Road surface determination device

Abstract

To improve the accuracy of detecting uneven road surfaces. [Solution] A road surface determination device for a hybrid vehicle that can switch between a first driving mode in which the vehicle is driven with the engine running and a second driving mode in which the vehicle is driven using power from the motor with the engine stopped, which determines whether or not the road surface is uneven when the vehicle is driving, wherein when the vehicle is driving in the second driving mode, it determines whether or not the road surface is uneven when the vehicle is driving using a first condition for determining whether or not the road is uneven in the first driving mode and a second condition for determining whether or not the road is uneven based on a signal from a knock sensor that detects engine knocking.

Description

Technical Field

[0001] The present disclosure relates to a road surface determination device.

Background Art

[0002] Conventionally, as this type of road surface determination device, there has been proposed one used in a hybrid vehicle equipped with an engine and a motor, which determines whether the road surface during traveling is a wavy road (for example, see Patent Document 1). In this device, it is determined whether the vehicle is traveling on a wavy road that causes resonance from the fluctuation width and fluctuation period of the rotational fluctuation of the motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described road surface determination device, vibration is indirectly detected from the fluctuation of the rotational fluctuation of the motor to determine whether the vehicle is traveling on a wavy road. Therefore, compared with a device that directly detects vibration, the detection accuracy of vibration is low, and the accuracy of determining a wavy road is low.

[0005] The main object of the road surface determination device of the present disclosure is to improve the accuracy of determining a wavy road.

Means for Solving the Problems

[0006] The road surface determination device of the present disclosure has adopted the following means to achieve the above main object.

[0007] The road surface determination device of the present disclosure A road surface determination device used in a hybrid vehicle that can switch between a first driving mode in which the vehicle is driven with the engine running and a second driving mode in which the vehicle is driven using power from the motor with the engine stopped, and which determines whether or not the road surface being driven is a wavy road, When driving in the second driving mode, the vehicle determines whether the road surface it is driving on is a wavy road using a first condition for determining a wavy road in the first driving mode and a second condition for determining a wavy road based on a signal from a knock sensor that detects engine knocking. This is the gist of it.

[0008] In the road surface determination device of this disclosure, when driving in the second driving mode, the device determines whether the road surface being driven on is a wavy road or not by using a first condition for determining a wavy road in the first driving mode and a second condition for determining a wavy road based on a signal from a knock sensor that detects engine knocking. When driving in the second driving mode, the engine is stopped, so the engine vibration caused by unevenness in the road surface can be directly detected by using the knock sensor. Therefore, by determining whether the road surface being driven on is a wavy road or not using the first condition for determining a wavy road in the first driving mode and the second condition for determining a wavy road based on a signal from the knock sensor, the accuracy of the wavy road determination can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] This diagram shows a schematic configuration of a hybrid vehicle equipped with a road surface determination device according to an embodiment of the disclosure. [Figure 2] This flowchart shows an example of a decision routine executed by HVECU. [Figure 3] This is an explanatory diagram showing an example of the time variation of a knock signal. [Modes for carrying out the invention]

[0010] Embodiments of this disclosure will be described with reference to the drawings. Figure 1 is a schematic diagram showing the configuration of a hybrid vehicle equipped with a road surface determination device according to an embodiment of this disclosure. As shown in Figure 1, the hybrid vehicle 20 of the embodiment includes an engine 22, a planetary gear 30, motors MG1 and MG2, inverters 41 and 42, a battery 50, and a hybrid electronic control unit (hereinafter referred to as HVECU) 70. Here, the road surface determination device is the HVECU 70.

[0011] Engine 22 is configured as an internal combustion engine that outputs power using gasoline, diesel fuel, or the like. This engine 22 is operated and controlled by HVECU 70.

[0012] The planetary gear 30 is configured as a single-pinion type planetary gear mechanism. The rotor of the motor MG1 is connected to the sun gear of the planetary gear 30. The drive shaft 36, which is connected to the drive wheels 39a and 39b via a differential gear 38, is connected to the ring gear of the planetary gear 30. The crankshaft 23 of the engine 22 is connected to the carrier of the planetary gear 30 via a damper 28.

[0013] Motor MG1 is configured, for example, as a synchronous generator-motor, and as described above, its rotor is connected to the sun gear of the planetary gear 30. Motor MG2 is configured, for example, as a synchronous generator-motor, and its rotor is connected to the drive shaft 36. Inverters 41 and 42 are used to drive motors MG1 and MG2 and are connected to the battery 50 via the power line 54. Motors MG1 and MG2 are rotationally driven by the HVECU 70, which controls the switching of multiple switching elements (not shown) of inverters 41 and 42.

[0014] The battery 50 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and as described above, is connected to inverters 41 and 42 via power lines 54. This battery 50 is managed by HVECU 70.

[0015] Although not shown in the diagram, the HVECU70 is configured as a microprocessor centered around a CPU. In addition to the CPU, it includes ROM for storing processing programs, RAM for temporarily storing data, input / output ports, and communication ports. The HVECU70 receives the following inputs via its input ports: crank angle θcr from a crank position sensor (not shown) that detects the rotational position of the crankshaft 23 of the engine 22; knock signal Ks from a knock sensor 22k that detects vibrations of the engine 22; rotational positions θm1 and θm2 of the rotors of motors MG1 and MG2 from rotational position sensors 40a and 40b that detect the rotational positions of the rotors of motors MG1 and MG2; the voltage Vb of the battery 50 from a voltage sensor (not shown) attached between the terminals of the battery 50; the current Ib of the battery 50 from a current sensor (not shown) attached to the output terminal of the battery 50; the temperature Tb of the battery 50 from a temperature sensor (not shown) attached to the battery 50; the ignition signal from the ignition switch 80; the accelerator opening Acc from an accelerator pedal position sensor 84 that detects the amount the accelerator pedal 83 is depressed; and the vehicle speed V from a vehicle speed sensor 88. The HVECU70 outputs various control signals for operating the engine 22 and switching control signals to multiple switching elements (not shown) of inverters 41 and 42 via its output ports. The HVECU70 calculates the rotational speed of the crankshaft 23, i.e., the rotational speed Ne of the engine 22, based on the crank angle θcr from the crank position sensor; calculates the rotational speeds Nm1 and Nm2 of motors MG1 and MG2 based on the rotor rotation positions θm1 and θm2 from the rotational position sensors 40a and 40b; and calculates the state of charge (SOC) of battery 50 based on the integrated value of the current Ib from the current sensor. The state of charge (SOC) is the ratio of the amount of power that can be discharged from battery 50 to the total capacity of battery 50.

[0016] In the hybrid vehicle 20 of this embodiment, the vehicle operates by switching between a hybrid driving mode (HV driving mode, first driving mode) in which the engine 22 is operated and an electric driving mode (EV driving mode, second driving mode) in which the engine 22 is stopped.

[0017] Next, the operation of the hybrid vehicle 20 of the embodiment configured in this way, in particular, the operation when determining whether or not the road surface is a wavy road while driving, will be described. Figure 2 is a flowchart showing an example of a determination routine executed by the HVECU. This routine is repeatedly executed at predetermined intervals (for example, every few milliseconds) while the hybrid vehicle 20 is driving in EV driving mode or HV driving mode.

[0018] When this routine is executed, the CPU of the HVECU70 determines whether or not the hybrid vehicle 20 is driving in EV driving mode (S100). If the hybrid vehicle 20 is not driving in EV driving mode, that is, if it is driving in HV driving mode, it determines whether or not the rotational speed condition (first condition) based on the rotational speed Nm2 of the motor MG2 is met (S110). When driving on a wavy road, the drive wheels 39a, 39b and driven wheels bounce due to the unevenness of the road surface, causing rotational fluctuations in the motor MG2, so it is possible to determine whether or not the vehicle is driving on a wavy road from the fluctuation in the rotational speed Nm2 of the motor MG2. The CPU of the HVECU70 takes into account the fluctuation in rotational speed Nm2 when driving on a wavy road, applies signal processing using a bandpass filter that passes a signal of a predetermined bandwidth BWref through the rotational speed Nm2, and determines that the rotational speed condition is met when the magnitude of the signal after processing exceeds a predetermined value Nm2ref for a predetermined time tref or longer. The predetermined bandwidth BWref is a bandwidth determined in advance through experiments, analyses, and machine learning, representing the frequency range of fluctuations in rotational speed Nm2 when the road surface is corrugated. The predetermined value Nm2ref is a value determined in advance through experiments, analyses, and machine learning, representing the lower limit of the signal magnitude after signal processing by a bandpass filter on rotational speed Nm2 when the road surface is corrugated. The predetermined time tref is a time determined in advance through experiments, analyses, and machine learning, representing the lower limit of the duration of vibration when the road surface is corrugated.

[0019] The HVECU70's CPU, if the rotational speed condition is not met in S110, determines that the road surface is not wavy (S140) and terminates this routine. If the rotational speed condition is met in S110, the HVECU70's CPU determines that the road surface is wavy (S150) and terminates this routine. Through these determinations, the HVECU70's CPU can properly determine whether or not the road surface is wavy when driving in HV driving mode.

[0020] When the CPU of HVECU 70 determines that the hybrid vehicle 20 is running in the EV driving mode at S100, it determines whether the rotational speed condition is satisfied in the same process as S110 (S120). When the rotational speed condition is satisfied, the CPU of HVECU 70 determines that the road surface is a wavy road (S150) and ends this routine.

[0021] When the rotational speed condition is not satisfied at S120, the CPU of HVECU 70 then determines whether a knock sensor condition (second condition) based on the knock signal Ks from the knock sensor 22k is satisfied (S130). FIG. 3 is an explanatory diagram showing an example of the temporal change of the knock signal. When driving on a wavy road, vibrations occur in the engine 22 due to the driving wheels 39a, 39b and the driven wheels bouncing due to the unevenness of the road surface. In the EV driving mode where the engine 22 is stopped, the knock signal Ks from the knock sensor 22k shown by the thin solid line in FIG. 3 shows fluctuations reflecting the unevenness of the road surface. Therefore, the CPU of HVECU 70 can determine whether the vehicle is driving on a wavy road from the knock signal Ks. The CPU of HVECU 70 performs signal processing using a band-pass filter that passes a signal in a predetermined band BWksref for the knock signal Ks, taking into account the fluctuations of the knock signal Ks when driving on a wavy road. When the time during which the magnitude of the signal after the processing (thick solid line in FIG. 3) exceeds a predetermined value Ksref continues for a predetermined time tksref or more, it is determined that the knock sensor condition is satisfied. The predetermined band BWksref is a band determined in advance by experiments, analysis, machine learning, etc. as the frequency range of the fluctuations of the knock signal Ks when the road surface is a wavy road. The predetermined value Ksref is a value determined in advance by experiments, analysis, machine learning, etc. as the lower limit value of the magnitude of the signal after performing signal processing on the knock signal Ks when the road surface is a wavy road using a band-pass filter. The predetermined time tksref is a time determined in advance by experiments, analysis, machine learning, etc. as the lower limit value of the duration of the vibration when the road surface is a wavy road.

[0022] When the CPU of the HVECU 70 determines that the knock sensor condition is not satisfied at S130, it determines that the road surface is not a wavy road (S140) and ends this routine. When the CPU of the HVECU 70 determines that the knock sensor condition is satisfied at S130, it determines that the road surface is a wavy road (S150) and ends this routine. In this way, when the CPU of the HVECU 70 is running in the EV driving mode, by determining whether the road surface is a wavy road using the rotation speed condition and the knock sensor condition, it is possible to improve the accuracy of the determination of the wavy road. Also, since it is determined whether the road surface is a wavy road using the knock sensor 22k attached to the normal engine 22, an increase in the number of parts of the hybrid vehicle 20 can be suppressed.

[0023] According to the hybrid vehicle 20 of the present embodiment described above, when running in the EV driving mode, based on the rotation speed condition for determining a wavy road in the HV driving mode and the knock sensor condition for determining a wavy road from the knock signal Ks from the knock sensor 22k that detects knocking of the engine 22, by determining whether the road surface during running is a wavy road, it is possible to improve the accuracy of the determination of the wavy road.

[0024] In the above-described embodiment, when the CPU of the HVECU 70 is running in the EV driving mode, when the rotation speed condition is satisfied at S120, or when the knock sensor condition is satisfied at S130, it may determine that the road surface is a wavy road, and when the rotation speed condition is not satisfied at S120 and the knock sensor condition is not satisfied at S130, it may determine that the road surface is not a wavy road. However, when the rotation speed condition is satisfied at S120 and the knock sensor condition is satisfied at S130, the CPU of the HVECU 70 may determine that the road surface is a wavy road, and when the rotation speed condition is not satisfied at S120 or the knock sensor condition is not satisfied at S130, it may determine that the road surface is not a wavy road.

[0025] In the embodiment described above, the CPU of the HVECU70 performs signal processing using a bandpass filter that allows a signal of a predetermined bandwidth BWref to pass through with respect to the rotational speed Nm2, and determines that the rotational speed condition is met when the magnitude of the signal after processing exceeds a predetermined value Nm2ref for a predetermined time tref or longer. However, the CPU of the HVECU70 may also determine that the rotational speed condition is met without waiting for a predetermined time tref to elapse when the magnitude of the signal after processing using a bandpass filter that allows a signal of a predetermined bandwidth BWref to pass through with respect to the rotational speed Nm2 exceeds a predetermined value Nm2ref.

[0026] In the embodiment described above, the CPU of the HVECU70 performs signal processing on the knock signal Ks using a bandpass filter that allows a signal of a predetermined bandwidth BWksref to pass through, and determines that the knock sensor condition is met when the magnitude of the signal after processing exceeds a predetermined value Ksref for a predetermined time tksref or longer. However, the CPU of the HVECU70 may also determine that the knock signal condition is met without waiting for a predetermined time tksref to elapse when the magnitude of the signal after processing exceeds a predetermined value Ksref, after performing signal processing on the knock signal Ks using a bandpass filter that allows a signal of a predetermined bandwidth BWksref to pass through.

[0027] In the embodiments described above, the disclosure is applied to a hybrid vehicle 20 comprising an engine 22, a planetary gear 30, and motors MG1 and MG2. However, the disclosure may be applied to any hybrid vehicle 20 comprising an engine and a motor, for example, to a hybrid vehicle in which the engine and motor are connected via a clutch.

[0028] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be explained. In the embodiment, HVECU70 corresponds to the "road surface determination device".

[0029] Furthermore, the correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem is merely an example to specifically explain the form in which the embodiment implements the invention described in the section on means for solving the problem, and does not limit the elements of the invention described in the section on means for solving the problem. In other words, the interpretation of the invention described in the section on means for solving the problem should be based on the description in that section, and the embodiment is merely one specific example of the invention described in the section on means for solving the problem.

[0030] The above describes the forms for implementing this disclosure using embodiments, but this disclosure is not limited in any way to these embodiments, and can of course be implemented in various forms without departing from the gist of this disclosure. [Industrial applicability]

[0031] This disclosure can be used in industries such as the manufacturing of road surface inspection devices. [Explanation of Symbols]

[0032] 20 Hybrid vehicles, 70 Hybrid electronic control units (HVECU).

Claims

[Claim 1] A road surface determination device used in a hybrid vehicle that can switch between a first driving mode in which the vehicle is driven with the engine running and a second driving mode in which the vehicle is driven using power from the motor with the engine stopped, and which determines whether or not the road surface being driven is a wavy road, When driving in the second driving mode, the vehicle determines whether the road surface it is driving on is a wavy road using a first condition for determining a wavy road in the first driving mode and a second condition for determining a wavy road based on a signal from a knock sensor that detects engine knocking. Road surface determination device.

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