Vehicle control device

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 capable of changing spring characteristics or vibration damping characteristics 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 in which the volume of the first liquid chamber increases and decreases due to the vibration of the engine, and liquid flows into and out of the first liquid chamber, and an orifice provided between these liquid chambers. The opening area of the orifice is configured to increase and decrease by 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. Also, a switching valve that can be electrically switched is provided in the middle of a pipeline for applying the intake negative pressure of the engine to the diaphragm. In the idling speed range, the switching valve is operated by a signal from the control device to apply the intake negative pressure of the engine to the diaphragm. By doing so, the diaphragm moves away from the above-mentioned opening against the elastic force of the return spring due to the intake negative pressure of the engine, and the opening opens. As a result, the overall opening area of the orifice increases, and the resistance to the flow of liquid decreases, so that the substantial spring constant of the engine mount decreases and becomes a so-called soft characteristic. On the other hand, when the rotational speed is higher than the idling speed range, the intake negative pressure of the engine is blocked from the diaphragm, and the diaphragm is pressed against the above-mentioned one opening by the return spring to close it. As a result, the overall opening area of the orifice decreases, and the resistance to the flow of liquid increases, so that the substantial spring constant of the engine mount increases and becomes a so-called hard characteristic. That is, the engine mount described in Patent Document 1 is configured such that the characteristics change from hard to soft (rigid to flexible) with the rotational speed around the idling speed as a boundary.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The engine mount described in the above-mentioned Patent Document 1 is a vibration damping member that may be referred to as a negative pressure switching mount. Since the opening and closing of the opening that functions as an orifice is performed using the intake negative pressure of the engine, the elastic characteristics or the substantial spring constant of the mount can be automatically changed. The intake negative pressure increases (becomes a large vacuum pressure) when, for example, the driver depresses the accelerator pedal to increase the engine speed, and conversely, it decreases (becomes a small vacuum pressure) when the driver releases the accelerator pedal to decrease the engine speed. That is, according to the acceleration and deceleration operations by the driver, the characteristics of the mount are switched, and the driving intention of the vehicle by the driver and the characteristics of the mount or their changes are consistent or related.

[0005] On the other hand, the output or rotational speed of the engine may change without being based on the driver's intention. An example of this is when the host vehicle travels following a preceding vehicle by ACC control (Adaptive Cruise Control). In this type of control, the output of the engine is controlled to maintain the vehicle speed set by the driver's manual operation. In addition, when a preceding other vehicle is detected by a radar or the like, the output of the engine is controlled to maintain a preset inter-vehicle distance from the preceding vehicle. Further, when no other vehicle is detected ahead, the output of the engine is controlled to increase the speed up to the set vehicle speed. Therefore, when this type of control is being executed, the output or rotational speed of the engine of the host vehicle changes depending on the distance from the preceding vehicle, the vehicle speed of the preceding vehicle, etc., without depending on the operation intended by the driver. In a vehicle equipped with the mount described in Patent Document 1 above, when the engine output changes depending on the relationship with other vehicles without depending on the driver's intention, not only the change in the output and rotational speed of the engine, but also the change in the characteristics of the engine mount occurs without depending on the driver's intention or operation. Therefore, the change in the characteristics of the mount accompanying the unintended change in the engine output or rotational speed, the resulting vibration and noise of the vehicle, and further the change in the riding comfort may cause discomfort.

[0006] The present invention has been made against the background of the above circumstances, and an object thereof is to provide a vehicle control device capable of avoiding or suppressing the discomfort caused by the change in the characteristics of noise and vibration (NV characteristics) and riding comfort resulting from the change in the characteristics of the mount that supports the engine and the like.

Means for Solving the Problem

[0007] In order to achieve the above object, the present invention provides a vehicle control device in which an engine that generates vibration by operating is supported on a vehicle body by a mount whose spring characteristics change from rigid characteristics to flexible characteristics when negative pressure lower than atmospheric pressure acts from a predetermined negative pressure source, a pipe that communicates the negative pressure source and the mount is opened and closed by a valve mechanism, and output control for changing the output torque and rotational speed of the engine is executed without depending on the operation of a driver. The vehicle control device has a controller that controls the valve mechanism. When the output control is being executed, the controller switches the open / closed state of the valve mechanism when an operating point of the engine determined by at least one of the output torque and the rotational speed reaches a predetermined switching operating point, and the predetermined switching operating point is configured to be settable by a passenger of the vehicle.

Advantages of the Invention

[0008] According to the present invention, the spring characteristics of the mount that supports the engine on the vehicle body change between rigid and flexible according to the operating state of the negative pressure caused by the operation of the valve mechanism. For example, when the operating state of the negative pressure is switched to be in the rigid characteristic state, the engine is firmly fixed to the vehicle body and the riding comfort is improved. On the other hand, when the operating state of the negative pressure is switched to be in the flexible characteristic state, the vibration of the engine is less likely to be transmitted to the vehicle body, so the vibration and noise of the vehicle body are suppressed and the so-called NV characteristics are improved. Such a change in the state where the vehicle is running while controlling the output of the engine without depending on the operation of the driver occurs when the operating point of the engine reaches a predetermined switching operating point. In the present invention, a predetermined switching operating point for switching the valve mechanism can be set appropriately by the driver. Therefore, even in a state where the output of the engine is controlled without the driver's operation and the driver's driving intention is not reflected in the engine control, the driver's intention can be reflected in the spring characteristics of the mount that supports the engine on the vehicle body. As a result, the change in the behavior of the vehicle accompanying the change in the operating point (operating point) of the engine becomes understandable to the driver, and it is possible to avoid or suppress the driver from feeling discomfort.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0010] Next, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the embodiments described below are merely examples of implementing the present invention and do not limit the present invention.

[0011] FIG. 1 schematically shows a mount 1 in an embodiment of the present invention. The mount 1 is configured to support a heavy member that generates vibration when an engine 2 or the like operates with respect to a vehicle body (not shown) of the vehicle. The vehicle is provided with an engine 2 as a driving force source and can not only accelerate and decelerate according to an operation by a driver (a passenger, not shown), but also perform acceleration and deceleration following a preceding vehicle (a vehicle in front). An example of such following driving is driving by the aforementioned ACC control, in which the driver performs operations for starting and ending the control, and also sets the inter-vehicle distance when following and the vehicle speed when the preceding vehicle is not detected.

[0012] The mount 1 shown in Fig. 1 is a mount in a form that encloses a fluid 3 such as oil, and may have a configuration similar to that described in Patent Document 1 mentioned above. In the example shown in Fig. 1, the interior of the housing 4 is configured such that the internal volume increases and decreases while enclosing the fluid 3 in a liquid-tight state. For example, on the upper side of Fig. 1, an elastic support portion 5 made of an elastic material such as rubber is integrated, and the upper end portion of the housing 4 is sealed by this elastic support portion 5. A connecting portion 6 made of a metal material penetrates and is integrated into the central portion of this elastic support portion 5, a bolt 7 is attached to this connecting portion 6, and the engine 2 is attached by this bolt 7.

[0013] A diaphragm 8 is provided in the lower portion of the housing 4 in Fig. 1, and an oil chamber 9 with a variable internal volume is formed inside the housing 4 by this diaphragm 8 and the above-described elastic support portion 5. The oil chamber 9 is partitioned into two by a partition plate 10, and the upper oil chamber 9a and the lower oil chamber 9b in Fig. 1 communicate with each other through two openings (orifices) 11a and 11b formed in the partition plate 10. That is, flow resistance is imparted to the fluid 3 flowing between the respective oil chambers 9a and 9b by these openings 11a and 11b.

[0014] The diaphragm 8 is pushed toward the partition plate 10 by a spring 13 provided between the diaphragm 8 and a bottom plate 12 that closes the bottom of the housing 4. A plug (closing member) 14 that presses against the first opening 11a and closes the first opening 11a is provided at a position on the upper surface of the diaphragm 8 (the surface facing the partition plate 10) that faces 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 flow resistance to the fluid 3 increases and the spring characteristics of the mount 1 become a rigid characteristic with a large effective spring constant. On the contrary, when the first opening 11a is open, the flow resistance to the fluid 3 decreases and the spring characteristics of the mount 1 are configured to become a flexible characteristic with a small effective spring constant.

[0015] The space between the diaphragm 8 and the bottom plate 12 is defined as a negative pressure chamber 15, which is communicated with a negative pressure source 17 through a predetermined pipeline 17. The negative pressure source 17 is a part that generates a negative pressure lower than the atmospheric pressure. An example thereof is a part on the downstream side of a throttle valve 18 that adjusts by restricting the intake air amount in the engine 2. Also, a valve mechanism 19 is provided in the middle of the pipeline 17. The valve mechanism 19 is electrically controlled to operate (open and close), thereby switching between a state in which the negative pressure chamber 15 is communicated with the negative pressure source 17 (hereinafter, temporarily referred to as the OFF state) and a state in which it is communicated with the atmosphere (hereinafter, temporarily referred to as the ON state). Then, the elastic forces of the diaphragm 8 and the spring 13 are set such that when a negative pressure acts on the negative pressure chamber 15, the diaphragm 8 deflects downward in FIG. 1 and the plug 14 moves away from the first opening 11a to open the first opening 11a.

[0016] A controller 20 for controlling the valve mechanism 19 is provided. The controller 20 is an electronic control device mainly composed of a microcomputer, which performs calculations using the input data, pre-stored data, etc. As a result of the calculations, a control command signal for switching the above valve mechanism 19 from the OFF state to the ON state and a control command signal for switching from the ON state to the OFF state are output. The input data includes an ACC / ON signal indicating that ACC control is being executed, vehicle speed, engine speed, engine output torque, presence or absence of a failure in the control device, etc. In addition, the pre-stored data is, for example, the operating point (output torque or speed: switching operation point) of the engine 2 for switching the above valve mechanism 19. A plurality of these switching operation points are prepared and stored in advance in the form of a map or the like corresponding to the operating point (operating point) of the engine 2, and are, for example, appropriately selected and set by the driver during the execution of ACC control. FIG. 2 schematically shows a map of the switching operation points. In the example shown here, any one of the operation points indicated by the lines A, B, and C is selected and set, and the switching operation points become the high-output side in the order of A, B, and C. A hysteresis is set between the operation point for switching from the OFF state to the ON state (solid line in FIG. 2) and the operation point for switching from the ON state to the OFF state (broken line). Therefore, a selection switch 21 is connected to the controller 20.

[0017] When the engine 2 is controlled to run without the driver's operation, the controller 20 is configured to execute control for flexibly changing the characteristics of the mount 1 by performing calculations according to a program stored in advance. The functional configuration for that control is shown in a block diagram in FIG. 3. Since the control for switching the spring characteristics of the mount 1 is executed when the engine 2 is controlled to run without the driver's operation, the controller 20 has an ACC control determination unit 20a that determines such a running state, for example, the determination of ACC control. Since the switching of the spring characteristics when the determination is established is performed based on the switching operation point selected by the driver, a switching operation point acquisition unit 20b that reads the switching operation point selected by the selection switch 21 is provided. Further, the switching of the spring characteristics of the mount 1 is executed when the vehicle is running and the running state satisfies a predetermined condition. The predetermined condition may be that the vehicle speed in the state of following the vehicle ahead is within a range of not less than a predetermined vehicle speed and not more than another predetermined vehicle speed. The controller 20 includes a predetermined condition determination unit 20c that determines the establishment of such a predetermined condition. Further, a switchable determination unit 20d that determines that it is possible to execute the switching of the spring characteristics of the mount 1, such as no failure occurring in the control device, is provided in the controller 20. Then, when the operating point determined by the input engine output torque and engine speed reaches the switching operation point stored as a map, the controller 20 outputs a control command signal for switching the spring characteristics of the mount 1, that is, a command signal for switching the valve mechanism 19 between the ON state and the OFF state, and is provided with a control command output unit 20e. The command signal for switching from the ON state to the OFF state is output at any of the switching operation points indicated by the broken line in FIG. 2, and the command signal for switching from the OFF state to the ON state is output at any of the switching operation points indicated by the solid line in FIG. 2.

[0018] An example of the control executed by the controller 20 having the above 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 (for example, accelerator operation), for example, that the ACC control is set (step S1). Next, the switching operation point selected by the above-described selection switch 21 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 for switching the valve mechanism 19 from the OFF state to the ON state when the rotational 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 with the atmosphere to make it atmospheric pressure, the first opening 11a of the orifices is closed by the plug 14. By doing so, the flow resistance to the fluid 3 increases, so that the spring constant becomes large and the spring becomes rigid. 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 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 a 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 to the fluid 3 becomes smaller, so that the spring characteristic becomes a soft characteristic with a smaller substantial spring constant. As a result, the mount 1 is more likely to elastically deform, and the vibration of the engine 2 is attenuated by the mount 1. Therefore, vibration and noise when the engine 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, changes such as the switching of the spring characteristic of the mount 1 and the behavior of the vehicle associated therewith will match or be as intended by the driver. 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 change in the behavior of the vehicle associated therewith, so that it is possible to avoid or suppress causing 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 engine 3 fluid 4 housing 5 elastic support part 6 connecting part 7 bolt 8 diaphragm 9, 9a, 9b oil chamber 10 partition plate 11a, 11b opening 12 bottom plate 13 spring 14 plug 15 negative pressure chamber 16 pipeline 17 negative pressure source 18 throttle valve 19 valve mechanism 20 controller 20a ACC control determination part 20b switching operation point acquisition part 20c predetermined condition determination part 20d switchable determination part 20e control command output part 21 selection switch

Claims

【Claim 1】 An engine that generates vibration by operating is supported on a vehicle body by a mount whose spring characteristics change to rigid characteristics or soft characteristics when negative pressure lower than atmospheric pressure acts from a predetermined negative pressure source, and a pipe that communicates the negative pressure source and the mount is opened and closed by a valve mechanism, and further, an output control that changes the output torque and rotational speed of the engine without depending on the operation of the driver is executed. A control device for a vehicle, comprising: a controller that controls the valve mechanism; the controller: when the output control is being executed, switches the opening / closing state of the valve mechanism when an operating point of the engine determined by at least one of the output torque and the rotational speed reaches a predetermined switching operating point, and the predetermined switching operating point is configured to be set by a passenger of the vehicle. A control device for a vehicle, characterized by the above.

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