JP7722303B2 - Vehicle shock detection device - Google Patents

Description

The present invention relates to a shock determination device for a vehicle equipped with an engine and an electric motor as power sources.

Vehicles equipped with an engine and an electric motor as power sources are known that detect shocks that may occur during automatic engine start control. For example, the vehicle described in Patent Document 1 is one such vehicle. The vehicle described in Patent Document 1 is equipped with an idling stop system, for example, and detects whether or not engine start shocks will occur when the engine is automatically started while the vehicle is stopped.

Japanese Patent Application Laid-Open No. 2001-55943

In vehicles equipped with an engine and an electric motor as power sources, the engine may be automatically started or stopped while the vehicle is in motion. In this case, accurately determining whether a shock is caused by engine start or engine stop requires that the shock is not caused by driving on a rough road. For example, a method can be considered in which a sudden change in wheel speed is used to detect that the vehicle is driving on a rough road and not determine that a shock occurring while driving on a rough road is caused by engine start or other factors. However, although the occurrence of a shock caused by driving on a rough road and the change in wheel speed occur approximately simultaneously, a change in wheel speed may occur after the shock occurs, depending on the road surface conditions. Therefore, if driving on a rough road begins immediately after automatic engine start control is initiated, there is a risk that a shock caused by driving on a rough road may be erroneously determined to be caused by engine start. In particular, compared to continuous driving on rough roads, shocks occurring during isolated driving on rough roads, such as when driving over a bump, are more likely to be erroneously determined.

The present invention was made against the background of the above circumstances, and its purpose is to provide a shock determination device for a vehicle that can reduce the erroneous determination that a shock caused by driving on rough roads is a shock caused by engine start or engine stop.

The gist of the present invention is a shock determination device for a vehicle equipped with an engine and an electric motor as power sources, capable of switching between engine running, which uses at least the engine as a power source, and electric motor running, which uses only the electric motor as a power source. During at least one of the engine start control period and stop control period accompanying the switching of the power source from one of electric motor running and engine running to the other, (a) if the acceleration in the longitudinal direction of the vehicle exceeds a predetermined first determination value and a wheel speed change amount, which is the amount of change in wheel speed, exceeds a predetermined second determination value within a predetermined period from the point at which the acceleration exceeds the first determination value, the device does not determine that a start shock or a stop shock of the engine has occurred based on the acceleration exceeding the first determination value; and (b) if the acceleration exceeds the first determination value and the wheel speed change amount does not exceed the second determination value within the predetermined period, the device determines that a start shock or a stop shock of the engine has occurred based on the acceleration exceeding the first determination value.

According to the shock determination device of the present invention, (a) if the acceleration in the longitudinal direction of the vehicle exceeds a predetermined first determination value and a wheel speed change amount, which is the amount of change in wheel speed, exceeds a predetermined second determination value within a predetermined period from the time the acceleration exceeds the first determination value, it is not determined that an engine start-up shock or engine stop shock has occurred based on the acceleration exceeding the first determination value; and (b) if the acceleration exceeds the first determination value and the wheel speed change amount does not exceed the second determination value within the predetermined period, it is determined that an engine start-up shock or engine stop shock has occurred based on the acceleration exceeding the first determination value. Even when driving on a rough road where a change in wheel speed appears after the occurrence of a shock, erroneous determination that a shock caused by driving on a rough road is a shock caused by engine start-up or engine stop is suppressed.

1 is a schematic diagram illustrating an example of a vehicle equipped with an electronic control device according to a first embodiment; 2 is an example of a flowchart illustrating a control operation of the electronic control device shown in FIG. 1 during an engine start control period. 3 is a time chart when the flowchart of FIG. 2 is executed, showing an example in which the wheel speed change detection signal is turned on after the shock detection signal is turned on. 3 is a time chart when the flowchart of FIG. 2 is executed, showing an example in which the shock detection signal is turned on after the wheel speed change detection signal is turned on. 10 is an example of a flowchart illustrating a control operation of an electronic control device according to a second embodiment during an engine stop control period.

Each embodiment of the present invention will be described in detail below with reference to the drawings. Note that in each of the following embodiments, the drawings have been simplified or modified as appropriate, and the dimensional ratios and shapes of each part are not necessarily drawn accurately.

Figure 1 is an example of a schematic configuration diagram of a vehicle 10 equipped with an electronic control device 90 according to the first embodiment.

The vehicle 10 is a hybrid vehicle equipped with an engine 12, a first electric motor MG1, and a second electric motor MG2, which function as power sources. In the power transmission path PT between the engine 12 and a pair of drive wheels 32, the vehicle 10 is connected, in order from the engine 12 side, to an engine connecting shaft 22, a differential unit 34, an automatic transmission input shaft 26, an automatic transmission 18, an automatic transmission output shaft 28, a differential 40, and a pair of axles 30, all of which are well-known components. The vehicle 10 also includes a hydraulic control circuit 50, an inverter 60, a battery 62, and an electronic control unit 90.

The engine 12 is a well-known internal combustion engine. The first electric motor MG1 and the second electric motor MG2 are, for example, rotating electric machines that have both an electric motor function and a generator function, and are so-called motor generators. Note that the first electric motor MG1 and the second electric motor MG2 may be rotating electric machines that do not have a generator function, as long as they have an electric motor function.

The differential unit 34 is composed of, for example, a single-pinion planetary gear device, and the sun gear S0, carrier CA0, and ring gear R0 are connected to the first electric motor MG1, the engine 12 via the engine connecting shaft 22, and the AT input shaft 26 via the intermediate transmission shaft 36, respectively. The differential unit 34 is a power split mechanism that mechanically splits the power output from the engine 12 between the first electric motor MG1 and the intermediate transmission shaft 36. For example, the first electric motor MG1 generates electricity using the power of the engine 12 split by the first electric motor MG1, and the generated electrical energy is stored in the battery 62 via the inverter 60 or is used to rotate the second electric motor MG2. The differential unit 34 functions as an electric differential unit (electric continuously variable transmission) in which the gear ratio γdif (= rotational speed [rpm] of the engine connecting shaft 22 / rotational speed [rpm] of the intermediate transmission shaft 36) can be continuously changed by controlling the output torque of the first electric motor MG1. The second electric motor MG2 is connected to the intermediate transmission shaft 36 so as to be able to transmit power.

The automatic transmission 18 is a well-known planetary gear automatic transmission equipped with, for example, one or more planetary gear devices (not shown) and an engagement device CB. The engagement device CB includes, for example, a plurality of well-known hydraulic friction engagement devices. The automatic transmission 18 is a stepped transmission in which one of a plurality of gear stages (also referred to as gear ratios) with different speed ratios (also referred to as gear stages) γat (= AT input shaft rotation speed Nin [rpm] / AT output shaft rotation speed Nout [rpm]) is formed by engaging one of the engagement devices CB. The AT input shaft rotation speed Nin is the rotation speed of the AT input shaft 26, which is the input shaft of the automatic transmission 18, and the AT output shaft rotation speed Nout is the rotation speed of the AT output shaft 28, which is the output shaft of the automatic transmission 18.

The hydraulic control circuit 50 uses the hydraulic pressure of the hydraulic oil discharged from a mechanical oil pump or electric oil pump (not shown) as the source pressure and supplies adjusted hydraulic pressure to the actuators that control the control state (engaged state, disengaged state) of the engagement devices CB of the automatic transmission 18. The hydraulic control circuit 50 also supplies hydraulic oil as a lubricant to parts such as gears provided in the power transmission path PT.

The inverter 60 is a power supply circuit provided between the first electric motor MG1, the second electric motor MG2, and the battery 62, and is controlled by the electronic control device 90 to convert DC to AC and vice versa. The output torque of the first electric motor MG1, MG1 output torque Tmg1 [Nm], and the output torque of the second electric motor MG2, MG2 output torque Tmg2 [Nm], are each controlled by the inverter 60, which is controlled by the electronic control device 90.

The battery 62 is a rechargeable secondary battery, such as a lithium-ion battery or a nickel-metal hydride battery. The battery 62 is primarily used to supply power to drive the first electric motor MG1 and the second electric motor MG2, which serve as the power source, and to store the power generated by the first electric motor MG1 and the second electric motor MG2 through regeneration.

The electronic control unit 90 is a controller that includes control devices that control various parts within the vehicle 10, and is configured to include, for example, a so-called microcomputer in which the CPU processes signals according to a program pre-stored in ROM while utilizing the temporary storage function of RAM. The electronic control unit 90 corresponds to the "shock determination device" of the present invention.

The electronic control unit 90 receives various signals (e.g., accelerator opening θacc [%], which is the driver's accelerator operation amount indicating the magnitude of the driver's acceleration operation, wheel speed Nr [rpm], which is the rotational speed of each front wheel and rear wheel, engine rotation speed Ne [rpm], which is the rotational speed of the engine 12, MG1 rotation speed Nmg1 [rpm], which is the rotational speed of the first electric motor MG1, MG2 rotation speed Nmg2 [rpm], which is the rotational speed of the second electric motor MG2, acceleration Gx [m/sec2], which is the acceleration in the longitudinal direction of the vehicle 10) based on detection values from various sensors provided on the vehicle 10 (e.g., accelerator opening sensor 70, wheel speed sensors 72 provided for each front wheel and rear wheel, engine rotation speed sensor 74, MG1 rotation speed sensor 76, MG2 rotation speed sensor 78, acceleration sensor ⁸⁰ , etc.). The acceleration Gx is the amount of change per unit time in the longitudinal speed [m/sec] of the vehicle 10, expressed as an absolute value. Therefore, the acceleration Gx also includes the absolute value of the deceleration (negative acceleration) in the longitudinal direction of the vehicle 10. The acceleration Gx corresponds to the "acceleration" in the present invention.

The electronic control unit 90 outputs various command signals (e.g., an engine control signal Se for controlling the engine 12, an MG1 control signal Smg1 and an MG2 control signal Smg2 for controlling the first electric motor MG1 and the second electric motor MG2, and a hydraulic control signal Sp for controlling the engagement and disengagement of the engagement device CB) to each device (e.g., the engine 12, the inverter 60, the hydraulic control circuit 50, etc.) provided in the vehicle 10.

The vehicle 10 can select either an electric motor driving mode or an engine driving mode. The electric motor driving mode is a driving mode in which the vehicle drives as a battery electric vehicle (BEV) using at least one of the first electric motor MG1 and the second electric motor MG2 as a power source while the engine 12, one of the power sources, is stopped. The engine driving mode is a driving mode in which the vehicle drives as a hybrid electric vehicle (HEV) using at least the engine 12 as a power source. When switching from the electric motor driving mode to the engine driving mode, engine start control is executed to automatically start the engine 12. When switching from the engine driving mode to the electric motor driving mode, engine stop control is executed to automatically stop the engine 12.

Figure 2 is an example of a flowchart illustrating the control operation of the electronic control device 90 shown in Figure 1 during the start control period of the engine 12. Hereinafter, the "start control period of the engine 12" will be referred to simply as the "start control period." The flowchart in Figure 2 is repeatedly executed during electric motor driving and during the start control period. Figure 2 illustrates a case where the engine 12 is automatically started, for example, in an electric motor driving mode that uses only the second electric motor MG2 as a power source. In this case, the second electric motor MG2 corresponds to the "electric motor" in this invention.

First, in step S10 (hereinafter, "step" will be omitted), it is determined whether the vehicle is currently in the startup control period. If the determination in S10 is affirmative, it is determined in step S20 whether the acceleration Gx is equal to or greater than the determination value Gx_jdg, i.e., whether a shock in the longitudinal direction of the vehicle 10 has occurred. The startup control period is the period during which a shock resulting from starting the engine 12 (hereinafter referred to as "engine startup shock") may occur, for example, the period during which engine startup control is being executed (i.e., the period from start point P1 to end point P2 of engine startup control shown in Figures 3 and 4). The determination value Gx_jdg is a determination value of acceleration Gx that is determined experimentally or by design in advance to determine whether the shock occurring is outside the acceptable range for vehicle occupants, including the driver. The determination value Gx_jdg corresponds to the "predetermined first determination value" in this invention.

If the determination in S20 is affirmative, in S30, a temporary non-determination period Tmsk_tmp [sec] is set from the time when the acceleration Gx becomes equal to or greater than the determination value Gx_jdg. The temporary non-determination period Tmsk_tmp serves as a grace period for determining whether or not the engine start shock is occurring. The temporary non-determination period Tmsk_tmp is the maximum delay time from the time when the acceleration Gx is detected as being equal to or greater than the determination value Gx_jdg due to rough road driving to the time when the wheel speed change amount ΔNr [rpm/sec], described below, is detected as being equal to or greater than the determination value ΔNr_jdg, and is a period determined in advance experimentally or by design. Therefore, regardless of the road surface conditions of the rough road on which the vehicle 10 is traveling, the wheel speed change amount ΔNr will not be detected as being equal to or greater than the determination value ΔNr_jdg after the temporary non-determination period Tmsk_tmp has elapsed from the time when the acceleration Gx is detected as being equal to or greater than the determination value Gx_jdg.

After execution of S30, S40 determines whether the wheel speed change amount ΔNr is equal to or greater than a criterion value ΔNr_jdg within a temporary non-determination period Tmsk_tmp. The wheel speed change amount ΔNr is the amount of change in the wheel speed Nr per unit time expressed as an absolute value. Preferably, the wheel speed change amount ΔNr is the largest amount of change per unit time among the amounts of change in the wheel speed Nr per unit time for the front and rear wheels. The criterion value ΔNr_jdg is a criterion value determined in advance through experimentation or design considerations in order to determine whether the wheel speed change amount ΔNr caused by traveling on a rough road is due to traveling on a rough road. The criterion value ΔNr_jdg corresponds to the "predetermined second criterion value" in this invention. If the wheel speed change amount ΔNr is less than the criterion value ΔNr_jdg and no engine start shock occurs, the acceleration Gx is less than the criterion value Gx_jdg.

If the determination in S40 is positive, in S50, the temporary non-determination period Tmsk_tmp is set as the first non-determination period Tmsk1 [sec], which is the actual non-determination period, and the period from the time when it is determined in S40 that the wheel speed change amount ΔNr is equal to or greater than the determination value ΔNr_jdg to the end point P2 of engine start control is set as the second non-determination period Tmsk2 [sec]. If the determination in S40 is positive, the shock detected in S20 may have been caused by traveling on a rough road. By setting the temporary non-determination period Tmsk_tmp as the first non-determination period Tmsk1 [sec], the shock detected in S20 is not determined to be an engine start shock. By setting the second non-determination period Tmsk2, it is not determined that an engine start shock has occurred even if the acceleration Gx becomes equal to or greater than the determination value Gx_jdg during this period.

If the determination in S40 is negative, the temporary non-determination period Tmsk_tmp is not set to the actual non-determination period in S60. As a result, the shock detected in S20 is determined to be an engine start shock.

If the determination in S20 is negative, then in S70 it is determined whether the wheel speed change amount ΔNr is equal to or greater than the determination value ΔNr_jdg. If the determination in S70 is positive, then in S80 the period from the point in time when it is determined in S70 that the wheel speed change amount ΔNr is equal to or greater than the determination value ΔNr_jdg to the end point P2 of the engine start control is set as a second non-determining period Tmsk2. By setting the second non-determining period Tmsk2, it is not determined that an engine start shock has occurred even if the acceleration Gx is equal to or greater than the determination value Gx_jdg during this period. If the determination in S10 is negative, after S50 is executed, after S60 is executed, if the determination in S70 is negative, or after S80 is executed, then the process returns.

For example, if S60 determines that the shock detected in S20 is an engine start shock, the control content is changed in the next engine start control to make it less likely for engine start shock to occur. For example, by lengthening the cranking period, the engine 12 is ignited after the engine rotation speed Ne has approached the rotation speed corresponding to the AT input shaft rotation speed Nin while driving, thereby reducing engine start shock.

Figure 3 is a time chart showing the execution of the flowchart in Figure 2, illustrating an example in which the wheel speed change detection signal Snr turns on after the shock detection signal Ssh turns on.

The shock detection signal Ssh is a signal that detects a shock occurring in the vehicle 10, and specifically, is in the ON state while the acceleration Gx is equal to or greater than the judgment value Gx_jdg. In other words, the shock detection signal Ssh being in the ON state means that a shock occurring in the vehicle 10 has been detected. The wheel speed change detection signal Snr is a signal that detects a wheel speed change due to rough road driving, and specifically, is in the ON state while the wheel speed change amount ΔNr is equal to or greater than the judgment value ΔNr_jdg. In other words, the wheel speed change detection signal Snr being in the ON state means that the wheel speed change amount ΔNr is equal to or greater than the judgment value ΔNr_jdg. The startup shock detection flag Fsh_eng is a flag signal that indicates that the shock detected by the shock detection signal Ssh is an engine startup shock. In other words, the startup shock detection flag Fsh_eng being in the ON state means that the shock detected by the shock detection signal Ssh has been determined to be an engine startup shock.

In Figure 3, the solid lines for the wheel speed change detection signal Snr, the second non-determination period setting signal Smsk2, and the starting shock detection flag Fsh_eng represent an example where the wheel speed change detection signal Snr is in the ON state during the temporary non-determination period Tmsk_tmp. On the other hand, the dashed lines represent an example where the wheel speed change detection signal Snr does not become ON during the temporary non-determination period Tmsk_tmp, but becomes ON after the temporary non-determination period Tmsk_tmp has elapsed.

First, we will explain the case where the wheel speed change detection signal Snr is in the ON state (solid line) during the temporary non-determination period Tmsk_tmp.

At start point P1, engine start control is initiated. A longitudinal shock occurs in the vehicle 10, causing the acceleration Gx to exceed the determination value Gx_jdg during the period from time t1 to time t2. This causes the shock detection signal Ssh to be in the ON state during the period from time t1 to time t2. Based on the change of the shock detection signal Ssh to the ON state at time t1, the temporary non-determination period setting signal Smsk_tmp is in the ON state from time t1. In other words, the period from time t1 to time t5 is set as the temporary non-determination period Tmsk_tmp.

During this temporary non-determination period Tmsk_tmp, from time t3 (t1 < t3 < t5) to time t4, the wheel speed change detection signal Snr is in the ON state, i.e., the wheel speed change amount ΔNr is equal to or greater than the determination value ΔNr_jdg. Based on the wheel speed change detection signal Snr turning ON at time t3 within the temporary non-determination period Tmsk_tmp, a signal similar to the temporary non-determination period setting signal Smsk_tmp is output as the first non-determination period setting signal Smsk1. In other words, the temporary non-determination period Tmsk_tmp is set as the actual non-determination period. Furthermore, based on the wheel speed change detection signal Snr turning ON at time t3, the second non-determination period setting signal Smsk2 is set to the ON state for the period from time t3 to the end point P2 of the engine start control. As a result, the period from time t3 to the end point P2 is set as the second non-determination period Tmsk2. By setting the temporary non-determination period Tmsk_tmp as the first non-determination period Tmsk1, the shock detection signal Ssh detected during the period from time t1 to time t2 is considered to be within the actual non-determination period. As a result, the startup shock detection flag Fsh_eng is set to the OFF state for the period from time t1 to time t2. In other words, the shock detected in the shock detection signal Ssh during the period from time t1 to time t2 is not determined to be an engine startup shock.

Next, we will explain the case where the wheel speed change detection signal Snr does not turn on during the temporary non-determination period Tmsk_tmp, but turns on after the temporary non-determination period Tmsk_tmp has elapsed (the case indicated by the dashed line).

The wheel speed change detection signal Snr is in the ON state from time t6 (t5 < t6) after the elapse of the temporary non-determination period Tmsk_tmp to time t7. Based on the change of the wheel speed change detection signal Snr to the ON state at time t6 after the elapse of the temporary non-determination period Tmsk_tmp, the temporary non-determination period Tmsk_tmp is not set as the first non-determination period Tmsk1. In other words, the temporary non-determination period Tmsk_tmp is not set as an actual non-determination period. Furthermore, based on the change of the wheel speed change detection signal Snr to the ON state at time t6, the second non-determination period setting signal Smsk2 is set to the ON state for the period from time t6 to the end point P2 of the engine start control. As a result, the period from time t6 to the end point P2 is set as the second non-determination period Tmsk2. Because the temporary non-determination period Tmsk_tmp is not set as the first non-determination period Tmsk1, the shock detection signal Ssh detected during the period from time t1 to time t2 is not judged as non-determination, and the startup shock detection flag Fsh_eng is set to the ON state. In other words, the shock detection signal Ssh detected during the period from time t1 to time t2 is judged to be an engine startup shock after the grace period for judgment set as the temporary non-determination period Tmsk_tmp has elapsed.

Figure 4 is a time chart when the flowchart of Figure 2 is executed, showing an example of when the shock detection signal Ssh turns on after the wheel speed change detection signal Snr turns on. The time chart of Figure 4 is substantially the same as the time chart of Figure 3, so the following explanation will focus on the differences from Figure 3. Essentially common parts are given the same reference numerals and will not be explained further.

At time t11 (t11 < t1), before the shock detection signal Ssh turns ON at time t1, the wheel speed change detection signal Snr turns ON. The wheel speed change detection signal Snr is ON from time t11 to time t12. Based on the wheel speed change detection signal Snr turning ON at time t11, the second non-determination period setting signal Smsk2 is turned ON for the period from time t11 to the end point P2 of the engine start control. This sets the period from time t11 to the end point P2 as the second non-determination period Tmsk2. By setting the second non-determination period Tmsk2, the shock detection signal Ssh detected from time t1 to time t2 is within the actual non-determination period. As a result, the startup shock detection flag Fsh_eng is turned OFF for the period from time t1 to time t2. In other words, a shock detected in the shock detection signal Ssh during the period from time t1 to time t2 is not determined to be an engine start shock.

According to this embodiment, in a vehicle 10 that has an engine 12 and a second electric motor MG2 as power sources and that can switch between engine running using at least the engine 12 as a power source and electric motor running using only the second electric motor MG2 as a power source, the electronic control unit 90 of the vehicle 10, during the start-up control period accompanying the switching of the power source from electric motor running to engine running, (a) if the acceleration Gx of the vehicle 10 becomes equal to or greater than the judgment value ΔNr_jdg and the wheel speed change amount ΔNr becomes equal to or greater than the judgment value ΔNr_jdg within the provisional non-determination period Tmsk_tmp, does not determine that an engine start-up shock has occurred based on the acceleration Gx becoming equal to or greater than the judgment value ΔNr_jdg, and (b) if the acceleration Gx becomes equal to or greater than the judgment value ΔNr_jdg and the wheel speed change amount ΔNr does not become equal to or greater than the judgment value ΔNr_jdg within the provisional non-determination period Tmsk_tmp, determines that an engine start-up shock has occurred based on the acceleration Gx becoming equal to or greater than the judgment value ΔNr_jdg. Even when driving on rough roads where a change in wheel speed Nr occurs after a shock occurs, erroneous determination that a shock caused by driving on rough roads is an engine start shock is suppressed.

According to this embodiment, during the startup control period, (a) if the acceleration Gx exceeds the reference value ΔNr_jdg, a predetermined period is set as a provisional non-determination period Tmsk_tmp during which it is not temporarily determined whether or not an engine startup shock has occurred; (b) if the wheel speed change amount ΔNr exceeds the reference value ΔNr_jdg during the provisional non-determination period Tmsk_tmp, the provisional non-determination period Tmsk_tmp becomes the actual non-determination period; and (b) if the wheel speed change amount ΔNr does not exceed the reference value ΔNr_jdg during the provisional non-determination period Tmsk_tmp, the provisional non-determination period Tmsk_tmp is not the actual non-determination period. In this way, after the provisional non-determination period Tmsk_tmp is set, whether or not the provisional non-determination period Tmsk_tmp becomes the actual non-determination period is determined depending on whether the wheel speed change amount ΔNr exceeds the reference value ΔNr_jdg during the provisional non-determination period Tmsk_tmp. This makes it easier to determine whether or not engine start-up shock has occurred, reducing erroneous determinations by the electronic control unit 90.

According to this embodiment, if the wheel speed change amount ΔNr becomes equal to or greater than the judgment value ΔNr_jdg during the startup control period, it is not determined that an engine startup shock has occurred, even if the acceleration Gx becomes equal to or greater than the judgment value Gx_jdg during the second non-determination period Tmsk2, which is from the time when the wheel speed change amount ΔNr becomes equal to or greater than the judgment value ΔNr_jdg (for example, time t3 or time t11) to the end point P2 of the startup control period. When the wheel speed change amount ΔNr becomes equal to or greater than the judgment value ΔNr_jdg, erroneous determination that a shock caused by continuous rough road driving is an engine startup shock is suppressed.

Figure 5 is an example of a flowchart illustrating the control operation of the electronic control device 90 according to Example 2 during a stop control period for the engine 12. Hereinafter, the "stop control period for the engine 12" will be simply referred to as the "stop control period." This Example is substantially the same as Example 1 described above, except that while Example 1 was a control operation during a start control period, this Example is a control operation during a stop control period. Therefore, the following description will focus on the differences from Example 1, and essentially common parts will be denoted by the same reference numerals and will not be described as appropriate. The flowchart in Figure 5 is repeatedly executed during engine running and during the stop control period. Figure 5 illustrates a case in which the engine 12 is automatically stopped, for example, in an engine running mode in which both the engine 12 and the second electric motor MG2 are used as power sources. In this case, the second electric motor MG2 corresponds to the "electric motor" in this invention.

First, in S110, it is determined whether or not the vehicle is in a stop control period. If the determination in S110 is positive, in S120 it is determined whether the acceleration Gx is equal to or greater than the determination value Gx_jdg, i.e., whether or not a shock has occurred in the longitudinal direction of the vehicle 10. The stop control period is a period during which a shock caused by stopping the engine 12 (hereinafter referred to as "engine stop shock") may occur, for example, a period during which engine stop control is being executed (= the period from the start to the end of engine stop control).

If the determination in S120 is positive, in S130, a temporary non-determining period Tmsk_tmp is set from the point at which the acceleration Gx becomes equal to or greater than the determination value Gx_jdg. After S130 is executed, in S140, it is determined whether the wheel speed change amount ΔNr becomes equal to or greater than the determination value ΔNr_jdg within the temporary non-determining period Tmsk_tmp.

If the determination in S140 is positive, in S150, the temporary non-determination period Tmsk_tmp is set as the actual non-determination period as the first non-determination period Tmsk1, and the period from the time when it is determined in S140 that the wheel speed change amount ΔNr is equal to or greater than the determination value ΔNr_jdg to the time when engine stop control ends is set as the second non-determination period Tmsk2. If the determination in S140 is positive, the shock detected in S120 may have been caused by driving on a rough road, so the shock detected in S120 is not determined to be an engine stop shock. If the determination in S140 is negative, in S160, the temporary non-determination period Tmsk_tmp is not set as the actual non-determination period. As a result, the shock detected in S120 is determined to be an engine stop shock.

If the determination in S120 is negative, then in S170 it is determined whether the wheel speed change amount ΔNr is equal to or greater than the determination value ΔNr_jdg. If the determination in S170 is positive, then in S180 the period from the time it is determined in S170 that the wheel speed change amount ΔNr is equal to or greater than the determination value ΔNr_jdg to the time engine stop control ends is set as the second non-determination period Tmsk2. If the determination in S110 is negative, after S150 is executed, after S160 is executed, if the determination in S170 is negative, or after S180 is executed, the process returns.

For example, if S160 determines that the shock detected in S120 is an engine stop shock, the control content will be changed in the next engine stop control so that an engine stop shock is less likely to occur.

The only difference between this embodiment and the first embodiment is that control is performed during the start control period, whereas control is performed during the stop control period. Therefore, even when driving on a rough road where a change in wheel speed Nr occurs after a shock occurs, the same effects as those of the first embodiment can be achieved, such as suppressing erroneous determinations that shocks caused by driving on a rough road are engine stop shocks.

The above are examples of the present invention, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art, without departing from the spirit of the invention.

In the above-described first and second embodiments, the "electric motor driving" of the present invention uses only the second electric motor MG2 as the power source, but it may also use, for example, only the first electric motor MG1 as the power source.

In the above-mentioned Examples 1 and 2, a temporary non-determining period Tmsk_tmp is set from the time when the shock detection signal Ssh changes to the ON state, and if the wheel speed change amount ΔNr becomes equal to or greater than the determination value ΔNr_jdg within that temporary non-determining period Tmsk_tmp, it is not determined that a starting shock or stopping shock of the engine 12 has occurred, but the present invention is not limited to this. For example, regardless of whether the wheel speed change amount ΔNr becomes equal to or greater than the judgment value ΔNr_jdg within the hypothetical non-judgment period Tmsk_tmp, the shock detected in S20 of the flowchart in FIG. 2 or S120 of the flowchart in FIG. 5 may not be judged to be an engine start shock in any of the following cases: (1) the friction coefficient μ of the road surface on which the vehicle 10 is traveling is equal to or less than a predetermined coefficient value μ_jdg, making it a low-μ road on which the drive wheels are likely to spin (slip); (2) either the accelerator or brake is operated during the start control period or the stop control period; (3) the oil temperature THoil [°C] of the hydraulic oil supplied from the hydraulic control circuit 50 is lower than a predetermined judgment temperature THoil_jdg; (4) engine start is canceled during the start control period of the engine 12; or (5) engine stop is canceled during the stop control period of the engine 12 and the engine 12 is restarted. The predetermined coefficient value μ_jdg is a coefficient value determined experimentally or by design as the upper limit of the friction coefficient range for low-μ roads where shock may occur in the vehicle 10. The predetermined judgment temperature THoil_jdg is a judgment temperature determined experimentally or by design where shock may occur in the vehicle 10 due to insufficient lubrication by hydraulic oil in the power transmission path PT, for example. This is because shock may occur in cases (1) to (5) above, even without being caused by engine start or engine stop.

In the first and second embodiments described above, the second non-determining period Tmsk2 extends until the end point P2 of engine start control or the end point of engine stop control, but the present invention is not limited to this configuration. For example, the second non-determining period Tmsk2 may be the maximum delay time between the time when the wheel speed change amount ΔNr due to rough road driving is detected as being equal to or greater than the determination value ΔNr_jdg and the time when the acceleration Gx is detected as being equal to or greater than the determination value Gx_jdg, and may be a period determined in advance experimentally or by design. This reduces the non-determining period (i.e., the period excluded from determination) for engine start shock or engine stop shock due to rough road driving, while suppressing erroneous determinations that shocks caused by rough road driving are due to engine start or engine stop.

In the above-described first and second embodiments, the vehicle 10 has an engine 12 and two electric motors (first electric motor MG1 and second electric motor MG2) as power sources, but the present invention is not limited to this. For example, the vehicle 10 to which the present invention is applied may have an engine 12 and one electric motor as power sources and be equipped with an engagement device that connects and disconnects the power transmission between the engine 12 and the electric motor. In short, the present invention is applicable to a vehicle 10 that has an engine 12 and an electric motor as power sources and is capable of switching between engine running and electric motor running.

10: vehicle, 12: engine, 90: electronic control device (shock determination device), Gx: acceleration, Gx_jdg: determination value (predetermined first determination value), MG2: second electric motor (electric motor), Nr: wheel speed, Tmsk1: first non-determining period, Tmsk_tmp: temporary non-determining period, ΔNr: wheel speed change amount, ΔNr_jdg: determination value (predetermined second determination value)

Claims (3)

A shock determination device for a vehicle that has an engine and an electric motor as power sources and that can switch between engine running, in which at least the engine is used as a power source, and electric motor running, in which only the electric motor is used as a power source, comprising:
During at least one of a start control period and a stop control period of the engine, which accompanies switching of the power source from one of the electric motor running mode and the engine running mode to the other,
When the acceleration in the longitudinal direction of the vehicle becomes equal to or greater than a predetermined first determination value and a wheel speed change amount, which is the amount of change in wheel speed, becomes equal to or greater than a predetermined second determination value within a predetermined period from the time when the acceleration becomes equal to or greater than the first determination value, it is not determined that a start shock or a stop shock of the engine has occurred based on the acceleration becoming equal to or greater than the first determination value,
A shock determination device for a vehicle, characterized in that when the acceleration becomes equal to or greater than the first determination value and the wheel speed change amount does not become equal to or greater than the second determination value within the specified period, it is determined that a start-up shock or a stop-down shock of the engine has occurred based on the acceleration becoming equal to or greater than the first determination value. When the acceleration becomes equal to or greater than the first determination value during at least one of a start control period and a stop control period of the engine, the predetermined period is set as a temporary non-determination period during which it is not temporarily determined whether a start shock or a stop shock of the engine has occurred,
If the wheel speed change amount becomes equal to or greater than the second determination value during the provisional non-determination period, the provisional non-determination period is set as an actual non-determination period;
2. The shock determination device for a vehicle according to claim 1, wherein if the wheel speed change amount does not become equal to or greater than the second determination value within the provisional non-determination period, the provisional non-determination period is not regarded as an actual non-determination period. The shock determination device for a vehicle as described in claim 1 or 2, characterized in that if the wheel speed change amount becomes equal to or greater than the second judgment value during at least one of the engine start control period and stop control period, it is not determined that a start shock or stop shock of the engine has occurred even if the acceleration becomes equal to or greater than the first judgment value within the period from the time when the wheel speed change amount becomes equal to or greater than the second judgment value to the end of the start control period or the end of the stop control period.