As a result, the required torque is maintained in a state that matches the ACC required torque while the current ACC control is being executed.

[0071] Furthermore, if it is determined in step S4 that the previous required torque is equal to or greater than threshold value A (No in step S4), control unit 300 proceeds to step S7, matches the required torque to the ACC required torque, and then returns the process to step S1. As a result, if the required torque for the current ACC control gradually increases and becomes equal to or greater than threshold value A, the restriction on the amount of change in the required torque is released, and the difference between the required torque and the ACC required torque is immediately eliminated.

[0072] If ACC control is not in progress in step S1 (No in step S1), or if the ACC required torque is equal to or less than the user required torque in step S2 (No in step S2), the control unit 300 proceeds to step S8. In step S8, the control unit 300 adopts the user required torque determined by the pedal operation of the user as the required torque, matches the required torque to the user required torque, and returns the process to step S1.

[0073] The above-described processing can implement the control exemplified in Figures 3 and 4. That is, according to this embodiment, in a situation where a sudden change in the required torque is likely, the amount of change is limited, thereby reducing the sense of discomfort felt when switching between control based on user operation and ACC control.

[0074] Furthermore, according to this embodiment, the restriction on the amount of change in the required torque can be released (ended) when a predetermined condition is met.

[0075] In the above embodiment, the amount of change per unit time is a fixed value (constant B), but in practice, the amount of change per unit time may not be a constant but may be determined by calculation. For example, the amount of change per unit time may be calculated by fixing the time required for the change. Specifically, if it is desired to complete the change in the required torque in 2 (s), the amount of change per unit time can be calculated using the following formula: Amount of change per unit time = (ACC required torque - current required torque) / (2 (s) / unit time (s))

[0076] It is also preferable to increase the rate of change in the required torque per unit time as the vehicle speed increases, and as the difference between the ACC required torque and the current required torque increases.

[0077] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

[0078] For example, the present invention is not limited to series hybrid vehicles, but may also be applied to parallel hybrid vehicles, electric vehicles, and fuel cell vehicles.

[0079] In the above embodiment, a hybrid vehicle equipped with an engine, a generator motor that generates electricity using engine power, and a battery that stores the electricity has been described as an example, but the present invention is not limited to this. For example, the present invention may be applied to an electric vehicle or a fuel cell vehicle without an engine that includes a drive motor that acts as a resistance in the driving system.

[0080] In the above embodiment, when the requested torque reaches a predetermined threshold during the limiting of the change amount of the requested torque, the limiting of the change amount of the requested torque that had been in effect up until that point is released (terminated). However, this is not a limitation. For example, the limiting of the change amount of the requested torque may be weakened rather than terminated. In other words, the change amount per unit time may be changed to a larger value after the threshold is reached than before the threshold is reached. [Explanation of symbols]

[0081] 1... Hybrid vehicle (an example of a vehicle), 2... Hybrid system, 11...engine, 12...generator motor, 13...drive motor, 14...battery, 15...PCU, 16...drive system, 17...drive wheels, 21...first inverter, 22...second inverter, 23...converter, 31...ECU, 32...accelerator sensor, 33...vehicle speed sensor, 34...Forward recognition camera, 35...ACC switch, 300...control unit, 301... vehicle distance calculation unit, 302... relative vehicle speed calculation unit, 303... user required torque calculation unit 304...ACC control unit, 305...target acceleration calculation unit, 306: request unachievement determining unit; 307: restriction release determining unit; 308: change amount restricting unit.

Claims

1. a first control means for controlling the host vehicle, which is a vehicle equipped with a drive motor that generates power for traveling, to accelerate or decelerate the host vehicle with a first required torque required to maintain a target inter-vehicle distance between the host vehicle and a preceding vehicle, and for causing the host vehicle to travel in a manner that follows the preceding vehicle; a second control means for performing control to accelerate or decelerate the host vehicle with a second required torque that is required in response to an operation performed by a user of the host vehicle; a limiting means for limiting a change amount of torque per unit time when switching from the second required torque by the second control means to the first required torque by the first control means when the first required torque is greater than the second required torque at the start of control by the first control means; and Equipped with The limiting means does not perform the limiting operation if the first required torque is smaller than the second required torque at the start of control by the first control means. Driving assistance device.

2. a first control means for controlling the host vehicle, which is a vehicle equipped with a drive motor that generates power for traveling, to accelerate or decelerate the host vehicle with a first required torque required to maintain a target inter-vehicle distance between the host vehicle and a preceding vehicle, and for causing the host vehicle to travel in a manner that follows the preceding vehicle; a second control means for performing control to accelerate or decelerate the host vehicle with a second required torque that is required in response to an operation performed by a user of the host vehicle; a limiting means for limiting a change amount of torque per unit time when switching from the second required torque by the second control means to the first required torque by the first control means when the first required torque is greater than the second required torque at the start of control by the first control means; and Equipped with the second control means applies a regenerative braking force by the drive motor during deceleration, the deceleration caused by the regenerative braking force of the second control means is stronger than the deceleration caused by the first control means, The limiting means performs the limiting operation when the first required torque is greater than the second required torque at the start of control by the first control means during inertial deceleration in which the preceding vehicle is present and the regenerative braking force of the second control means is acting. Driving assistance device.

3. The limiting means does not perform the limiting when the first required torque is smaller than the second required torque at the start of control by the first control means. The driving assistance device according to claim 2 .

4. During control by the first control means, the larger of the first required torque by the first control means and the second required torque by the second control means is adopted, and when the second required torque is larger than the first required torque, the limiting means does not perform the limiting. The driving assistance device according to claim 1 or 2.

5. When the torque reaches a predetermined threshold value during the limiting of the amount of change in torque when switching from the second required torque by the second control means to the first required torque by the first control means, the limiting means suppresses the limiting of the amount of change and makes a change such that the torque when switching from the second required torque by the second control means to the first required torque by the first control means is increased to the first required torque. The driving assistance device according to any one of claims 1 to 3.

6. The limiting means limits the amount of change in torque when switching from the second required torque by the second control means to the first required torque by the first control means, when control to decelerate the host vehicle is activated in response to the start of control by the first control means. The driving assistance device according to any one of claims 1 to 4.

7. The limiting means suppresses the limit on the amount of change in torque when switching from the second required torque by the second control means to the first required torque by the first control means, when the control by the first control means switches from control to control to accelerate the host vehicle. The driving assistance device according to any one of claims 1 to 5.

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