Control device of vehicle

Abstract

To provide a control device of a vehicle which can appropriately reduce vibrations and shocks generated during the engine startup.SOLUTION: A control device of a vehicle includes: an engine mount which can suppress vibrations in an engine and change stiffness by changing at least one of a spring constant and a damping coefficient; and a suspension which can change stiffness by changing at least one of the spring constant and damping coefficient, and reduces vibrations transmitted to a vehicle body. When starting an engine, when a vibration acceleration level of the vehicle body acceleration in a high-frequency range is equal to or greater than a first threshold α1, the stiffness of the engine mount is reduced (Step S5). When a vibration acceleration level of the vehicle body acceleration in the high-frequency range is equal to or greater than the first threshold α1 and the vibration acceleration level of the vehicle body acceleration in a low-frequency range is equal to or greater than a second threshold α2(α2>α1), the stiffness of the suspension is reduced (Step S7).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device for a vehicle equipped with an engine, and more particularly to a control device for a vehicle that reduces vibrations transmitted from the engine to a vehicle body and a passenger compartment. [Background technology]

[0002] Patent Document 1 describes a vehicle body vibration reduction device that is intended to block the transmission of vibration from the engine and also reduce vibration and noise in the vehicle cabin due to vibration input from the suspension, etc. The vehicle body vibration reduction device described in Patent Document 1 includes an active mount consisting of a rubber bush that receives the load of the engine, a mount case having two fluid chambers separated by the rubber bush, an orifice that communicates the two fluid chambers, a movable blocking member that variably blocks one of the two fluid chambers, and an actuator that drives the movable blocking member according to a control signal. The vehicle body vibration reduction device described in Patent Document 1 uses the above active mount as an engine mount, divides the engine speed into four ranges, and controls the active mount with control content (control mode) preset for each range. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-179325 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, in the vehicle body vibration reduction device described in Patent Document 1, the active mount is controlled with control contents corresponding to different frequency ranges of engine speed. For example, in the region where the engine speed is between 30 Hz and 60 Hz, the active mount is controlled to cancel vibrations, assuming vibrations transmitted from the suspension. It is said that this reduces medium- to high-speed booming noise. However, the vehicle body vibration reduction device described in Patent Document 1 may not be able to achieve a sufficient vibration reduction effect depending on the type of vibration it corresponds to. For example, among the vibrations transmitted from the engine to the vehicle body and the passenger compartment, vibrations in the low frequency range that occur when the engine starts have relatively large amplitudes and displacements. In addition, resonance may occur in such low frequency ranges. In contrast, the active mount in the vehicle body vibration reduction device described in Patent Document 1 is an engine mount based on a bush-type fluid mount, with a variable spring constant and damping coefficient, and exhibits a vibration reduction effect in response to vibrations in different frequency ranges generated by an engine fixed to the vehicle body. However, the above-mentioned active mounts are basically designed to reduce vibrations in different frequency ranges that occur during steady engine operation, and are not designed to deal with all excessive vibrations and shocks that occur temporarily or instantaneously. Therefore, there is a risk that they will not be able to fully reduce vibrations that have large amplitudes and displacements such as those that occur during engine startup.

[0005] This invention was devised with a focus on the technical challenges described above, and aims to provide a vehicle control device that can reduce all vibrations transmitted from the engine to the vehicle body and passenger compartment, and in particular, appropriately reduce the vibrations and shocks that occur when the engine is started. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a control device for a vehicle which is equipped with at least an engine as a power source, and which is provided with an engine mount which supports the engine between the engine and a vehicle body to suppress vibrations of the engine and is capable of changing at least one of a spring constant or a damping coefficient to change its rigidity, and a suspension which supports wheels on the vehicle body and is capable of changing at least one of a spring constant or a damping coefficient to change its rigidity, and which reduces vibrations transmitted to the vehicle body, the control device comprising: a detection unit which detects the driving state of the vehicle, the driving state of the engine, and the acceleration of the vehicle body; and a controller that controls the stiffness of the engine mount and the stiffness of the suspension, wherein when the engine is started, the controller performs frequency analysis (or frequency analysis) on the detected value of the acceleration, and reduces the stiffness of the engine mount when a vibration acceleration level of the acceleration in a relatively high frequency range is equal to or greater than a predetermined first threshold, and reduces the stiffness of the suspension when the vibration acceleration level of the acceleration in the high frequency range is equal to or greater than the first threshold and the vibration acceleration level of the acceleration in a low frequency range lower than the high frequency range is equal to or greater than a second threshold that is greater than the first threshold.

[0007] The controller in the present invention may be configured to perform the frequency analysis when the vehicle speed is equal to or lower than a predetermined value, the engine is idling, and warm-up of the engine is completed. Effect of the Invention

[0008] In the vehicle control device of the present invention, the engine mount and suspension, whose characteristics (spring constant and damping coefficient) can be changed, are controlled to reduce vibrations in the vehicle body (vehicle interior) in response to different vibrations in different frequency ranges generated by the engine. When the vehicle body has high-frequency vibrations, i.e., when the acceleration of the vehicle body is large, the rigidity of the engine mount is reduced to reduce the vibrations transmitted from the engine to the vehicle body. On the other hand, when the vehicle body has high-frequency vibrations (vehicle body acceleration), the rigidity of the suspension is reduced to reduce the vibrations transmitted from the engine to the vehicle body. For example, when the engine is started, the vibrations in the low-frequency range are large, and there are cases where a sufficient vibration reduction effect cannot be obtained by simply changing the rigidity of the engine mount. In contrast, in the vehicle control device of the present invention, when the vibrations in the low-frequency range are large, such as when the engine is started, the rigidity of the suspension is reduced, thereby allowing the engine vibrations to escape to the wheel side. Therefore, even when the vibrations and shocks are large when the engine is started, the vibrations of the vehicle body can be effectively reduced.

[0009] The detection of the vehicle body acceleration and the frequency analysis of the vehicle body acceleration are performed when the vehicle is stopped or traveling at an extremely low vehicle speed of almost 0, the engine has finished warming up, and the idling speed is stable. Therefore, the vehicle body acceleration can be detected with high accuracy under conditions suitable for measuring acceleration, and the frequency analysis of the acceleration can be performed appropriately.

[0010] Therefore, according to the vehicle control device of the present invention, it is possible to reduce general vibrations (vibrations and shocks across different frequency ranges) transmitted from the engine to the vehicle body and passenger compartment, and in particular, to appropriately reduce vibrations and shocks that occur when the engine is started. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a vehicle to be controlled by a vehicle control device of the present invention. [Diagram 2] FIG. 2 is a flowchart for explaining an example of control executed by the vehicle control device of the present invention. [Diagram 3] FIG. 3 is a diagram for explaining an example of the control shown in the flowchart of FIG. 2, and shows examples of frequency analysis results for the acceleration (vibration) of the vehicle body, as well as examples of a low frequency range, a high frequency range, a first threshold value, and a second threshold value. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the accompanying drawings. Note that the following embodiment is merely an example of a specific embodiment of the present invention, and is not intended to limit the present invention.

[0013] Fig. 1 shows an example of a drive system and a control system of a vehicle Ve to be controlled in an embodiment of the present invention. The vehicle Ve shown in Fig. 1 is equipped with an engine (ENG) 1 as a drive power source, and is configured to transmit the output torque of the engine 1 to drive wheels (wheels) 3 via a transaxle 2, a differential gear (not shown), etc. The vehicle Ve also includes an active mount 4 and an active suspension 5. The vehicle Ve also includes a detection unit 7 and a controller (ECU) 8 to reduce vibration of a vehicle body 6 or a passenger compartment (not shown) by controlling the active mount 4 and the active suspension 5, respectively.

[0014] The active mount 4 is an "engine mount" that supports the engine 1 between the engine 1 and the vehicle body 6 and suppresses vibration of the engine 1. The active mount 4 is configured to be able to change the characteristics as an "engine mount" by changing at least one of the spring constant and the damping coefficient of the active mount 4 itself. In the example shown in FIG. 1, the active mounts 4 are provided at three locations between the engine 1 and the vehicle body 6. The active mount 4 is a well-known type of "engine mount" that controls the characteristics as an "engine mount" by changing the area of ​​an orifice (not shown) provided between multiple fluid chambers, similar to the "active mount" described in, for example, the above-mentioned Patent Document 1. The specific configuration of such an "active mount" using an orifice is described in the specification of the above-mentioned Patent Document 1. Alternatively, the active mount 4 may be one that uses the electromagnetic force of an electromagnetic solenoid (not shown) to control the characteristics as an "engine mount". An example of such an "active mount" using an electromagnetic solenoid is described in, for example, the specification of JP-A-2006-264402.

[0015] The active suspension 5 is a "suspension device" that supports the wheels (the above-mentioned driving wheels (front wheels) 3 and the rear wheels 9 described later) on the vehicle body 6 and absorbs vibrations transmitted from the road surface to the wheels 3, 9. The active suspension 5 is configured to be able to change the characteristics as a "suspension device" by changing at least one of the spring constant and damping coefficient of the active suspension 5 itself. The active suspension 5 is a well-known type that controls the characteristics as a "suspension device" by changing the suspension stroke and damping force using, for example, a motor-driven electric actuator. Examples of "active suspensions" using such electric actuators are described, for example, in the specifications of JP 2005-90616 A and JP 2011-16475 A.

[0016] In the embodiment of the present invention, the vehicle Ve to be controlled may be a vehicle Ve equipped with an internal combustion engine such as the engine 1, and is not limited to a so-called engine vehicle equipped with only the engine 1 as a driving force source as shown in Fig. 1. For example, the vehicle may be a hybrid vehicle (not shown) using the engine 1 and a motor (not shown) as driving force sources. Alternatively, the vehicle may be a series type hybrid vehicle (not shown) equipped with the engine 1 as a power source for driving a generator (not shown), or an electric vehicle (not shown) so-called a range extender.

[0017] 1, the vehicle Ve to be controlled in the embodiment of the present invention may be a front-wheel drive vehicle in which drive torque is transmitted to front wheels (drive wheels) 3 and drive force is generated at the front wheels 3. Alternatively, the vehicle Ve may be a rear-wheel drive vehicle (not shown) in which drive torque is transmitted to rear wheels 9 via, for example, a propeller shaft (not shown) and drive force is generated at the rear wheels 9. Alternatively, the vehicle Ve may be a four-wheel drive vehicle (not shown) provided with a transfer mechanism (not shown) in which drive torque is transmitted to both the front wheels 3 and the rear wheels 9 and drive force is generated at both the front wheels 3 and the rear wheels 9.

[0018] The detection unit 7 is a device or apparatus for acquiring various data and information required for controlling the vehicle Ve, and includes, for example, a power supply unit, a microcomputer, a sensor, and an input / output interface. In particular, the detection unit 7 in the embodiment of the present invention detects the driving state of the vehicle Ve and the driving state of the engine 1, and detects various data for controlling the active mount 4 and the active suspension 5 described above. Specifically, the detection unit 7 has a vehicle body acceleration sensor 7a for detecting the acceleration of the vehicle body 6. In addition, the detection unit 7 has, for example, a vehicle speed sensor 7b for detecting the vehicle speed, an engine speed sensor 7c for detecting the speed of the engine 1, a water temperature sensor 7d for detecting the temperature of the cooling water of the engine 1, an oil temperature sensor 7e for detecting the temperature of the oil in the engine 1, and the like. The detection unit 7 may also have an engine acceleration sensor (not shown) for detecting the acceleration of the engine 1 body. The detection unit 7 is electrically connected to a controller 8 described later, and outputs, as detection data, electric signals and the like corresponding to the detection values ​​or calculated values ​​of the various sensors, devices, and the like described above to the controller 8.

[0019] The controller 8 is an electronic control device mainly composed of, for example, a microcomputer, and the controller 8 in the embodiment of the present invention controls the vehicle Ve, and in particular, controls the stiffness of the active mount 4 and the stiffness of the active suspension 5. The controller 8 receives various data detected or calculated by the detection unit 7. The controller 8 performs calculations using the input various data and pre-stored data, calculation formulas, and the like. The controller 8 then outputs the calculation results as a control command signal and controls the vehicle Ve as described above. Note that, although FIG. 1 shows an example in which one controller 8 is provided, multiple controllers 8 may be provided for each device or equipment to be controlled, or for each control content.

[0020] As described above, in a vehicle Ve equipped with the engine 1 as a power source, if vibrations generated by the engine 1 are transmitted to the vehicle body 6 and the driver and passengers of the vehicle Ve, it will affect the ride quality and comfort of the vehicle Ve. In particular, when starting the engine 1, the vibrations and shocks transmitted from the engine 1 to the vehicle body 6 become large, and the ride quality and comfort of the vehicle Ve decreases. In order to appropriately reduce such large vibrations and shocks when starting the engine 1, the controller 8 of the vehicle Ve in the embodiment of the present invention is configured to execute, for example, the control shown in the flowchart of FIG. 2 below.

[0021] 2 is executed when the vehicle Ve is stopped and the engine 1 is idling. Therefore, first, in step S1, it is determined whether the vehicle speed is 0 and the engine 1 is idling. In this case, the determination may include a state in which the vehicle Ve is almost stopped, and therefore, instead of determining whether the vehicle speed is 0, it may be determined whether the vehicle speed is equal to or lower than a predetermined vehicle speed (close to 0).

[0022] If the answer to step S1 is "No" because the vehicle speed is not 0 or the engine 1 is not idling, the routine shown in the flowchart of FIG. 2 is temporarily terminated without executing the control of the subsequent steps.

[0023] On the other hand, if the vehicle speed is 0 and the engine 1 is idling, so that "Yes" is determined in step S1, the process proceeds to step S2.

[0024] In step S2, it is determined whether the temperature of the cooling water of the engine 1 (engine water temperature) is within a predetermined temperature range. The predetermined temperature range in this case is determined in advance as a threshold value for determining whether the warm-up of the engine 1 is complete. If the engine water temperature is within the predetermined temperature range, it is determined that the warm-up of the engine 1 is complete and the idling operation of the engine 1 is stable.

[0025] If the engine water temperature is outside the predetermined temperature range and therefore the answer to step S2 is "No," it is determined that the idling operation of the engine 1 is unstable. Therefore, the routine shown in the flowchart of FIG. 2 is temporarily terminated without executing the control of the subsequent steps.

[0026] On the other hand, if the engine water temperature is within the predetermined temperature range and therefore "Yes" is determined in step S2, the process proceeds to step S3.

[0027] In step S3, the vibration of the vehicle body 6 is measured. Specifically, the acceleration of the vehicle body 6 (vehicle body acceleration) is detected. At the same time, a frequency analysis is performed on the detected value of the vehicle body acceleration. For example, the temporarily recorded detection value of the vehicle body acceleration sensor 7a for a predetermined time period from immediately before the start of the engine 1 is captured, and a frequency analysis is performed on the detection value.

[0028] Next, in step S4, it is determined whether or not the vehicle body vibration in the high frequency range is equal to or greater than a predetermined value. Specifically, it is determined from the result of the frequency analysis in step S3 above whether or not the vibration acceleration level of the vehicle body acceleration in the high frequency range is equal to or greater than a first threshold value α1.

[0029] As shown in FIG. 3, the vibration (vehicle body acceleration) of the vehicle body 6 has different typical or standard vibration modes between a relatively high frequency range between the frequency F1 and the frequency F2 and a low frequency range below the frequency F1, which is lower than the high frequency range. In the high frequency range, a relatively stable vibration occurs at a relatively small vibration acceleration level. In contrast, the low frequency range includes the vibration and shock generated at the start of the engine 1 as described above, and a relatively large vibration occurs temporarily or instantaneously at a relatively large vibration acceleration level. Therefore, in the embodiment of the present invention, the high frequency range and the low frequency range as described above are distinguished, and thresholds corresponding to each frequency range are set to determine the state of the vibration of the vehicle body 6. In this case, the first threshold value α1 is determined in advance as a threshold value for determining the vibration that requires a vibration reduction measure in the high frequency range. When the vibration acceleration level of the vehicle body acceleration in the high frequency range is equal to or higher than the first threshold value α1, it is determined that a vibration that affects the ride quality and comfort of the vehicle Ve occurs and that a vibration reduction measure is required for the vibration.

[0030] Therefore, if the vibration acceleration level of the vehicle body acceleration in the high frequency range is less than the first threshold value α1 and thus the result of the determination in step S4 is "No," it is determined that no particular measures to reduce vibration are required as described above. Therefore, the routine shown in the flowchart of FIG. 2 is temporarily terminated without executing the control of the subsequent steps.

[0031] On the other hand, if the vibration acceleration level of the vehicle body acceleration in the high frequency range is equal to or greater than the first threshold value α1, and therefore "Yes" is determined in step S4, the process proceeds to step S5.

[0032] In step S5, vibration reduction measures are implemented for vibrations of the vehicle body 6 in the high frequency range. Specifically, control is executed to reduce the rigidity of the active mount 4. For example, the spring constant of the active mount 4 is controlled to be smaller, thereby reducing the rigidity of the active mount 4. In conjunction with reducing the spring constant of the active mount 4, the damping coefficient of the active mount 4 may be changed so that the vibration of the active mount 4 is appropriately damped. By reducing the rigidity of the active mount 4, the vibration of the engine 1 is more easily absorbed by the active mount 4, and the vibration transmitted from the engine 1 to the vehicle body 6 is reduced.

[0033] Next, in step S6, it is determined whether or not the vehicle body vibration in the low frequency range is equal to or greater than a predetermined value. Specifically, it is determined from the result of the frequency analysis in step S3 above whether or not the vibration acceleration level of the vehicle body acceleration in the low frequency range is equal to or greater than a second threshold value α2.

[0034] As shown in FIG. 3, the vibration (vehicle body acceleration) of the vehicle body 6 has different typical or standard vibration modes between a relatively high frequency range between the frequency F1 and the frequency F2 and a low frequency range below the frequency F1, which is lower than the high frequency range. In the high frequency range, a relatively stable vibration occurs at a relatively small vibration acceleration level. In contrast, the low frequency range includes the vibration and shock generated at the start of the engine 1 as described above, and a relatively large vibration occurs temporarily or instantaneously at a relatively large vibration acceleration level. Therefore, in the embodiment of the present invention, the high frequency range and the low frequency range as described above are distinguished, and threshold values ​​corresponding to each frequency range are set to determine the state of the vibration of the vehicle body 6. In this case, the second threshold value α2 is a value larger than the first threshold value α1 described above, and is previously determined as a threshold value for determining the vibration that requires a vibration reduction measure in the low frequency range. When the vibration acceleration level of the vehicle body acceleration in the low frequency range is equal to or higher than the second threshold value α2, it is determined that a vibration that affects the ride quality and comfort of the vehicle Ve occurs and that a vibration reduction measure is required for the vibration.

[0035] Therefore, if the vibration acceleration level of the vehicle body acceleration in the low frequency range is less than the second threshold value α2 and thus the result of the determination in step S6 is "No," it is determined that no particular measures to reduce vibration are required as described above. Therefore, the routine shown in the flowchart of FIG. 2 is temporarily terminated without executing the control of the subsequent steps.

[0036] On the other hand, if the vibration acceleration level of the vehicle body acceleration in the low frequency range is equal to or greater than the second threshold value α2, and therefore "Yes" is determined in step S6, the process proceeds to step S7.

[0037] In step S7, a vibration reduction measure is implemented for vibrations of the vehicle body 6 in the low frequency range. Specifically, a control is executed to reduce the stiffness of the active suspension 5. For example, the spring constant of the active suspension 5 is controlled to be smaller, and the stiffness of the active suspension 5 is reduced. In conjunction with reducing the spring constant of the active suspension 5, the damping coefficient of the active suspension 5 may be changed so that the vibrations of the active suspension 5 are appropriately damped. By reducing the stiffness of the active suspension 5, the vibrations of the engine 1 are more easily absorbed by the active suspension 5, and the vibrations transmitted from the engine 1 to the vehicle body 6 are reduced.

[0038] As described above, when the engine 1 is started, vibrations in the low frequency range become large, and there are cases where a sufficient vibration reduction effect cannot be obtained by simply changing the rigidity of the active mount 4. In contrast, in the vehicle control device according to the embodiment of the present invention, when vibrations in the low frequency range become large, such as when the engine 1 is started, the rigidity of the active suspension 5 is reduced, thereby allowing the vibrations of the engine 1 to escape to the wheels 3, 9. Therefore, even when vibrations and shocks become large when the engine 1 is started, the vibrations of the vehicle body 6 can be effectively reduced.

[0039] As described above, when the control for reducing the stiffness of the active suspension 5 is executed in step S7, the routine shown in the flowchart of FIG. 2 is temporarily ended thereafter.

[0040] As described above, the vehicle control device in the embodiment of the present invention controls the active mounts 4 and active suspensions 5, whose characteristics (spring constants and damping coefficients) can be changed, thereby making it possible to reduce vibrations in the vehicle body 6 in response to vibrations in different frequency ranges generated by the engine 1. When the vibrations of the vehicle body 6 in the high frequency range, i.e., when the vehicle body acceleration is large, the rigidity of the active mounts 4 can be reduced to reduce the vibrations transmitted from the engine 1 to the vehicle body 6. On the other hand, when the vibrations of the vehicle body 6 in the low frequency range (vehicle body acceleration) are large, the rigidity of the active suspensions 5 can be reduced to reduce the vibrations transmitted from the engine 1 to the vehicle body 6.

[0041] Therefore, according to the vehicle control device of this embodiment of the present invention, it is possible to reduce general vibrations (i.e., vibrations and shocks across different frequency ranges) transmitted from the engine 1 to the vehicle body 6 and the passenger compartment, and in particular, to appropriately reduce vibrations and shocks that occur when the engine 1 is started. [Explanation of symbols]

[0042] 1 Engine (ENG) 2 Transaxle (TA) 3 Drive wheels (front wheels, wheels) 4 Active mount (engine mount) 5 Active suspension (suspension) 6. Body 7. Detection section 7a (Detection section) vehicle acceleration sensor 7b (Detection section) Vehicle speed sensor 7c (Detection section) Engine speed sensor 7d (Detection section) Water temperature sensor 7e Oil temperature sensor (detection section) 8 Controller (ECU) 9 Rear wheel (wheel) Vehicle

Claims

[Claim 1] A control device for a vehicle equipped with at least an engine as a power source, an engine mount supporting the engine between the engine and a vehicle body to suppress vibration of the engine and capable of changing rigidity by changing at least one of a spring constant or a damping coefficient, and a suspension supporting wheels on the vehicle body and capable of changing rigidity by changing at least one of a spring constant or a damping coefficient, the control device reducing vibration transmitted to the vehicle body, a detection unit that detects a driving state of the vehicle, a driving state of the engine, and an acceleration of the vehicle body; a controller that controls the vehicle and controls the stiffness of the engine mount and the stiffness of the suspension, The controller: When starting the engine, a frequency analysis is performed on the detected acceleration value; When a vibration acceleration level of the acceleration in a relatively high frequency range is equal to or higher than a predetermined first threshold value, a rigidity of the engine mount is reduced, and When a vibration acceleration level of the acceleration in the high frequency range is equal to or higher than the first threshold value and a vibration acceleration level of the acceleration in a low frequency range lower than the high frequency range is equal to or higher than a second threshold value that is higher than the first threshold value, the rigidity of the suspension is reduced. A vehicle control device comprising:

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