Vehicle speed limiting device

Abstract

To provide a vehicle speed limiting device capable of preventing the vehicle speed from exceeding an upper limit speed due to an inappropriate acceleration operation by a driver while suppressing a sense of discomfort experienced by the driver.SOLUTION: An electronic control device 90 comprises: (a) an upper limit speed setting unit 90a which sets an upper limit speed Vup on the basis of a traveling environment; (b) a limit start speed setting unit 90c which sets a limit start speed Vst on the basis of the upper limit speed Vup; (c) a limit multiplier setting unit 90e which, on the basis of the upper limit speed Vup, the limit start speed Vst, and a vehicle speed V, calculates a multiplier α as 1 when the vehicle speed V equals the limit start speed Vst, calculates the multiplier α as zero when the vehicle speed V equals the upper limit speed Vup, and gradually decreases the multiplier α as the vehicle speed V approaches the upper limit speed Vup from the limit start speed Vst; and (d) a drive force control unit 90f which limits a drive torque Tr by multiplying a basic required drive torque Trdem corresponding to an accelerator opening θacc by the multiplier α.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vehicle speed limiting device that limits the vehicle speed to a maximum speed.

Background Art

[0002] There is known a vehicle speed limiting device that limits the vehicle speed to a maximum speed so that the vehicle speed does not exceed the maximum speed due to an inappropriate acceleration operation by the driver. For example, the one described in Patent Document 1 is such a device. The vehicle speed limiting device described in Patent Document 1 performs speed limit control based on the difference between the maximum speed and the vehicle speed before the vehicle speed reaches the maximum speed even if an inappropriate acceleration operation is performed by the driver, and prevents the vehicle speed from exceeding the maximum speed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the vehicle speed limiting device described in Patent Document 1, based on the difference between the maximum speed and the vehicle speed, the upper limit value of the vehicle acceleration is set to a smaller value as the difference becomes smaller, and the vehicle acceleration is suppressed so that the actual vehicle acceleration does not exceed the upper limit value. For this reason, for example, even when the vehicle accelerates without an acceleration operation by the driver on a downhill road or the like, the vehicle acceleration is suppressed, and the driver may feel a sense of discomfort due to the deviation from the driving feeling.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a vehicle speed limiting device that can suppress the vehicle speed from exceeding the maximum speed due to an inappropriate acceleration operation by the driver while suppressing the driver's sense of discomfort.

Means for Solving the Problems

[0006] The gist of the present invention is a vehicle speed limiting device that limits the vehicle speed to a maximum speed, comprising: (a) a maximum speed setting unit that sets the maximum speed based on the driving environment; (b) a limit start speed setting unit that sets a limit start speed based on the maximum speed; (c) a limit multiplier calculation unit that calculates the limit multiplier based on the maximum speed, the limit start speed, and the vehicle speed, calculates the limit multiplier as 1 when the vehicle speed and the limit start speed are equal, calculates the limit multiplier as zero when the vehicle speed and the maximum speed are equal, and calculates the limit multiplier by gradually decreasing it as the vehicle speed approaches the maximum speed from the limit start speed; and (d) a driving force limiting unit that multiplies the required driving force corresponding to the driver's acceleration operation amount by the limit multiplier to limit the driving force.

Advantages of the Invention

[0007] According to the present invention, there are provided: (a) a maximum speed setting unit that sets the maximum speed based on the driving environment; (b) a limit start speed setting unit that sets a limit start speed based on the maximum speed; (c) a limit multiplier calculation unit that calculates the limit multiplier based on the maximum speed, the limit start speed, and the vehicle speed, calculates the limit multiplier as 1 when the vehicle speed and the limit start speed are equal, calculates the limit multiplier as zero when the vehicle speed and the maximum speed are equal, and calculates the limit multiplier by gradually decreasing it as the vehicle speed approaches the maximum speed from the limit start speed; and (d) a driving force limiting unit that multiplies the required driving force corresponding to the driver's acceleration operation amount by the limit multiplier to limit the driving force. By multiplying the required driving force corresponding to the driver's acceleration operation amount by the limit multiplier to limit the driving force, it is possible to suppress the discomfort felt by the driver while suppressing the vehicle speed from exceeding the maximum speed due to an inappropriate acceleration operation by the driver. Further, since the limit multiplier is gradually decreased as the vehicle speed approaches the maximum speed from the limit start speed and the limitation of the driving force is gradually strengthened, the acceleration of the vehicle is suppressed while suppressing the shock to the driver.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment

[0010] FIG. 1 is a functional block diagram showing the main part of the control function of the electronic control device 90 according to an embodiment of the present invention. The electronic control device 90 is mounted on the vehicle 10 and controls the output torque of the driving power source 20 which is a driving power source mounted on the vehicle 10.

[0011] The electronic control device 90 includes, for example, a so-called microcomputer including a CPU, a RAM, a ROM, an input / output interface, etc. The CPU performs signal processing according to a program stored in the ROM in advance while using the temporary storage function of the RAM, thereby executing various controls of the vehicle 10. Note that the electronic control device 90 corresponds to the "vehicle speed limiting device" in the present invention.

[0012] Various signals (such as selection signal Ssw, environmental information Inf, vehicle speed V [km / h], accelerator opening θacc [%] representing the amount of acceleration operation of the driver, etc.) based on the detection values by various sensors and the like (for example, selection switch 70, environmental information collection device 72, vehicle speed sensor 74, accelerator opening sensor 76, etc.) are input into the electronic control unit 90 respectively. The accelerator opening θacc corresponds to the "amount of acceleration operation" in the present invention. A power source control signal Spw for controlling the output torque output from the driving power source 20 is output from the electronic control unit 90 to the driving power source 20. In this specification, unless otherwise particularly distinguished, torque, driving force, power, and force (power) are the same.

[0013] The electronic control unit 90 controls the output torque of the driving power source 20 to suppress the vehicle speed V from exceeding the upper limit speed Vup [km / h]. The upper limit speed Vup will be described later.

[0014] The electronic control unit 90 functionally includes an upper limit speed setting unit 90a, an assumed required driving force calculation unit 90b, a limit start speed setting unit 90c, a vehicle speed determination unit 90d, a limit multiplier setting unit 90e, a driving force control unit 90f, and an operating state setting unit 90g.

[0015] The upper limit speed setting unit 90a sets a temporary upper limit speed Vup_tmp [km / h] based on the driving environment. The temporary upper limit speed Vup_tmp is a temporary upper limit speed Vup and is provisional in the process of calculating the formal upper limit speed Vup. The driving environment includes, for example, the speed limit information of the road on which the vehicle 10 is currently traveling, obstacles around the vehicle 10, the presence or absence of other vehicles traveling in front of, behind, and on the left and right of the vehicle 10, and other surrounding information about the surroundings of the vehicle 10. For example, the speed limit information is acquired based on the vehicle position information based on a GPS (Global Positioning System) signal transmitted by a GPS satellite and a car navigation device including information about the road. For example, the surrounding information is acquired by a surrounding recognition sensor composed of well-known sensors such as an infrared sensor, a camera, and a medium- and long-range radar. The driving torque Tr corresponds to the "driving force" in the present invention.

[0016] When the temporary upper limit speed Vup_tmp is set by the upper limit speed setting unit 90a, the assumed required driving force calculation unit 90b acquires the current accelerator opening θacc, and calculates the assumed required driving torque Trdem_up, which is the basic required driving torque Trdem [Nm] at the time of reaching the temporary upper limit speed Vup_tmp assuming that the current accelerator opening θacc is maintained as it is. The basic required driving torque Trdem is the driving torque Tr corresponding to the accelerator opening θacc, that is, the driving torque Tr required by the driver. The basic required driving torque Trdem corresponds to the "required driving force" in the present invention, and the assumed required driving torque Trdem_up corresponds to the "assumed required driving force" in the present invention.

[0017] FIG. 2 is a diagram for explaining a method of calculating the assumed required driving torque Trdem_up, and is an example of a driving torque map. The assumed required driving torque Trdem_up is calculated, for example, by applying the current accelerator opening θacc and the temporary upper limit speed Vup_tmp to a relationship (for example, a driving torque map) determined in advance experimentally or by design. The driving torque map is a map in which the relationship between the accelerator opening θacc and the vehicle speed V and the basic required driving torque Trdem is determined and stored in advance experimentally or by design. For example, as shown in FIG. 2, in the driving torque map, when the opening value θacc1 of the current accelerator opening θacc and the vehicle speed V reach the temporary upper limit speed Vup_tmp, the basic required driving torque Trdem is calculated as the assumed required driving torque Trdem_up.

[0018] Return to FIG. 1. When the temporary upper limit speed Vup_tmp is set by the upper limit speed setting unit 90a and the assumed required driving torque Trdem_up is calculated by the assumed required driving force calculation unit 90b, the limit start speed setting unit 90c sets a temporary limit start speed Vst_tmp [km / h] based on the temporary upper limit speed Vup_tmp and the assumed required driving torque Trdem_up. The temporary limit start speed Vst_tmp is a temporary limit start speed Vst and is provisional in the process of calculating the formal limit start speed Vst. If the difference between the temporary upper limit speed Vup_tmp and the temporary limit start speed Vst_tmp is defined as a speed difference Vc [km / h], the limit start speed setting unit 90c sets the temporary limit start speed Vst_tmp such that the speed difference Vc becomes larger as the assumed required driving torque Trdem_up is higher. The speed difference Vc is a predetermined speed difference that is determined in advance experimentally or by design, for example, based on the temporary upper limit speed Vup_tmp and the assumed required driving torque Trdem_up.

[0019] When the temporary limit start speed Vst_tmp is set by the limit start speed setting unit 90c, the upper limit speed setting unit 90a sets the upper limit speed Vup to the temporary upper limit speed Vup_tmp in any of the following cases: when the vehicle speed V is less than or equal to the temporary limit start speed Vst_tmp and the vehicle speed V is less than or equal to the current limit start speed Vst; when the vehicle speed V is greater than or equal to the temporary upper limit speed Vup_tmp and the vehicle speed V is greater than or equal to the current upper limit speed Vup; and when the absolute value of the difference ΔVup between the temporary upper limit speed Vup_tmp and the current upper limit speed Vup (=|Vup_tmp - Vup|) is less than or equal to the upper limit speed creep amount ΔVup_step [km / h] (>0). The upper limit speed creep amount ΔVup_step is a change amount of the upper limit speed Vup determined in advance experimentally or by design such that the shock to the driver remains within the allowable range even when the drive torque Tr of the vehicle 10 changes due to the change of the upper limit speed Vup. When the vehicle speed V is less than or equal to the temporary limit start speed Vst_tmp and the vehicle speed V is less than or equal to the current limit start speed Vst, since the drive torque Tr of the vehicle 10 is not restricted before and after the change of the upper limit speed Vup as described later, the drive torque Tr does not change suddenly. In this case, the multiplier α described later is "1" and does not change. When the vehicle speed V is greater than or equal to the temporary upper limit speed Vup_tmp and the vehicle speed V is greater than or equal to the current upper limit speed Vup, since the drive torque Tr of the vehicle 10 is "0" before and after the change of the upper limit speed Vup as described later, the drive torque Tr does not change suddenly. In this case, the multiplier α described later is "0" and does not change. When the absolute value of the difference ΔVup is less than or equal to the upper limit speed creep amount ΔVup_step, the multiplier α described later changes, but as described later, the change of the drive torque Tr of the vehicle 10 is limited so that the shock to the driver remains within the allowable range before and after the change of the upper limit speed Vup.

[0020] When the temporary limit start speed Vst_tmp is set by the limit start speed setting unit 90c, the upper limit speed setting unit 90a resets the upper limit speed Vup by increasing it by the upper limit speed creep amount ΔVup_step when the absolute value of the difference ΔVup exceeds the upper limit speed creep amount ΔVup_step and the difference ΔVup is a positive value, and resets the upper limit speed Vup by decreasing it by the upper limit speed creep amount ΔVup_step when the difference ΔVup is a negative value. When the absolute value of the difference ΔVup exceeds the upper limit speed creep amount ΔVup_step, the multiplier α described later changes, but since the increase and decrease of the upper limit speed Vup are limited to the upper limit speed creep amount ΔVup_step, the change in the driving torque Tr of the vehicle 10 that causes a shock to the driver before and after the change in the upper limit speed Vup is limited within an allowable range.

[0021] Thus, when changing the upper limit speed Vup, the upper limit speed setting unit 90a immediately changes the upper limit speed Vup if the multiplier α does not change before and after the change, and gradually changes the upper limit speed Vup by limiting the increase and decrease of the upper limit speed Vup to the upper limit speed creep amount ΔVup_step if the multiplier α changes before and after the change.

[0022] When the upper limit speed Vup is set by the upper limit speed setting unit 90a, the limit start speed setting unit 90c sets the limit start speed Vst to be the result of subtracting the speed difference Vc from the upper limit speed Vup. The speed difference Vc corresponds to the "difference between the upper limit speed and the limit start speed" in the present invention.

[0023] When the limit start speed Vst is set by the limit start speed setting unit 90c, the vehicle speed determination unit 90d determines whether the vehicle speed V is less than or equal to the limit start speed Vst.

[0024] The operation state setting unit 90g determines whether or not the driver's selection state matches the operation state of the function that limits the vehicle speed V to the upper limit speed Vup (hereinafter simply referred to as the "operation state"). The operation state includes an activation state and a deactivation state. The activation state is a state in which the function of limiting the vehicle speed V to the upper limit speed Vup is valid (= the function of limiting the drive torque Tr is valid). When the operation state is the activation state, if the vehicle speed V exceeds the limit start speed Vst [km / h] described later, a limit is applied to the drive torque Tr [Nm] of the vehicle 10. The deactivation state is a state in which the function of limiting the vehicle speed V to the upper limit speed Vup is invalid (= the function of limiting the drive torque Tr is invalid).

[0025] When the operation state setting unit 90g determines that the driver's selection state does not match the operation state, it switches the operation state according to the selection operation of the selection switch 70 by the driver, that is, the driver's selection state. The operation state setting unit 90g switches the operation state from one of the activation state and the deactivation state to the other on the condition that the vehicle speed V is less than or equal to the limit start speed Vst. When the vehicle speed V is less than or equal to the limit start speed Vst, no limit is applied to the drive torque Tr of the vehicle 10 regardless of whether the operation state is the activation state or the deactivation state. The operation state setting unit 90g corresponds to the "operation state switching unit" in the present invention.

[0026] The limit multiplier setting unit 90e determines whether or not the operation state is the activation state. When it is determined by the limit multiplier setting unit 90e that the operation state is the activation state and it is determined by the vehicle speed determination unit 90d that the vehicle speed V exceeds the limit start speed Vst, the limit multiplier setting unit 90e calculates the multiplier α based on the upper limit speed Vup, the limit start speed Vst, and the vehicle speed V. Note that the limit multiplier setting unit 90e corresponds to the "limit multiplier calculation unit" in the present invention, and the multiplier α corresponds to the "limit multiplier" in the present invention.

[0027] FIG. 3 is a diagram for explaining the relationship between the vehicle speed V and the number of passengers α, and is an example showing the relationship between the upper limit speed Vup and the start speed Vst of the limit and the number of passengers α. In FIG. 3, the upper limit speed values Vup1 to Vup3 are examples of the upper limit speed Vup, respectively, and the start speed values Vst1 to Vst3 are examples of the start speed Vst of the limit, respectively. When the vehicle speed V is equal to the start speed Vst of the limit, the number of passengers α is calculated as "1", and when the vehicle speed V is greater than or equal to the upper limit speed Vup, the number of passengers α is calculated as "0". At the start speed Vst of the limit, the number of passengers α is "1". Therefore, strictly speaking, the start speed Vst of the limit is not the speed at which the restriction on the driving torque Tr of the vehicle 10 starts, but when the start speed Vst of the limit is exceeded, the restriction on the driving torque Tr of the vehicle 10 starts. Further, as the vehicle speed V approaches the upper limit speed Vup from the start speed Vst of the limit, the number of passengers α is calculated by being gradually decreased. For example, in the example of FIG. 3, as the vehicle speed V approaches the upper limit speed Vup from the start speed Vst of the limit, the number of passengers α is gradually decreased linearly with respect to the vehicle speed V. In this way, when the vehicle speed V exceeds the start speed Vst of the limit, as the difference ΔV (= Vup - V) between the upper limit speed Vup and the vehicle speed V decreases, the number of passengers α is calculated by being gradually decreased. For example, the restricted number of passengers setting unit 90e calculates the number of passengers α based on the difference ΔV between the upper limit speed Vup and the vehicle speed V and the start speed Vst of the limit.

[0028] For example, when the upper limit speed Vup is the upper limit speed value Vup1 and the limit start speed Vst is the start speed value Vst1, if the vehicle speed V is less than or equal to the start speed value Vst1, the passenger number α is set to "1", if the vehicle speed V is greater than or equal to the upper limit speed value Vup1, the passenger number α is set to "0", and if the vehicle speed V is between the start speed value Vst1 and the upper limit speed value Vup1, the passenger number α is calculated by applying the current vehicle speed V to a linear function with a slope k1 [h / km] (<0) shown in Figure 3. In this case, the speed difference Vc between the upper limit speed value Vup1 and the start speed value Vst1 is the speed difference value Vc1. For example, when the upper limit speed Vup is the upper limit speed value Vup2 and the limit start speed Vst is the start speed value Vst2, if the vehicle speed V is less than or equal to the start speed value Vst2, the passenger number α is set to "1", if the vehicle speed V is greater than or equal to the upper limit speed value Vup2, the passenger number α is set to "0", and if the vehicle speed V is between the start speed value Vst2 and the upper limit speed value Vup2, the passenger number α is calculated by applying the current vehicle speed V to a linear function with a slope k2 [h / km] (<0) shown in Figure 3. Note that the absolute value of the slope k2 is greater than the absolute value of the slope k1. In this case, the speed difference Vc between the upper limit speed value Vup2 and the start speed value Vst2 is the speed difference value Vc2 (<Vc1). For example, when the upper limit speed Vup is the upper limit speed value Vup3 and the limit start speed Vst is the start speed value Vst3, if the vehicle speed V is less than or equal to the start speed value Vst3, the passenger number α is set to "1", if the vehicle speed V is greater than or equal to the upper limit speed value Vup3, the passenger number α is set to "0", and if the vehicle speed V is between the start speed value Vst3 and the upper limit speed value Vup3, the passenger number α is calculated by applying the current vehicle speed V to a linear function with a slope k3 [h / km] (<0) shown in Figure 3. Note that the absolute value of the slope k3 is greater than the absolute value of the slope k2. In this case, the speed difference Vc between the upper limit speed value Vup3 and the start speed value Vst3 is the speed difference value Vc3 (<Vc2).

[0029] For example, the slope k (specifically, the slopes k1 to k3) is calculated as follows.

[0030] In vehicle 10, the maximum value of the allowable vehicle speed V is defined as the maximum vehicle speed Vmax, and the maximum value of the allowable accelerator opening θacc is defined as the maximum opening value θaccmax. When the upper limit speed Vup of vehicle 10 is the maximum vehicle speed Vmax and the accelerator opening θacc is the maximum opening value θaccmax, the change amount of the driving torque Tr per unit change amount of the vehicle speed V when the vehicle speed V reaches the upper limit speed Vup is defined as the change amount ΔTr(Vmax, θaccmax). The change amount ΔTr(Vmax, θaccmax) is a value experimentally or designedly predetermined such that the shock to the driver is within the allowable range.

[0031] Here, the change amount ΔTr(Vmax, θaccmax) is set as the reference value kc (<0). For example, the slope k is set to be equal to the reference value kc when the vehicle speed V approaches the upper limit speed Vup from the limit start speed Vst.

[0032] When the basic required driving torque Trdem in the case where vehicle 10 is controlled by the vehicle speed V and the accelerator opening θacc is represented by the torque value Trdem(V, θacc), the assumed required driving torque Trdem_up when the upper limit speed Vup of vehicle 10 is the maximum vehicle speed Vmax and the accelerator opening θacc is the maximum opening value θaccmax is represented by the torque value Trdem(Vmax, θaccmax). For example, the slope k is set to the value {=kc × Trdem(Vmax, θaccmax) / Trdem(Vup, θacc)} obtained by multiplying the reference value kc by the torque value Trdem(Vmax, θaccmax) and then dividing by the torque value Trdem(Vup, θacc). With this set slope k, the limit start speed Vst is set such that the multiplier α becomes "0" at the upper limit speed Vup. In this way, the higher the assumed required driving torque Trdem_up{=Trdem(Vup, θacc)} is, the lower the limit start speed Vst is set by the slope k.

[0033] Return to FIG. 1. When the limit multiplier setting unit 90e determines that the operating state is the enabled state, and when the vehicle speed determination unit 90d determines that the vehicle speed V exceeds the limit start speed Vst and the passenger number α is calculated by the limit multiplier setting unit 90e, the driving force control unit 90f calculates the basic required driving torque Trdem using the above-described driving torque map, and then multiplies the basic required driving torque Trdem by the passenger number α to calculate the final required driving torque Trdem_fin [Nm], and controls the output torque of the driving power source 20 so that the driving torque Tr becomes the final required driving torque Trdem_fin. The final required driving torque Trdem_fin is the driving torque Tr that is adjusted to prevent the vehicle speed V from exceeding the upper limit speed Vup and that the electronic control unit 90 actually requests from the driving power source 20. The driving force control unit 90f corresponds to the "driving force limiting unit" in the present invention.

[0034] When the limit multiplier setting unit 90e determines that the operating state is the disabled state or when the vehicle speed determination unit 90d determines that the vehicle speed V is less than or equal to the limit start speed Vst, in either case, the driving force control unit 90f calculates the basic required driving torque Trdem using the above-described driving torque map, and then controls the output torque of the driving power source 20 so that the driving torque Tr becomes the basic required driving torque Trdem.

[0035] FIG. 4 is an example of a flowchart for explaining the control operation of the electronic control unit 90. The flowchart of FIG. 4 is repeatedly executed when the vehicle 10 is in the running state.

[0036] First, in step S10 (hereinafter, steps are omitted) corresponding to the function of the upper limit speed setting unit 90a, the environmental information Inf is acquired, and in S20 corresponding to the function of the upper limit speed setting unit 90a, the temporary upper limit speed Vup_tmp is calculated. After the execution of S20, in S30 corresponding to the function of the assumed required driving force calculation unit 90b, the current accelerator opening θacc is acquired, and in S40 corresponding to the function of the assumed required driving force calculation unit 90b, the assumed required driving torque Trdem_up is calculated.

[0037] After the execution of S40, in S50 corresponding to the function of the limit start speed setting unit 90c, a temporary limit start speed Vst_tmp is calculated. After the execution of S50, in S60 corresponding to the function of the upper limit speed setting unit 90a, it is determined whether the vehicle speed V is less than or equal to the temporary limit start speed Vst_tmp and the vehicle speed V is less than or equal to the previous limit start speed Vst_last [km / h]. The "previous limit start speed Vst_last" refers to the limit start speed Vst set in the previous execution of the flowchart, that is, the current limit start speed Vst. If the determination in S60 is NO, in S70 corresponding to the function of the upper limit speed setting unit 90a, it is determined whether the vehicle speed V is greater than or equal to the temporary upper limit speed Vup_tmp and the vehicle speed V is equal to the previous upper limit speed Vup_last [km / h]. The "previous upper limit speed Vup_last" refers to the upper limit speed Vup set in the previous execution of the flowchart, that is, the current upper limit speed Vup. If the determination in S70 is NO, in S80 corresponding to the function of the upper limit speed setting unit 90a, it is determined whether the difference ΔVup (= Vup_tmp - Vup_last) exceeds the upper limit speed gradual change amount ΔVup_step. If the determination in S80 is YES, in S90 corresponding to the function of the upper limit speed setting unit 90a, the upper limit speed Vup is set to the value obtained by adding the upper limit speed gradual change amount ΔVup_step to the previous upper limit speed Vup_last. If the determination in S80 is NO, in S100 corresponding to the function of the upper limit speed setting unit 90a, it is determined whether the difference between the temporary upper limit speed Vup_tmp and the previous upper limit speed Vup_last (= Vup_tmp - Vup_last) is less than "-1 × upper limit speed gradual change amount ΔVup_step". If the determination in S100 is YES, in S110 corresponding to the function of the upper limit speed setting unit 90a, the upper limit speed Vup is set to the value obtained by subtracting the upper limit speed gradual change amount ΔVup_step from the previous upper limit speed Vup_last. If the determination in S60 is YES, if the determination in S70 is YES, and if the determination in S100 is NO, in all cases, in S120 corresponding to the function of the upper limit speed setting unit 90a, the upper limit speed Vup is set to the temporary upper limit speed Vup_tmp.After the execution of S90, after the execution of S110, and after the execution of S120, in S130 corresponding to the function of the limit start speed setting unit 90c, the limit start speed Vst (= Vup - Vc) is set.

[0038] After the execution of S130, in S140 corresponding to the function of the operation state setting unit 90g, it is determined whether the selection state of the driver matches the operation state. If the determination in S140 is NO, in S150 corresponding to the function of the vehicle speed determination unit 90d, it is determined whether the vehicle speed V is less than or equal to the limit start speed Vst. If the determination in S150 is YES, the operation state is set in S300 corresponding to the function of the operation state setting unit 90g. If the determination in S140 is YES, if the determination in S150 is NO, and after the execution of S300, in S160 corresponding to the function of the vehicle speed determination unit 90d, it is determined whether the vehicle speed V exceeds the limit start speed Vst. If the determination in S160 is YES, in S170 corresponding to the function of the limit multiplier setting unit 90e, it is determined whether the operation state is the activation state. If the determination in S170 is YES, the multiplier α is calculated in S180 corresponding to the function of the limit multiplier setting unit 90e. After the execution of S180, in S190 corresponding to the function of the driving force control unit 90f, the driving torque Tr of the vehicle 10 is controlled to be the final required driving torque Trdem_fin. If the determination in S160 is NO and if the determination in S170 is NO, in S200 corresponding to the function of the driving force control unit 90f, the driving torque Tr of the vehicle 10 is controlled to be the basic required driving torque Trdem. After the execution of S190 and after the execution of S200, both return.

[0039] FIG. 5 is an example of a partial flowchart for explaining S300 of the flowchart in FIG. 4.

[0040] First, in S310, it is determined whether the operating state is the invalidated state. If the determination in S310 is YES, in S320, the operating state is switched to the validated state which is the driver's selected state. If the determination in S310 is NO, in S330, the operating state is switched to the invalidated state which is the driver's selected state. After the execution of S320 and after the execution of S330, S300 ends in both cases.

[0041] According to this embodiment, there are provided: (a) a maximum speed setting unit 90a that sets a maximum speed Vup based on the driving environment; (b) a limit start speed setting unit 90c that sets a limit start speed Vst based on the maximum speed Vup; (c) a limit multiplier setting unit 90e that calculates the multiplier α as 1 when the vehicle speed V and the limit start speed Vst are equal and calculates the multiplier α as zero when the vehicle speed V and the maximum speed Vup are equal, and calculates the multiplier α while gradually decreasing it as the vehicle speed V approaches from the limit start speed Vst to the maximum speed Vup, based on the maximum speed Vup, the limit start speed Vst, and the vehicle speed V; and (d) a driving force control unit 90f that multiplies the multiplier α by a basic required driving torque Trdem which is the driver's acceleration operation amount, i.e., the accelerator opening θacc, to limit the driving torque Tr. Since the multiplier α is multiplied by the basic required driving torque Trdem corresponding to the accelerator opening θacc to limit the driving torque Tr, it is possible to suppress the discomfort of the driver while suppressing the vehicle speed V from exceeding the maximum speed Vup due to an inappropriate acceleration operation by the driver. Further, since the multiplier α is gradually decreased as the vehicle speed V approaches from the limit start speed Vst to the maximum speed Vup and the limitation of the driving torque Tr is gradually strengthened, it is possible to suppress the shock to the driver while suppressing the acceleration of the vehicle 10.

[0042] According to this embodiment, when changing the upper limit speed Vup, if the multiplication factor α does not change before and after the change, the upper limit speed Vup is immediately changed. If the multiplication factor α changes before and after the change, the upper limit speed Vup is gradually changed. Thereby, when the upper limit speed Vup is changed with the change of the driving environment and the multiplication factor α changes before and after the change, compared with the case where the upper limit speed Vup is immediately changed, the sudden change of the driving torque Tr is suppressed, so the shock to the driver is suppressed.

[0043] According to this embodiment, the limit start speed setting unit 90c sets the limit start speed Vst based on the assumed required driving torque Trdem_up corresponding to the accelerator opening θacc at the upper limit speed Vup when it is assumed that the accelerator opening θacc is maintained. The higher the assumed required driving torque Trdem_up, the larger the speed difference Vc between the upper limit speed Vup and the limit start speed Vst. In this way, the higher the assumed required driving torque Trdem_up, the lower the limit start speed Vst is set. That is, compared with the case where the assumed required driving torque Trdem_up is low, when the assumed required driving torque Trdem_up is high, the speed difference Vc until the vehicle speed V reaches the upper limit speed Vup is increased, so that the period during which the driving torque Tr is limited is lengthened. Thereby, even when the assumed required driving torque Trdem_up is high, the multiplication factor α is gradually decreased and the driving torque Tr is gradually decreased over a long period, so that the shock to the driver is suppressed and the acceleration of the vehicle 10 is suppressed.

[0044] According to this embodiment, (a) an operating state setting unit 90g is further provided that switches the operating state between an enabling state in which the restriction of the driving torque Tr in the driving force control unit 90f is enabled and a disabling state in which the restriction of the driving torque Tr in the driving force control unit 90f is disabled in response to a selection operation by the driver, and (b) the operating state setting unit 90g switches the operating state from one of the enabling state and the disabling state to the other on the condition that the vehicle speed V is less than or equal to the restriction start speed Vst. When the vehicle speed V is less than or equal to the restriction start speed Vst, no restriction is imposed on the driving torque Tr of the vehicle 10 regardless of whether the operating state is the enabling state or the disabling state. Therefore, when the operating state is switched from one of the enabling state and the disabling state to the other on the condition that the vehicle speed V is less than or equal to the restriction start speed Vst, a sudden change in the driving torque Tr accompanying the switching of the operating state is prevented. Thereby, the shock to the driver is suppressed.

[0045] Note that the above-described is an embodiment of the present invention, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art without departing from the spirit thereof.

[0046] In the foregoing embodiment, the multiplication factor α is gradually decreased linearly with respect to the vehicle speed V as the vehicle speed V approaches from the restriction start speed Vst to the upper limit speed Vup, but the present invention is not limited to such a mode. The present invention may be in any mode of gradual decrease as long as the multiplication factor α is gradually decreased as the vehicle speed V approaches from the restriction start speed Vst to the upper limit speed Vup, not limited to a linear function.

[0047] In the foregoing embodiment, when changing the upper limit speed Vup, the upper limit speed setting unit 90a immediately changes the upper limit speed Vup if the multiplier α does not change before and after the change, and gradually changes the upper limit speed Vup if the multiplier α changes before and after the change. However, the present invention is not limited to this mode. For example, when changing the upper limit speed Vup, the upper limit speed setting unit 90a may immediately change the upper limit speed Vup even if the multiplier α changes before and after the change. Even in this mode, when the upper limit speed Vup is not changed, the discomfort of the driver is suppressed, and it is suppressed that the vehicle speed V exceeds the upper limit speed Vup due to an inappropriate acceleration operation by the driver.

[0048] In the foregoing embodiment, the limit start speed setting unit 90c sets the limit start speed Vst such that the speed difference Vc between the upper limit speed Vup and the limit start speed Vst becomes larger as the assumed required drive torque Trdem_up is higher. However, the present invention is not limited to this mode. For example, the limit start speed setting unit 90c may set the limit start speed Vst with the speed difference Vc being the same even if the assumed required drive torque Trdem_up is different. Even in such a mode, the discomfort of the driver is suppressed, and it is suppressed that the vehicle speed V exceeds the upper limit speed Vup due to an inappropriate acceleration operation by the driver.

[0049] In the foregoing embodiment, (a) an operation state setting unit 90g for switching the operation state between an activation state and an inactivation state in response to a selection operation by the driver is further provided, and (b) the operation state setting unit 90g switches the operation state from one of the activation state and the inactivation state to the other on the condition that the vehicle speed V is equal to or lower than the limit start speed Vst. However, the present invention is not limited to such a mode. For example, the operation state setting unit 90g may switch the operation state from one of the activation state and the inactivation state to the other regardless of whether the vehicle speed V is equal to or lower than the limit start speed Vst. Even in such a mode, when the operation state is the activation state, the discomfort of the driver is suppressed, and it is suppressed that the vehicle speed V exceeds the upper limit speed Vup due to an inappropriate acceleration operation by the driver.

Explanation of Reference Numerals

[0050] 90: Electronic control device (vehicle speed limiter), 90a: Upper limit speed setting unit, 90c: Limiting start speed setting unit, 90e: Limiting multiplier setting unit (limiting multiplier calculation unit), 90f: Driving force control unit (driving force limiting unit), 90g: Operating state setting unit (operating state switching unit), Tr: Driving torque (driving force), Trdem: Basic required driving torque (required driving force), Trdem_up: Assumed required driving torque (assumed required driving force), V: Vehicle speed, Vc: Speed difference (difference between upper limit speed and limiting start speed), Vst: Limiting start speed, Vup: Upper limit speed, α: Multiplier (limiting multiplier), θacc: Accelerator opening (acceleration operation amount)

Claims

1. A vehicle speed limiting device that limits the vehicle speed to a maximum speed, comprising: a maximum speed setting unit that sets the maximum speed based on the driving environment; a limit start speed setting unit that sets a limit start speed based on the maximum speed; a limit multiplier calculation unit that calculates the limit multiplier based on the maximum speed, the limit start speed, and the vehicle speed, calculates the limit multiplier as 1 when the vehicle speed and the limit start speed are equal, calculates the limit multiplier as 0 when the vehicle speed and the maximum speed are equal, and calculates the limit multiplier to gradually decrease as the vehicle speed approaches the maximum speed from the limit start speed; a driving force limiting unit that multiplies the required driving force corresponding to the driver's acceleration operation amount by the limit multiplier to limit the driving force. A vehicle speed limiting device characterized by the above.

2. When changing the maximum speed, the maximum speed setting unit immediately changes the maximum speed if the limit multiplier does not change before and after the change, and gradually changes the maximum speed if the limit multiplier changes before and after the change. The vehicle speed limiting device according to claim 1, characterized by the above.

3. The limit start speed setting unit sets the limit start speed based on an assumed required driving force corresponding to the acceleration operation amount at the maximum speed when it is assumed that the acceleration operation amount is maintained, such that the difference between the maximum speed and the limit start speed increases as the assumed required driving force increases. The vehicle speed limiting device according to claim 1, characterized by the above.

4. The vehicle speed limiting device further comprises an operating state switching unit that switches the operating state between an enabling state in which the driving force limitation in the driving force limiting unit is enabled and a disabling state in which the driving force limitation in the driving force limiting unit is disabled according to the driver's selection operation. The operating state switching unit switches the operating state from one of the enabling state and the disabling state to the other on the condition that the vehicle speed is less than or equal to the limit start speed. The vehicle speed limiting device according to any one of claims 1 to 3, characterized by the above.

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