Vehicle control system

Abstract

To avoid or suppress discomfort caused by change in NV characteristics or ride comfort resulting from change in mount characteristics.SOLUTION: A vehicle control device is such that an engine is supported to a vehicle body by a mount where negative pressure lower than atmospheric pressure is operated from a prescribed negative pressure source and thereby spring properties are changed to rigidity characteristics or flexible characteristics, a pipeline making the negative pressure source and the mount communicate with each other is opened or closed by a valve system, and output control for changing an output torque and a rotation frequency of the engine is executed without an operation by a driver. A controller controlling the valve mechanism is structured so that an engine operation point determined by at least either one of the output torque and the rotation frequency turns to a prescribed switching operation point and thereby the open / close state of the valve mechanism is switched (step S5) when the output control is executed (step S1), and also the prescribed switching operation point can be set by a vehicle occupant (step S2).SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a control device in a vehicle equipped with a heavy object that generates vibrations such as an engine, and particularly to a device for controlling a mount that supports the heavy object.

Background Art

[0002] An example of an engine mount whose spring characteristics or vibration damping characteristics can be changed is described in Patent Document 1. The engine mount described in Patent Document 1 is of a liquid-filled type and has a first liquid chamber filled with liquid, a second liquid chamber through which liquid flows in and out of the first liquid chamber as the volume of the first liquid chamber increases or decreases due to engine vibration, and an orifice provided between the liquid chambers, and the opening area of ​​the orifice is configured to increase or decrease with the intake negative pressure of the engine. More specifically, the orifice is composed of two openings, and a diaphragm is pressed against one of the openings by a return spring to close the opening. In addition, a switching valve that can be electrically switched is provided in the middle of the pipeline that applies the engine's intake negative pressure to the diaphragm. In the idling speed range, the switching valve is operated by a signal from the control device to apply the engine's intake negative pressure to the diaphragm. In this way, the diaphragm is moved away from the opening by the engine's intake negative pressure, resisting the elastic force of the return spring, and the opening opens. As a result, the overall opening area of ​​the orifice increases, and the resistance to liquid flow decreases, which reduces the effective spring constant of the engine mount, resulting in a so-called soft characteristic. In contrast, at engine speeds higher than the idling speed range, the engine's intake negative pressure is blocked from the diaphragm, and the diaphragm is pressed against one of the openings by the return spring, closing it. As a result, the overall opening area of ​​the orifice decreases, the resistance to liquid flow increases, the effective spring constant of the engine mount increases, resulting in a so-called stiff characteristic. In other words, the engine mount described in Patent Document 1 is configured so that its characteristics change from hard to soft (rigid to flexible) at an engine speed of approximately idling speed. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2003-049892 [Overview of the project] [Problems that the invention aims to solve]

[0004] The engine mount described in Patent Document 1 above is a vibration-damping member sometimes referred to as a negative pressure switching mount. Because the opening and closing of an orifice-functioning opening is performed using the engine's intake negative pressure, the elastic properties or effective spring constant of the mount can be automatically changed. This intake negative pressure increases (resulting in a larger vacuum pressure) when the driver presses the accelerator pedal and increases the engine speed, and conversely decreases (resulting in a smaller vacuum pressure) when the driver releases the accelerator pedal and decreases the engine speed. In other words, the characteristics of the mount switch according to the driver's acceleration and deceleration operations, and the driver's intention to drive the vehicle and the characteristics of the mount or their changes are in agreement or related.

[0005] On the other hand, engine output or rotational speed may change without the driver's intent. One example of this is when the vehicle follows a vehicle in front using ACC (Adaptive Cruise Control). In this type of control, the engine output is controlled to maintain the vehicle speed set manually by the driver. In addition, if another vehicle is detected ahead by radar or the like, the engine output is controlled to maintain a predetermined distance from the vehicle in front. Furthermore, when no other vehicle is detected ahead, the engine output is controlled to increase the speed to the set vehicle speed. Therefore, when this type of control is being performed, the engine output or rotational speed of the vehicle changes depending on the distance to the vehicle in front, the speed of the vehicle in front, etc., without the driver's intent. In a vehicle equipped with the mount described in Patent Document 1 above, if the engine output changes due to the relationship with other vehicles, etc., without the driver's intent, not only will the engine output and rotational speed change, but the characteristics of the engine mount will also change without the driver's intent or operation. Therefore, changes in the characteristics of the mounts due to unintended changes in engine output or rotational speed, as well as resulting vehicle vibrations, noise, and changes in ride comfort, may cause discomfort.

[0006] This invention was made against the background described above, and aims to provide a vehicle control device that can avoid or suppress changes in noise and vibration characteristics (NV characteristics) and ride comfort caused by changes in the characteristics of the mounts supporting the engine and other components, which can result in an unnatural feeling. [Means for solving the problem]

[0007] To achieve the above objective, this invention relates to a vehicle control device in which an engine that generates vibrations when operating is supported to the vehicle body by a mount whose spring characteristics change to rigid or flexible characteristics when a negative pressure lower than atmospheric pressure is applied from a predetermined negative pressure source, a pipe connecting the negative pressure source and the mount is opened and closed by a valve mechanism, and output control is performed to change the output torque and rotational speed of the engine without the operation of the driver, the device having a controller that controls the valve mechanism, the controller being configured such that when the output control is performed the operating point of the engine, which is determined by at least one of the output torque and rotational speed, becomes a predetermined switching operating point, thereby switching the open / closed state of the valve mechanism, and the predetermined switching operating point can be set by the occupant of the vehicle. [Effects of the Invention]

[0008] According to this invention, the spring characteristics of the mount supporting the engine to the vehicle body change between rigid and flexible depending on the negative pressure applied by the operation of the valve mechanism. For example, when the negative pressure is switched to a rigid characteristic, the engine is firmly fixed to the vehicle body, resulting in a smoother ride. Conversely, when the negative pressure is switched to a flexible characteristic, engine vibrations are less likely to be transmitted to the vehicle body, thus suppressing vibrations and noise in the vehicle body and improving the so-called NVH (Noise, Vibration, and Harshness) characteristics. Such changes occur when the vehicle is running with the engine output controlled independently of the driver's operation, as the engine's operating point reaches a predetermined switching point. In this invention, the driver can appropriately set the predetermined switching point that causes the valve mechanism to switch. Therefore, even when the engine output is controlled without driver intervention and the driver's intentions regarding driving are not reflected in the engine control, the driver's intentions can be reflected in the spring characteristics of the mounts supporting the engine to the vehicle body. As a result, changes in the vehicle's behavior due to changes in the engine's operating point (operating point) become understood by the driver, thus avoiding or suppressing any feeling of discomfort the driver may experience. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram illustrating an embodiment of the present invention. [Figure 2] This is a diagram illustrating an example of a map with pre-set switching points. [Figure 3] This is a block diagram showing the functional configuration of the controller. [Figure 4] This is a flowchart illustrating an example of the control performed in an embodiment of this invention. [Modes for carrying out the invention]

[0010] Next, embodiments of this invention will be described with reference to the attached drawings. It should be noted that the embodiments described below are merely examples of how this invention can be implemented and do not limit the invention.

[0011] Figure 1 schematically shows a mount 1 in an embodiment of this invention. Mount 1 is configured to support a heavy member that generates vibrations due to the operation of the engine 2 or the like, against the vehicle body (not shown). The vehicle is equipped with an engine 2 as a driving force source and is capable of not only accelerating and decelerating in response to the operation of the driver (occupant, not shown), but also of driving by accelerating and decelerating in accordance with other vehicles in front (vehicles ahead). One example of such following driving is driving using the ACC control described above, in which the driver operates the start and end of the control, and the driver sets the distance between vehicles when following and the vehicle speed when no vehicle ahead is detected.

[0012] The mount 1 shown in Figure 1 is a type of mount that encloses a fluid 3 such as oil, and may have a configuration similar to that described in the aforementioned Patent Document 1. In the example shown in Figure 1, the inside of the housing 4 is configured such that the internal volume increases or decreases while the fluid 3 is sealed in a liquid-tight state. For example, an elastic support part 5 made of an elastic material such as rubber is integrated into the upper side of Figure 1, and the upper end of the housing 4 is sealed by this elastic support part 5. A connecting part 6 made of a metal material passes through the center of this elastic support part 5 and is integrated with it, and a bolt 7 is attached to this connecting part 6, and the engine 2 is attached by this bolt 7.

[0013] A diaphragm 8 is provided in the lower part of the housing 4 shown in Figure 1. This diaphragm 8 and the elastic support part 5 described above form an oil chamber 9 inside the housing 4, in which the internal volume can be changed. The oil chamber 9 is divided into two by a partition plate 10, and the upper oil chamber 9a and the lower oil chamber 9b shown in Figure 1 are connected by two openings (orifices) 11a and 11b formed in the partition plate 10. In other words, these openings 11a and 11b provide flow resistance to the fluid 3 flowing between the respective oil chambers 9a and 9b.

[0014] The diaphragm 8 is pushed toward the partition plate 10 by a spring 13 provided between it and the bottom plate 12 that closes the bottom of the housing 4. On the upper surface of the diaphragm 8 (the surface facing the partition plate 10), a plug (closing member) 14 is provided at a position opposite the first opening 11a, which is pressed against the first opening 11a to close the first opening 11a. Therefore, when the first opening 11a is closed by the plug 14, the fluid 3 flows only through the second opening 11b, so the fluid resistance to the fluid 3 increases, and the spring characteristics of the mount 1 become rigid characteristics with a large effective spring constant. Conversely, when the first opening 11a is open, the fluid resistance to the fluid 3 decreases, and the spring characteristics of the mount 1 become flexible characteristics with a small effective spring constant.

[0015] The space between the diaphragm 8 and the bottom plate 12 is designated as a negative pressure chamber 15 and is connected to a negative pressure source 17 by a predetermined conduit 17. The negative pressure source 17 is a part that generates negative pressure lower than atmospheric pressure, and one example of this is the downstream part of the throttle valve 18 that restricts and adjusts the intake air volume in the engine 2. A valve mechanism 19 is also provided in the middle of the conduit 17. The valve mechanism 19 is a mechanism that switches between a state in which the negative pressure chamber 15 is connected to the negative pressure source 17 (hereinafter referred to as the OFF state) and a state in which it is connected to the atmosphere (hereinafter referred to as the ON state) by electrically controlled operation (opening and closing operation). The elastic force of the diaphragm 8 and the spring 13 is set so that when negative pressure acts on the negative pressure chamber 15, the diaphragm 8 bends downward in Figure 1, causing the plug 14 to move away from the first opening 11a and open the first opening 11a.

[0016] A controller 20 is provided to control the valve mechanism 19. The controller 20 is an electronic control device mainly consisting of a microcomputer, which performs calculations using input data and pre-stored data, and is configured to output a control command signal to switch the valve mechanism 19 from the OFF state to the ON state and a control command signal to switch it from the ON state to the OFF state as a result of the calculations. Input data includes an ACC / ON signal indicating that ACC control is being performed, vehicle speed, engine speed, engine output torque, and whether or not there is a failure in the control equipment. Pre-stored data includes, for example, the operating point (output torque or speed: switching operating point) of the engine 2 that switches the valve mechanism 19. Multiple switching operating points are prepared in advance in the form of a map or similar, corresponding to the operating point (operating point) of the engine 2, and are stored so that the driver can select and set one as appropriate when ACC control is performed. Figure 2 schematically shows a map of switching operating points, and in this example, it is configured to select and set one of the operating points indicated by lines labeled A, B, and C, with the switching operating points moving towards the high output side in the order of A, B, and C. Furthermore, hysteresis is set between the operating point for switching from the OFF state to the ON state (solid line in Figure 2) and the operating point for switching from the ON state to the OFF state (dashed line). Therefore, a selection switch 21 is connected to the controller 20.

[0017] The controller 20 is configured to perform a control to change the characteristics of the mount 1 to be rigid or flexible when the engine 2 is controlled and the vehicle is running without driver intervention, by performing calculations according to a pre-stored program. The functional configuration for this control is shown in a block diagram in Figure 3. The control to switch the spring characteristics of the mount 1 is performed when the engine 2 is controlled and the vehicle is running without driver intervention, so the controller 20 has an ACC control determination unit 20a that determines such a driving state, for example, ACC control. If the determination is successful, the switching of the spring characteristics is performed based on the switching operation point selected by the driver, so a switching operation point acquisition unit 20b is provided that reads the switching operation point selected by the selection switch 21. Furthermore, the switching of the spring characteristics of the mount 1 is performed when the vehicle is running and the driving state satisfies predetermined conditions. These predetermined conditions may be that the vehicle speed when following a vehicle in front is within a range of above a predetermined vehicle speed and below another predetermined vehicle speed. The controller 20 includes a predetermined condition determination unit 20c that determines whether such predetermined conditions are met. Furthermore, the controller 20 is provided with a switchability determination unit 20d that determines whether it is possible to switch the spring characteristics of the mount 1, such as when there is no failure in the control equipment. The controller 20 also includes a control command output unit 20e that outputs a control command signal to switch the spring characteristics of the mount 1, that is, a command signal to switch the valve mechanism 19 between the ON state and the OFF state, when the operating point determined by the input engine output torque and engine speed reaches a switching operating point stored as a map. The command signal to switch from the ON state to the OFF state is output at one of the switching operating points shown by the dashed line in Figure 2, and the command signal to switch from the OFF state to the ON state is output at one of the switching operating points shown by the solid line in Figure 2.

[0018] An example of the control executed by the controller 20 having the above-described functional configuration will be described with reference to the flowchart shown in FIG. 4. The routine shown in FIG. 4 is executed, for example, when the vehicle is running. First, it is acquired that the output control of the engine 2 is being executed regardless of the driver's operation (e.g., accelerator operation), for example, that the ACC control is set (step S1). Next, the switching operation point selected by the selection switch 21 described above is read (step S2). Further, it is determined whether or not the above-described predetermined conditions are satisfied, such as the vehicle speed being within a predetermined range while following the preceding vehicle (step S3).

[0019] If the determination result in step S3 is "No" because the predetermined conditions are not satisfied, the determination of the establishment of the predetermined conditions is continued. On the other hand, if the determination result in step S3 is "Yes", it is determined whether or not it is possible to switch the spring characteristics of the mount 1, that is, whether or not it is possible to switch the valve mechanism 19 between ON and OFF (step S4). If the determination result in this step S4 is "No", the immediately preceding control state is continued. On the contrary, if the determination result in step S4 is "Yes", the switching of the spring characteristics of the mount 1 is executed (step S5), and the routine shown in FIG. 4 is temporarily terminated.

[0020] Specifically, the switching of the spring characteristics is executed by outputting a command signal to switch the valve mechanism 19 from the OFF state to the ON state when the engine speed or the operating point of the engine 2 changes in the increasing direction and reaches the switching operation point selected by the driver. That is, by communicating the negative pressure chamber 15 in the mount 1 to the atmosphere to make it atmospheric pressure, the first opening 11a of the orifice is closed by the plug 14. By doing so, the flow resistance to the fluid 3 increases, so that the spring constant becomes a large rigid characteristic. As a result, the engine 2 is firmly fixed to the vehicle body, which is advantageous for improving the riding comfort during high-speed running at a high engine speed.

[0021] On the contrary, when the rotational speed or the operating point of the engine 2 changes in the decreasing direction and reaches the switching operation point selected by the driver, a command signal for switching the valve mechanism 19 from the ON state to the OFF state is output. That is, by communicating the negative pressure chamber 15 in the mount 1 with the negative pressure source 17 to make it negative pressure, the plug 14 is separated from the first opening 11a of the orifice to open the first opening 11a. By doing so, the flow resistance for the fluid 3 becomes smaller, so that the spring characteristic becomes a soft characteristic with a smaller substantial spring constant. As a result, since the mount 1 is easily elastically deformed, the vibration of the engine 2 is attenuated by the mount 1. Therefore, vibration and noise when the engine rotational speed decreases are less likely to be transmitted to the vehicle body, which is advantageous for improving the NV characteristics of the vehicle body.

[0022] The switching of the spring characteristic of the mount 1 due to the operating point of the engine 2 reaching the switching operation point occurs automatically when the output torque or the rotational speed of the engine 2 changes without the driver performing an operation to change the output of the engine 2. Since the switching operation point is set by the driver operating the selection switch 21, the change in the spring characteristic of the mount 1 and the accompanying change in the behavior of the vehicle, etc. match the driver's prediction or intention. Therefore, according to the embodiment of the present invention that performs the above-described control, even if the rotational speed or the output torque of the engine 2 changes without the driver's operation and the spring characteristic of the mount 1 switches accordingly, the driver's intention is reflected in such a switch and the accompanying change in the behavior of the vehicle, so that it is possible to avoid or suppress causing a sense of discomfort to the driver.

[0023] Note that the present invention is not limited to the above-described embodiment, and can be appropriately modified and implemented within the scope of the object of the present invention. For example, the configuration of the mount 1 and the configuration of the valve mechanism 19 may be other than the configuration shown in FIG. 1 as long as they have the functions described in the above-described embodiment. Also, the map defining the switching operation point is not limited to the form shown in FIG. 2, and may be an appropriate configuration as needed.

Explanation of Reference Numerals

[0024] 1 Mount 2 engines 3 fluid 4 cabinets 5. Elastic support section 6 Connecting part 7 volts 8 diaphragms 9,9a,9b Oil room 10 partition plates 11a,11b opening 12 Bottom plate 13 Spring 14 plugs 15. Negative pressure chamber 16 Conduit 17. Negative pressure source 18 Throttle valve 19 Valve mechanism 20 controllers 20a ACC control determination unit 20b Switching operation point acquisition unit 20c Predetermined condition judgment section 20d Switchable determination unit 20e Control command output section 21 Selector switch

Claims

[Claim 1] A vehicle control device comprising an engine that generates vibrations when in operation, supported by a mount whose spring characteristics change between rigid and flexible characteristics when a negative pressure lower than atmospheric pressure is applied from a predetermined negative pressure source, a valve mechanism opens and closes a pipeline connecting the negative pressure source and the mount, and further performs output control that changes the output torque and rotational speed of the engine without driver operation, It has a controller that controls the valve mechanism, The aforementioned controller, When the output control described above is being performed, the operating point of the engine, which is determined by at least one of the output torque and rotational speed, becomes a predetermined switching operating point, thereby switching the open / closed state of the valve mechanism, and The predetermined switching point is configured to be set by the occupant of the vehicle. A vehicle control device characterized by the following features.

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