JP6604508B2 - Control method of automotive negative pressure pump - Google Patents

Description

  The present invention relates to a method for controlling a negative pressure pump for an automobile that controls a negative pressure pump configured to generate a negative pressure in a vacuum booster of the automobile.

  In general, in an automobile, it may be required to generate a negative pressure in a vacuum booster (or a brake booster) for assisting a brake. A diesel engine automobile, a gasoline direct injection engine automobile, a hybrid automobile, an idling engine may be required. In an automobile having an engine such as a stop automobile, the intake negative pressure generated in the intake path of the engine is used in order to generate such a negative pressure. However, in an automobile such as a hybrid automobile or an idling stop automobile that may stop the engine during operation, a situation occurs in which the intake negative pressure of the engine cannot be used. Therefore, a negative pressure pump is separately provided in order to obtain a negative pressure in the vacuum booster even in such a situation. Further, in an automobile having no engine such as an electric vehicle and a fuel cell vehicle, a negative pressure pump is provided in order to obtain a negative pressure in the vacuum booster.

  In the control of the negative pressure pump, the negative pressure pump is activated when the negative pressure in the vacuum booster falls below a predetermined activation threshold so that the negative pressure necessary to assist the brake can be obtained. In addition, the negative pressure pump is stopped when the negative pressure in the vacuum booster exceeds a predetermined stop threshold. As an example of such a negative pressure pump control method, it has been proposed to change the start threshold value and the stop threshold value in accordance with changes in atmospheric pressure. (For example, see Patent Document 1 and Patent Document 2.)

  As another example of the negative pressure pump control method, when the automobile is located in a lowland, control is performed so that the negative pressure, which is the difference between the atmospheric pressure and the absolute pressure in the vacuum booster, is maintained within a predetermined range. And a high altitude control pattern for controlling the absolute pressure in the vacuum booster within a predetermined range when the vehicle is located at a high altitude higher than the low altitude. It has been proposed to switch based on a switching threshold determined by atmospheric pressure. (For example, see Patent Document 3)

JP-A-9-58457 Special table 2014-522768 gazette Japanese Patent Laid-Open No. 9-177678

  However, when the negative pressure in the vacuum booster decreases due to a decrease in atmospheric pressure around the automobile, a change in the running speed of the automobile, or the like, there is a possibility that the negative pressure in the vacuum booster cannot be sufficiently secured. As a result of not being able to secure the necessary negative pressure in the vacuum booster in this way, there is a possibility that the negative pressure pump may continue to operate in one example of the negative pressure pump control method as described above, and as a result, the operation of the negative pressure pump Time may be longer. In this case, the life of the negative pressure pump is shortened and the negative pressure pump is liable to fail. Furthermore, it is not preferable that the operation noise of the negative pressure pump is frequently generated. That is, in an example regarding the control method of the negative pressure pump, there is a problem that the negative pressure pump cannot be accurately and efficiently controlled.

  Further, in another example relating to the negative pressure pump control method as described above, when the atmospheric pressure around the automobile changes in the vicinity of the switching threshold, the atmospheric pressure becomes lower than the switching threshold, so that the low altitude control pattern Switching to a high-pressure control pattern, and switching from a high-ground control pattern to a low-ground control pattern due to the atmospheric pressure being equal to or higher than the switching threshold, the negative pressure pump control becomes unstable. There is a fear. That is, in another example relating to the control method of the negative pressure pump, there is a problem that the negative pressure pump cannot be accurately and efficiently controlled.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for controlling a negative pressure pump for an automobile that can stably, accurately, and efficiently control the negative pressure pump. There is to do.

In order to solve the problem, a method for controlling a negative pressure pump for an automobile according to one aspect of the present invention includes a negative pressure for an automobile that controls a negative pressure pump configured to generate a negative pressure in a vacuum booster of the automobile. A control method for a pump, wherein the low pressure control pattern controls the negative pressure pump when the vehicle is located in a lowland, and the lowland control pattern when the vehicle is located at a high altitude higher than the lowland. In a method for controlling an automotive negative pressure pump, including a pattern switching step for switching between a high-altitude control pattern for controlling the negative pressure pump by a different method from the above, the negative pressure pump is controlled by the low-altitude and high-altitude control pattern A threshold changing step for changing the low pressure threshold for low ground and high ground, which are set as negative pressure values when starting or stopping, respectively, according to the traveling speed of the vehicle. Further comprising a said at pattern switching step, the first and the atmospheric pressure threshold is the value of the atmospheric pressure when switching from the lowland control pattern in the highland control pattern, the lowland control from the highland control pattern The second atmospheric pressure threshold value that is the atmospheric pressure value when switching to the pattern and is larger than the first atmospheric pressure threshold value is set to be different from the first atmospheric pressure threshold value. A negative low pressure threshold, a second low negative pressure threshold, and a third low negative pressure threshold, and the high negative pressure threshold can be changed to the first high negative pressure threshold, To the first highland negative pressure threshold, the first lowland negative pressure threshold is set equal to the first highland negative pressure threshold, and the second lowland negative pressure threshold is set to the second highland negative pressure threshold. A negative pressure threshold for use or more, and the third low-pressure negative pressure threshold is set to Greater than the negative pressure threshold for 2 highland to. In addition, the first lowland negative pressure threshold is the lowland negative pressure threshold when the traveling speed is in the lowland low speed region, and the second lowland negative pressure threshold is the traveling speed is the The low-pressure negative pressure threshold when the low-pressure medium-speed region is at a higher speed than the low-speed low-speed region, and the low-pressure negative pressure threshold set to be larger than the first low-ground negative pressure threshold. And the third lowland negative pressure threshold is the lowland negative pressure threshold when the traveling speed is in the lowland high speed region having a speed larger than the lowland medium speed region, and the second lowland negative pressure threshold is The low-pressure negative pressure threshold value set larger than the low-pressure negative pressure threshold value, and the first high-pressure negative pressure threshold value is the high-pressure negative pressure threshold value when the traveling speed is in the high-land low-speed region. And the second highland negative pressure threshold is greater than the highland low speed region. Preferred such is said negative pressure threshold for highlands when in the high speed region in the speed, and when is the larger set the highland negative pressure threshold than the first negative pressure threshold for high altitude. By such control, even when the atmospheric pressure changes in the vicinity of the first or second atmospheric pressure threshold, it is possible to prevent frequent switching between the lowland control pattern and the highland control pattern. As a result, the negative pressure pump can be controlled stably, accurately and efficiently. Further, by such control, a more accurate negative pressure can be obtained according to the altitude of the place where the automobile is located and the traveling speed of the automobile. In addition, since the negative pressure in the vacuum booster is changed according to the change in the running speed of the automobile, the negative pressure in the vacuum booster can be prevented from decreasing due to the change in the running speed, and the brake is assisted. Therefore, it is possible to prevent the negative pressure pump from continuing to operate due to the fact that the negative pressure required for the vacuum booster cannot be secured in the vacuum booster. As a result, the number of start-ups of the negative pressure pump can be reduced and the driving time of the negative pressure pump can be shortened, so that the life of the negative pressure pump is lengthened and the generation of operating noise from the negative pressure pump is reduced. In addition, the negative pressure pump can be controlled efficiently.

  According to the method for controlling a negative pressure pump for an automobile according to one aspect of the present invention, the negative pressure pump can be controlled stably, accurately, and efficiently.

It is a block diagram which shows roughly the control system which can implement the control method of the negative pressure pump which concerns on 1st Embodiment of this invention. It is a figure which shows the flowchart for demonstrating switching to the control pattern for low grounds and the control pattern for high grounds in 1st Embodiment of this invention. It is a figure which shows the flowchart for demonstrating the low-ground control pattern of 1st Embodiment of this invention. It is a figure which shows the graph regarding the relationship between the altitude, the absolute pressure in a vacuum booster, the negative pressure, and atmospheric pressure in the case of switching from the low-altitude control pattern to the high-altitude control pattern in the first embodiment of the present invention. It is a figure which shows the graph regarding the relationship between the altitude, the absolute pressure in a vacuum booster, the negative pressure, and atmospheric pressure in the case of switching from the high altitude control pattern to the low altitude control pattern in the first embodiment of the present invention. It is a figure which shows the flowchart for demonstrating the high altitude control pattern of 1st Embodiment of this invention. It is a figure which shows the graph regarding the relationship between the driving speed of a motor vehicle, the starting negative pressure threshold value, and a stop negative pressure threshold value in the low-ground control pattern of 2nd Embodiment of this invention. It is a figure which shows the flowchart for demonstrating the change of the starting and stop negative pressure threshold value in the low-ground control pattern of 2nd Embodiment of this invention. It is a figure which shows the graph regarding the relationship between the driving speed of a motor vehicle, the starting negative pressure threshold value, and a stop negative pressure threshold value in the high altitude control pattern of 2nd Embodiment of this invention. It is a figure which shows the flowchart for demonstrating the change of the starting and stop negative pressure threshold value in the high altitude control pattern of 2nd Embodiment of this invention.

[First Embodiment]
A method for controlling the negative pressure pump according to the first embodiment of the present invention will be described.

[About control system]
Initially, the control system which can implement the control method of the negative pressure pump concerning this embodiment is explained. In this embodiment, as an example, the control system is configured to be used in a hybrid vehicle having an engine. As shown in FIG. 1, the control system 1 includes a vacuum booster 2 configured to be able to assist braking of a vehicle and an engine 3 of the vehicle. The control system 1 is also configured to generate a negative pressure (hereinafter referred to as “booster negative pressure”), which is a difference between the atmospheric pressure around the automobile and the absolute pressure in the vacuum booster 2, in the vacuum booster 2. A negative pressure pump (hereinafter simply referred to as “negative pressure pump”) 4 is provided.

  The vacuum booster 2 is connected to the engine 3 by the first vacuum line 5 and is connected to the negative pressure pump 4 by the second vacuum line 6. The booster negative pressure is obtained using at least one of an intake negative pressure generated in the intake path of the engine 3 and a negative pressure generated by the negative pressure pump 4.

  Further, the control system 1 includes a hybrid system controller 7 configured to be able to control the distribution of driving force of the hybrid vehicle, and an ESP (Electronic Stability) configured to enable control for preventing the vehicle from skidding. Program) module 8 and an engine controller 9 configured to control the engine 3. The control system 1 is also configured to be able to measure a power source 10 used as a driving source of the negative pressure pump 4 and an absolute pressure in the vacuum booster 2 (hereinafter referred to as “booster absolute pressure”) and to the vacuum booster 2. An absolute pressure sensor 11 to be attached, an atmospheric pressure sensor 12 configured to be able to measure the atmospheric pressure, and a vehicle speed sensor 13 capable of measuring the traveling speed of the automobile are provided. In the present embodiment, as an example, the atmospheric pressure sensor 12 is attached to the engine 3.

  The power supply 10 is electrically connected to the negative pressure pump 4 by a first hard wire 14. The second hard wire 15 extending from the hybrid system controller 7 is electrically connected to the first hard wire 14 that connects the negative pressure pump 4 and the power source 10 via the relay unit 16. The hybrid system controller 7 can cooperate with the relay unit 16 to switch between a state in which the electrical connection between the negative pressure pump 4 and the power source 10 is maintained and a state in which the electrical connection is cut off. It is configured. Further, the absolute pressure sensor 11 is electrically connected to the ESP module 8 by the third hard wire 17. The atmospheric pressure sensor 12 is electrically connected to the engine controller 9 by a fourth hard wire 18. The vehicle speed sensor 13 is electrically connected to the ESP module 8 by a fifth hard wire 19.

  The hybrid system controller 7 and the ESP module 8 are connected to each other using the first data transfer unit 20 so as to enable data transfer between them. The ESP module 8 and the engine controller 9 are also connected to each other using the second data transfer unit 21 so as to enable data transfer between them. In addition, it is preferable that at least one of the first and second data transfer units 20 and 21 is a CAN (Controller Area Network).

  However, the control system of the present invention is not limited to this, and the control system is configured to be used for an engine-equipped vehicle other than a hybrid vehicle, for example, an idling stop vehicle or the like, or a vehicle without an engine, for example, It can be configured to be used for electric vehicles, fuel cell vehicles, and the like. In particular, when used in an automobile without an engine, the control system has a motor and a motor controller configured to control the motor instead of the engine and the engine controller. The pressure is controlled using the negative pressure generated by the negative pressure pump without using the intake negative pressure generated in the intake path of the engine as in an automobile having an engine. In addition to the hybrid system controller, such a control system is also a controller configured to be able to switch between a state in which the electrical connection of the negative pressure pump and the power source is maintained and a state in which the electrical connection is cut off. Can be provided separately. Furthermore, when the control system is used in an idling stop vehicle, the control system may have a controller configured to control a function that allows the engine to be stopped when idling, instead of the hybrid system controller.

[About control method]
Next, a method for controlling the negative pressure pump 4 according to the present embodiment will be described. In the control method of the negative pressure pump 4, the negative pressure pump 4 is controlled using the control system 1 described above. As shown in FIG. 2, in such a control method of the negative pressure pump 4, a low ground control pattern for controlling the negative pressure pump 4 when the automobile is located in a lowland, and the automobile is located at a high altitude higher than the lowland. In this case, it is possible to switch between the highland control pattern for controlling the negative pressure pump 4 by a method different from the lowland control pattern. In the lowland control pattern, the negative pressure pump 4 is controlled so as to maintain the booster negative pressure within a desired range, and in the highland control pattern, the negative pressure pump is maintained so as to maintain the booster absolute pressure within the desired range. 4 is controlled. Details of such low and high altitude control patterns will be described later.

[Switching between low and high altitude control patterns]
Switching between the lowland and highland control patterns will be described using the case where the vehicle is located in the lowland in the initial state. As shown in FIG. 2, the negative pressure pump 4 is controlled with a low-ground control pattern using the hybrid system controller 7 in a state where the automobile is initially positioned in the low-land (step STP1). The atmospheric pressure around the automobile is measured using the atmospheric pressure sensor 12, the atmospheric pressure measurement value A is sent from the atmospheric pressure sensor 12 to the engine controller 9, and the atmospheric pressure measurement value A is sent from the engine controller 9 to the ESP module 8. And the atmospheric pressure measurement value A is sent from the ESP module 8 to the hybrid system controller 7 as necessary. Whether at least one of the hybrid system controller 7 and the ESP module 8 is used, the measured value A of the atmospheric pressure is equal to or lower than the first atmospheric pressure threshold value b1 that serves as a reference when switching from the low altitude control pattern to the high altitude control pattern. Is determined (step STP2). The first atmospheric pressure threshold value b1 corresponds to the atmospheric pressure value A ′ when the altitude H at the location where the automobile is located is the first altitude threshold value i1. As an example to the last, the first atmospheric pressure threshold value b1 is preferably about 85 kPa.

  When the measured value A of the atmospheric pressure is larger than the first atmospheric pressure threshold value b1 (that is, when the altitude H is smaller than the first altitude threshold value i1) (NO), the negative pressure pump 4 is continuously changed to the low ground control pattern. (Step STP1). On the other hand, when the measured value A of the atmospheric pressure is equal to or lower than the first atmospheric pressure threshold value b1 (that is, when the altitude H is equal to or higher than the first altitude threshold value i1) (YES), the hybrid system controller 7 and the ESP module The control of the negative pressure pump 4 is switched from the low altitude control pattern to the high altitude control pattern using at least one of 8 and the negative pressure pump 4 is controlled by the high altitude control pattern (step STP3). Again, the atmospheric pressure around the vehicle is measured using the atmospheric pressure sensor 12, the measured value A of the atmospheric pressure is sent from the atmospheric pressure sensor 12 to the engine controller 9, and the measured value A of the atmospheric pressure is sent from the engine controller 9 to the ESP. The measured value A of atmospheric pressure is sent from the ESP module 8 to the hybrid system controller 7 as necessary. Whether at least one of the hybrid system controller 7 and the ESP module 8 is used, the measured value A of the atmospheric pressure is equal to or higher than a second atmospheric pressure threshold value b2 that is a reference for switching from the highland control pattern to the lowland control pattern. Is determined (step STP4). Note that the second atmospheric pressure threshold value b2 corresponds to the atmospheric pressure value A ′ when the altitude H where the vehicle is located is the second altitude threshold value i2. The second atmospheric pressure threshold value b2 is preferably larger than the first atmospheric pressure threshold value b1. As an example to the last, the second atmospheric pressure threshold b2 is preferably about 90 kPa. The difference between the first and second atmospheric pressure threshold values b1 and b2 is more preferably about 5 kPa.

  When the measured value A of the atmospheric pressure is smaller than the second atmospheric pressure threshold value b2 (that is, when the altitude H is larger than the second altitude threshold value i2) (NO), the negative pressure pump 4 is continuously set to the high altitude control pattern. (Step STP3). On the other hand, when the measured value A of the atmospheric pressure is equal to or higher than the second atmospheric pressure threshold value b2 (that is, when the altitude H is equal to or lower than the second altitude threshold value i2) (YES), the hybrid system controller 7 and the ESP module 8 The control of the negative pressure pump 4 is switched from the highland control pattern to the lowland control pattern using at least one of the above, and the negative pressure pump 4 is controlled by the lowland control pattern (step STP1).

[Low-level control pattern]
Details of the low-ground control pattern will be described using a case where the negative pressure pump 4 is stopped in the initial state. As shown in FIG. 3, first, the negative pressure pump 4 is in a stopped state (step STP11). The atmospheric pressure around the automobile is measured using the atmospheric pressure sensor 12, the atmospheric pressure measurement value A is sent from the atmospheric pressure sensor 12 to the engine controller 9, and the atmospheric pressure measurement value A is sent from the engine controller 9 to the ESP module 8. Send to. Further, the booster absolute pressure is measured using the absolute pressure sensor 11, and the measured value D of the booster absolute pressure is sent to the ESP module 8. Using the ESP module 8, a calculated value P of the booster negative pressure is calculated based on the measured value A of the atmospheric pressure and the measured value D of the booster absolute pressure. The calculated booster negative pressure value P is sent from the ESP module 8 to the hybrid system controller 7 as necessary. Using at least one of the hybrid system controller 7 and the ESP module 8, it is determined whether or not the booster negative pressure calculation value P is equal to or less than the startup negative pressure threshold q (step STP12).

  When the calculated value P of the booster negative pressure is larger than the starting negative pressure threshold q (NO), the negative pressure pump 4 is maintained in a stopped state (step STP11). On the other hand, when the calculated value P of the booster negative pressure is equal to or less than the starting negative pressure threshold q (YES), the negative pressure pump 4 and the power source 10 are electrically connected using the hybrid system controller 7 and the relay unit 16. As a result, the negative pressure pump 4 is started (step STP13). Again, the atmospheric pressure around the vehicle is measured using the atmospheric pressure sensor 12, the measured value A of the atmospheric pressure is sent from the atmospheric pressure sensor 12 to the engine controller 9, and the measured value A of the atmospheric pressure is sent from the engine controller 9 to the ESP. Send to module 8. Further, the booster absolute pressure is measured using the absolute pressure sensor 11, and the measured value D of the booster absolute pressure is sent to the ESP module 8. Using the ESP module 8, a calculated value P of the booster negative pressure is calculated based on the measured value A of the atmospheric pressure and the measured value D of the booster absolute pressure. The calculated booster negative pressure value P is sent from the ESP module 8 to the hybrid system controller 7 as necessary. Using at least one of the hybrid system controller 7 and the ESP module 8, it is determined whether or not the booster negative pressure calculation value P is equal to or greater than the stop negative pressure threshold r (step STP14).

  When the calculated value P of the booster negative pressure is smaller than the stop negative pressure threshold r (NO), the negative pressure pump 4 is maintained in the activated state (step STP13). On the other hand, when the calculated value P of the booster negative pressure is greater than or equal to the stop negative pressure threshold r (YES), the electrical connection between the negative pressure pump 4 and the power source 10 is disconnected using the hybrid system controller 7 and the relay unit 16. By doing so, the negative pressure pump 4 is stopped (step STP11).

  The stop negative pressure threshold r is larger than the start negative pressure threshold q. As an example only, the starting negative pressure threshold q is preferably about 47 kPa or more and about 67 kPa or less, and the stopping negative pressure threshold r is preferably about 60 kPa or more and about 74 kPa or less. The difference between the start and stop negative pressure threshold values q and r is more preferably about 7 kPa or more and about 13 kPa or less.

  In FIG. 4 relating to switching from the lowland control pattern to the highland control pattern, the horizontal axis indicates the altitude H (m) where the vehicle is located, and the left vertical axis indicates the booster absolute pressure value D ′. (Pa), and the vertical axis on the right represents the atmospheric pressure value A ′ (Pa). 4, the starting negative pressure threshold value q is a booster at the time of starting the negative pressure pump 4 indicated by the atmospheric pressure indicated by the alternate long and short dash line L and the solid line M1 in the region where the elevation H is smaller than the first elevation threshold value i1. The negative negative pressure threshold r, which is a difference from the absolute pressure, is indicated by the atmospheric pressure indicated by the one-dot chain line L and the two-dot chain line N1 in the region where the elevation H is smaller than the first elevation threshold i1. It is a difference from the booster absolute pressure when the negative pressure pump 4 is stopped.

  In FIG. 5 relating to switching from the high altitude control pattern to the low altitude control pattern, the horizontal axis indicates the altitude H (m) where the vehicle is located, and the left vertical axis indicates the booster absolute pressure value D ′ (Pa ) And the vertical axis on the right side represents the atmospheric pressure value A ′ (Pa). 5, the starting negative pressure threshold q is a booster at the time of starting the negative pressure pump 4 indicated by the atmospheric pressure indicated by the alternate long and short dash line L and the solid line M2 in the region where the altitude H is equal to or less than the second altitude threshold i2. The negative negative pressure threshold value r, which is a difference from the absolute pressure, is indicated by the atmospheric pressure indicated by the one-dot chain line L and the two-dot chain line N2 in the region where the altitude H is equal to or lower than the second altitude threshold value i2. It is a difference from the booster absolute pressure when the negative pressure pump 4 is stopped.

[About high altitude control pattern]
The details of the high altitude control pattern will be described using the case where the negative pressure pump 4 is stopped in the initial state. As shown in FIG. 6, initially, the negative pressure pump 4 is in a stopped state (step STP21). The absolute pressure sensor 11 is used to measure the booster absolute pressure, and the measured value D of the booster absolute pressure is sent to the ESP module 8. If necessary, the measured value D of the booster absolute pressure is sent from the ESP module 8 to the hybrid system controller 7. Using at least one of the hybrid system controller 7 and the ESP module 8, it is determined whether or not the measured value D of the booster absolute pressure is equal to or greater than the starting absolute pressure threshold e (step STP22).

  When the measured value D of the booster absolute pressure is smaller than the starting absolute pressure threshold e (NO), the negative pressure pump 4 is maintained in a stopped state (step STP21). On the other hand, when the calculated value P of the booster negative pressure is not less than the starting absolute pressure threshold e (YES), the negative pressure pump 4 and the power source 10 are electrically connected using the hybrid system controller 7 and the relay unit 16. As a result, the negative pressure pump 4 is started (step STP23). The absolute pressure sensor 11 is again used to measure the booster absolute pressure, and the measured value D of the booster absolute pressure is sent to the ESP module 8. If necessary, the measured value D of the booster absolute pressure is sent from the ESP module 8 to the hybrid system controller 7. Using at least one of the hybrid system controller 7 and the ESP module 8, it is determined whether or not the measured value D of the booster absolute pressure is equal to or less than the stop absolute pressure threshold f (step STP24).

  When the measured value D of the booster absolute pressure is greater than the stop absolute pressure threshold f (NO), the negative pressure pump 4 is maintained in the activated state (step STP23). On the other hand, when the measured value D of the booster absolute pressure is equal to or lower than the stop absolute pressure threshold f (YES), the electrical connection between the negative pressure pump 4 and the power source 10 is cut off using the hybrid system controller 7 and the relay unit 16. By doing so, the negative pressure pump 4 is stopped (step STP21).

  Note that the stop absolute pressure threshold f is larger than the start absolute pressure threshold e. As an example only, the starting absolute pressure threshold e is preferably about 40 kPa or more and about 53 kPa or less, and the stop absolute pressure threshold f is preferably about 37 kPa or more and about 40 kPa or less. The difference between the start and stop absolute pressure thresholds e and f is more preferably about 3 kPa or more and about 13 kPa or less.

  In FIG. 4 relating to switching from the low altitude control pattern to the high altitude control pattern, the starting absolute pressure threshold e is a negative pressure pump 4 indicated by a solid line M1 in an area where the altitude H is equal to or higher than the first altitude threshold i1. The booster absolute pressure at the time of start-up and the stop negative pressure threshold r is the absolute value of the booster at the stop of the negative pressure pump 4 indicated by the two-dot chain line N1 in the region where the altitude H is equal to or higher than the first altitude threshold i1. Pressure.

  In FIG. 5 relating to switching from the high altitude control pattern to the low altitude control pattern, the starting absolute pressure threshold e is a negative pressure pump indicated by a solid line M2 in a region where the altitude H is greater than the second altitude threshold i2. 4 is the absolute pressure of the booster at the time of starting, and the stop negative pressure threshold r is a region where the altitude H is larger than the second altitude threshold i2, and when the negative pressure pump 4 is stopped as indicated by a two-dot chain line N2. Booster absolute pressure.

  However, the low altitude and high altitude control patterns of the present invention are not limited to this, and the second atmospheric pressure threshold value b2 may be smaller than the first atmospheric pressure threshold value b1. In this case, the relationship between the altitude, the atmospheric pressure, the booster negative pressure and the booster absolute pressure when switching from the lowland control pattern to the highland control pattern can be as shown in FIG. The relationship between the altitude, the atmospheric pressure, the booster negative pressure, and the booster absolute pressure in the case of switching from the low-to-low control pattern can be as shown in FIG. If these relationships are illustrated in the drawing, the first atmospheric pressure threshold value b1 and the second atmospheric pressure threshold value b2 are interchanged.

[About action and effect]
As described above, according to the control method of the negative pressure pump 4 according to the present embodiment, even when the atmospheric pressure changes in the vicinity of the first or second atmospheric pressure thresholds b1 and b2, the lowland control pattern and the highland It can be prevented that the control pattern is frequently switched. As a result, the negative pressure pump 4 can be controlled stably, accurately and efficiently.

  Moreover, according to the control method of the negative pressure pump 4 according to the present embodiment, since the negative pressure pump 4 is controlled based on the booster absolute pressure, the automobile is particularly located at a high altitude where the atmospheric pressure is low. Even when the ambient atmospheric pressure decreases, it is possible to prevent the negative pressure pump 4 from continuing to operate due to the fact that the brake negative pressure necessary for assisting the brake cannot be secured. As a result, the number of start-ups of the negative pressure pump 4 can be reduced and the driving time of the negative pressure pump 4 can be shortened, so that the life of the negative pressure pump 4 is lengthened and the operating noise from the negative pressure pump 4 is reduced. The negative pressure pump 4 can be efficiently controlled so as to reduce the generation.

[Second Embodiment]
A method for controlling the negative pressure pump according to the second embodiment of the present invention will be described. The control system that enables the negative pressure pump control method according to the present embodiment to be implemented is the same as that of the first embodiment. In the negative pressure pump control method according to the present embodiment, the low-altitude control pattern and the high-altitude control pattern are switched as in the first embodiment.

  On the other hand, the low and high altitude control patterns of the present embodiment are different from the low altitude and high altitude control patterns of the first embodiment, both of which maintain the booster negative pressure within a desired range. Thus, the negative pressure pump 4 is controlled. That is, in both the lowland control pattern and the highland control pattern of the present embodiment, the booster negative pressure calculated value P is calculated and the booster negative pressure calculated value P is calculated as in the lowland control pattern of the first embodiment. Based on this, the start and stop of the negative pressure pump 4 are controlled so as to maintain the booster negative pressure within a desired range.

[Low-level control pattern]
Details of such a lowland control pattern will be described. In the lowland control pattern, the hybrid system controller 7 activates the negative pressure pump 4 when the calculated value P of the booster negative pressure is equal to or less than the activation negative pressure threshold s that can be changed according to the traveling speed of the vehicle, and The negative pressure pump 4 is stopped when the calculated value P of the booster negative pressure is equal to or greater than the stop negative pressure threshold t that can be changed according to the traveling speed of the automobile.

[Change of starting and stopping negative pressure threshold in low-level control pattern]
The change of the start and stop negative pressure thresholds s and t in the lowland control pattern will be described with reference to FIG. In FIG. 7, the horizontal axis represents the vehicle speed value W ′ (km / h), the left vertical axis represents the starting negative pressure threshold s (Pa), and the right vertical axis represents the stop negative pressure. The threshold value t (Pa) is shown. Further, in FIG. 7, the first to third starting negative pressure thresholds s1, s2, and s3 set according to the change in the traveling speed are indicated by X, and the first set according to the change in the traveling speed. The first to third stop negative pressure thresholds t1, t2, and t3 are indicated by circles. As shown in FIG. 7, the starting negative pressure threshold s includes a first starting negative pressure threshold s1 when the traveling speed is in the starting low speed region and a second starting when the traveling speed is in the middle starting speed region. The negative pressure threshold s2 is changed to the third starting negative pressure threshold s3 when the traveling speed is in the starting high speed region. The starting low speed region is set in a range where the traveling speed value W ′ is smaller than the first starting vehicle speed threshold x1, and in the middle speed region, the traveling speed value W ′ is equal to or more than the first starting vehicle speed threshold x1. At the same time, it is set in a range smaller than the second startup vehicle speed threshold value x2, and the high speed region is set in a range where the value W ′ of the traveling speed is equal to or greater than the second startup vehicle speed threshold value x2. The second startup vehicle speed threshold value x2 is larger than the first startup vehicle speed threshold value x1.

  The second startup negative pressure threshold s2 is set to be greater than the first startup negative pressure threshold s1, and the third startup negative pressure threshold s3 is set to be greater than the second startup stop negative pressure threshold s2. As an example only, the first starting negative pressure threshold s1 is preferably about 47 kPa, the second starting negative pressure threshold s2 is preferably about 60 kPa, and the third starting negative pressure threshold s3 is about 67 kPa. Preferably there is. The difference between the first and second starting negative pressure thresholds s1 and s2 is more preferably about 13 kPa, and the difference between the second and third starting negative pressure thresholds s2 and s3 is more preferably about 7 kPa. . The first startup vehicle speed threshold x1 is preferably about 20 km / h or more and about 30 km / h or less, and the second startup vehicle speed threshold x2 is preferably about 60 km / h or more and about 70 km / h or less.

  On the other hand, the stop negative pressure threshold t is a first stop negative pressure threshold t1 when the travel speed is in the stop low speed region, and a second stop negative pressure threshold t2 when the travel speed is in the middle stop speed region. And the third stop negative pressure threshold t3 when the traveling speed is in the stop high speed region. The stop low speed region is set in a range where the travel speed value W ′ is smaller than the first stop vehicle speed threshold y1, and in the medium speed region, the travel speed value W ′ is greater than or equal to the first stop vehicle speed threshold y1. At the same time, it is set in a range smaller than the second stop vehicle speed threshold value y2, and the high speed region is set in a range in which the travel speed value W ′ is not less than the second stop vehicle speed threshold value y2. The second stop vehicle speed threshold y2 is larger than the first stop vehicle speed threshold y1.

  The second stop negative pressure threshold t2 is set to be greater than the first stop negative pressure threshold t1, and the third stop negative pressure threshold t3 is set to be greater than the second stop negative pressure threshold t2. As an example only, the first stop negative pressure threshold t1 is preferably about 60 kPa, the second stop negative pressure threshold t2 is preferably about 67 kPa, and the third stop negative pressure threshold t3 is about 74 kPa. Preferably there is. The difference between the first and second stop negative pressure thresholds t1 and t2 is more preferably about 7 kPa, and the difference between the second and third stop negative pressure thresholds t2 and t3 is more preferably about 7 kPa. . The first stop vehicle speed threshold y1 is preferably about 10 km / h or more and about 20 km / h or less, and the second stop vehicle speed threshold y2 is preferably about 40 km / h or more and about 50 km / h or less.

  Here, the control flow for changing the start and stop negative pressure thresholds s and t will be described using the case where the vehicle is stopped in the initial state. As shown in FIG. 8, the automobile starts to travel (step STP31). The running speed is in the starting or stopping low speed region, and the starting or stopping negative pressure threshold value s, t becomes the first starting or stopping negative pressure threshold value s1, t1 (step STP32). The hybrid system controller 7 estimates the measured value W of the traveling speed based on the current value, voltage value, etc. of an inverter (not shown) provided therein, or measures the traveling speed using the vehicle speed sensor 13. The travel speed measurement value W is sent to the ESP module 8, and the travel speed measurement value W is sent from the ESP module 8 to the hybrid system controller 7 as necessary. Using at least one of the hybrid system controller 7 and the ESP module 8, it is determined whether or not the measured value W of the traveling speed is equal to or greater than the first start or stop vehicle speed threshold value x1, y1 (step STP33).

  When the measured value W of the traveling speed is smaller than the first start or stop vehicle speed threshold value x1 or y1 (NO), the travel speed is in the start or stop low speed region, and the start or stop negative pressure threshold value s or t is set to the first start or stop negative pressure threshold value s or t. The starting or stopping negative pressure threshold values s1, t1 are maintained (step STP32). On the other hand, when the measured value W of the travel speed is equal to or higher than the first start or stop vehicle speed threshold value x1, y1 (YES), the travel speed is in the start or stop middle speed region, and the start or stop negative pressure threshold value s, t is changed from the first start or stop negative pressure threshold value s1, t1 to the second start or stop negative pressure threshold value s2, t2 (step STP34). Again, the hybrid system controller 7 estimates the measured value W of the traveling speed based on the current value, voltage value, etc. of an inverter (not shown) provided therein, or uses the vehicle speed sensor 13 to determine the traveling speed. Then, the measured value W of the traveling speed is sent to the ESP module 8, and the measured value W of the traveling speed is sent from the ESP module 8 to the hybrid system controller 7 as necessary. Using at least one of the hybrid system controller 7 and the ESP module 8, it is determined whether or not the measured value W of the traveling speed is equal to or greater than the first start or stop vehicle speed threshold value x1, y1 (step STP35).

  When the measured value W of the travel speed is smaller than the first start or stop vehicle speed threshold value x1, y1 (NO), the travel speed is in the start or stop low speed region, and the start or stop negative pressure threshold value s, t is set to the second The starting or stopping negative pressure threshold value s2, t2 is changed to the first starting or stopping negative pressure threshold value s1, t1 (step STP32). On the other hand, when the measured value W of the traveling speed is greater than or equal to the first start or stop vehicle speed threshold value x1, y1 (YES), the measured value of the traveling speed is measured using at least one of the hybrid system controller 7 and the ESP module 8. It is determined whether W is greater than or equal to the second start or stop vehicle speed threshold value x2, y2 (step STP36).

  When the measured value W of the travel speed is smaller than the second start or stop vehicle speed threshold values x2 and y2 (NO), the travel speed is in the start or stop middle speed range, and the start or stop negative pressure threshold values s and t are set to the second The start or stop negative pressure thresholds s2 and t2 are maintained (step STP34). On the other hand, when the measured value W of the travel speed is equal to or greater than the second start or stop vehicle speed threshold value x2, y2 (YES), the travel speed is in the start or stop high speed region, and the start or stop negative pressure threshold value s, t Is changed from the second starting or stopping negative pressure threshold value s2, t2 to the third starting or stopping negative pressure threshold value s3, t3 (step STP37). Further, using at least one of the hybrid system controller 7 and the ESP module 8, it is determined whether or not the measured value W of the traveling speed is equal to or greater than the second start or stop vehicle speed threshold value x2, y2 (step STP38).

  When the measured value W of the travel speed is smaller than the second start or stop vehicle speed threshold value x2 or y2 (NO), the travel speed is in the start or stop middle speed range, and the start or stop negative pressure threshold values s and t are set to the third The starting or stopping negative pressure threshold value s3, t3 is changed to the second starting or stopping negative pressure threshold value s2, t2 (step STP34). On the other hand, when the measured value W of the travel speed is equal to or greater than the second start or stop vehicle speed threshold value x2, y2 (YES), the travel speed is in the start or stop high speed region, and the start or stop negative pressure threshold value s, t Is maintained at the third start or stop negative pressure threshold s3, t3 (step STP37).

  However, the control flow for changing the starting and stopping negative pressure thresholds s and t in the present invention is not limited to this, and the following steps may be performed when the traveling speed is in the starting or stopping middle speed region. Using at least one of the hybrid system controller 7 and the ESP module 8, it is determined whether or not the measured value W of the traveling speed is equal to or greater than the second start or stop vehicle speed threshold value x2, y2. When the measured value W of the travel speed is equal to or greater than the second start or stop vehicle speed threshold x2, y2 (YES), the travel speed is in the start or stop high speed region, and the start or stop negative pressure thresholds s and t are set to the second The starting or stopping negative pressure threshold value s2, t2 is changed to the third starting or stopping negative pressure threshold value s3, t3. On the other hand, when the measured value W of the traveling speed is smaller than the second start or stop vehicle speed threshold value x2, y2 (NO), the measured value of the traveling speed is measured using at least one of the hybrid system controller 7 and the ESP module 8. It is determined whether W is greater than or equal to the first start or stop vehicle speed threshold value x1, y1.

  When the measured value W of the travel speed is smaller than the first start or stop vehicle speed threshold value x1, y1 (NO), the travel speed is in the start or stop low speed region, and the start or stop negative pressure threshold value s, t is set to the second The starting or stopping negative pressure threshold value s2, t2 is changed to the first starting or stopping negative pressure threshold value s1, t1. On the other hand, when the measured value W of the travel speed is equal to or higher than the first start or stop vehicle speed threshold value x1, y1 (YES), the travel speed is in the start or stop high speed region, and the start or stop negative pressure threshold value s, t Is changed from the second start or stop negative pressure threshold value s2, t2 to the third start or stop negative pressure threshold value s3, t3.

[About high altitude control pattern]
Details of the high altitude control pattern will be described. In the high altitude control pattern, the hybrid system controller 7 switches the negative pressure pump 4 when the calculated booster negative pressure value P is equal to or less than the starting negative pressure threshold u that can be changed according to the measured value W of the vehicle running speed. The negative pressure pump 4 is stopped when the booster negative pressure is calculated and the calculated value P of the booster negative pressure is greater than or equal to the stop negative pressure threshold v that can be changed according to the measured value W of the vehicle running speed.

[Change of starting and stopping negative pressure threshold in high altitude control pattern]
Changes in the starting and stopping negative pressure thresholds u and v in the high altitude control pattern will be described with reference to FIG. In FIG. 9, the horizontal axis indicates the measured value W (km / h) of the running speed of the automobile, the left vertical axis indicates the starting negative pressure threshold u (Pa), and the right vertical axis indicates the stop negative pressure. The threshold value v (Pa) is indicated. Further, in FIG. 9, the first and second starting negative pressure thresholds u1 and u2 set according to the change in travel speed are indicated by X, and the first and second start negative pressure thresholds u1 and u2 set according to the change in travel speed are shown. The second stop negative pressure threshold values v1 and v2 are indicated by circles. As shown in FIG. 9, the starting negative pressure threshold u is a first starting negative pressure threshold u1 when the measured value W of the traveling speed is in the starting low speed region, and the measured value W of the traveling speed is the starting high speed region. Is changed to the second starting negative pressure threshold value u2. The start low speed region is set in a range where the travel speed value W ′ is smaller than the start vehicle speed threshold z, and the start high speed region is set in a range where the travel speed value W ′ is equal to or greater than the start vehicle speed threshold z. The

  The second starting negative pressure threshold u2 is set larger than the first starting negative pressure threshold u1. As an example only, the first starting negative pressure threshold u1 is preferably about 47 kPa, and the second starting negative pressure threshold u2 is preferably about 60 kPa. The difference between the first and second starting negative pressure thresholds u1 and u2 is more preferably about 17 kPa. The starting vehicle speed threshold value z is preferably about 10 km / h or more and about 50 km / h or less.

  On the other hand, the stop negative pressure threshold value v is the first stop negative pressure threshold value v1 when the travel speed measurement value W is in the stop low speed region and the travel speed measurement value W when the travel speed measurement value W is in the stop high speed region. The second stop negative pressure threshold value v2 is changed. The stop low speed region is set in a range where the travel speed value W ′ is smaller than the stop vehicle speed threshold σ, and the stop high speed region is set in a range where the travel speed value W ′ is equal to or greater than the stop vehicle speed threshold σ. The

  The second stop negative pressure threshold v2 is set to be larger than the first stop negative pressure threshold v1. As an example to the last, the first stop negative pressure threshold v1 is preferably about 60 kPa, and the second stop negative pressure threshold v2 is preferably about 63 kPa. The difference between the first and second stop negative pressure threshold values v1 and v2 is more preferably about 3 kPa. The stop vehicle speed threshold σ is preferably about 10 km / h or more and about 50 km / h or less.

  A control flow for changing the start and stop negative pressure thresholds u and v will be described using a case where the vehicle is stopped in the initial state. As shown in FIG. 10, the automobile starts traveling (step STP41). The running speed is in the start or stop low speed region, and the start or stop negative pressure thresholds u and v become the first start or stop negative pressure thresholds u1 and v1 (step STP42). The hybrid system controller 7 estimates the measured value W of the traveling speed based on the current value, voltage value, etc. of an inverter (not shown) provided therein, or measures the traveling speed using the vehicle speed sensor 13. The travel speed measurement value W is sent to the ESP module 8, and the travel speed measurement value W is sent from the ESP module 8 to the hybrid system controller 7 as necessary. Using at least one of the hybrid system controller 7 and the ESP module 8, it is determined whether or not the measured value W of the traveling speed is greater than or equal to the starting or stopping vehicle speed threshold value z or σ (step STP43).

  When the measured value W of the travel speed is smaller than the start or stop vehicle speed threshold value z or σ (NO), the travel speed is in the start or stop low speed region, and the start or stop negative pressure threshold value u or v is set to the first start or stop. The negative pressure thresholds u1 and v1 are maintained (step STP42). On the other hand, when the measured value W of the travel speed is equal to or higher than the start or stop vehicle speed threshold value z, σ (YES), the travel speed is in the high speed region during start or stop, and the start or stop negative pressure threshold values u, v are set to the first value. The first start or stop negative pressure threshold u1, v1 is changed to the second start or stop negative pressure threshold u2, v2 (step STP44). Again, the hybrid system controller 7 estimates the measured value W of the traveling speed based on the current value, voltage value, etc. of an inverter (not shown) provided therein, or uses the vehicle speed sensor 13 to determine the traveling speed. Then, the measured value W of the traveling speed is sent to the ESP module 8, and the measured value W of the traveling speed is sent from the ESP module 8 to the hybrid system controller 7 as necessary. Using at least one of the hybrid system controller 7 and the ESP module 8, it is determined whether or not the measured value W of the traveling speed is equal to or greater than the starting or stopping vehicle speed threshold value z or σ (step STP45).

  When the measured value W of the travel speed is smaller than the start or stop vehicle speed threshold value z or σ (NO), the travel speed is in the start or stop low speed region, and the start or stop negative pressure threshold value u or v is set to the second start or stop. The negative pressure threshold values u2 and v2 are changed to the first start or stop negative pressure threshold values u1 and v1 (step STP42). On the other hand, when the measured value W of the travel speed is equal to or higher than the start or stop vehicle speed threshold value z, σ (YES), the travel speed is in the high speed region during start or stop, and the start or stop negative pressure threshold values u, v are set to the first value. 2 is maintained in the state of starting or stopping negative pressure thresholds u2 and v2 (step STP44).

[Relationship between low and high altitude control patterns]
With reference to FIG.7 and FIG.9, the relationship between the control pattern for lowlands and a highland is demonstrated. The first starting negative pressure threshold s1 of the low altitude control pattern is substantially equal to the first starting negative pressure threshold u1 of the high altitude control pattern. The second starting negative pressure threshold s2 of the low altitude control pattern is equal to or higher than the second starting negative pressure threshold u2 of the high altitude control pattern. The third starting negative pressure threshold s3 of the low altitude control pattern is larger than the second starting negative pressure threshold u2 of the high altitude control pattern.

  The first stop negative pressure threshold t1 of the low altitude control pattern is substantially equal to the first stop negative pressure threshold v1 of the high altitude control pattern. The second stop negative pressure threshold t2 of the low altitude control pattern is equal to or higher than the second stop negative pressure threshold v2 of the high altitude control pattern. The third stop negative pressure threshold t3 of the low altitude control pattern is larger than the second stop negative pressure threshold v2 of the high altitude control pattern.

[About action and effect]
As described above, according to the control method of the negative pressure pump 4 according to the present embodiment, even when the atmospheric pressure changes in the vicinity of the first or second atmospheric pressure thresholds b1 and b2, the lowland control pattern and the highland It can be prevented that the control pattern is frequently switched. As a result, the negative pressure pump 4 can be controlled stably, accurately and efficiently.

  Moreover, according to the control method of the negative pressure pump 4 according to the present embodiment, the booster negative pressure is changed in accordance with the change in the running speed of the automobile, so that the booster negative pressure is reduced due to the change in the running speed. It is possible to prevent the negative pressure pump 4 from continuing to operate due to the fact that the booster negative pressure required for assisting the brake cannot be secured. As a result, the number of start-ups of the negative pressure pump 4 can be reduced and the driving time of the negative pressure pump 4 can be shortened, so that the life of the negative pressure pump 4 is lengthened and the operating noise from the negative pressure pump 4 is reduced. The negative pressure pump 4 can be efficiently controlled so as to reduce the generation.

  Although the embodiment of the present invention has been described so far, the present invention is not limited to the above-described embodiment, and the present invention can be modified and changed based on its technical idea.

2 Vacuum booster 4 Negative pressure pump A Measured value of atmospheric pressure A ′ Atmospheric pressure value b1 First atmospheric pressure threshold b2 Second atmospheric pressure threshold H Altitude i1 First elevation threshold i2 Second elevation threshold D Booster absolute Measured pressure value D 'Booster absolute pressure value e Starting absolute pressure threshold (starting absolute pressure threshold for high altitude)
f Stop absolute pressure threshold (low start absolute pressure threshold)
P Calculated value of booster negative pressure q Starting negative pressure threshold (low starting negative pressure threshold)
r Stopping negative pressure threshold (low starting negative pressure threshold)
s Starting negative pressure threshold (low starting negative pressure threshold)
s1 1st starting negative pressure threshold (1st starting negative pressure threshold for low ground)
s2 Second starting negative pressure threshold (second starting low pressure threshold for low ground)
s3 Third starting negative pressure threshold (third low starting negative pressure threshold)
t Stopping negative pressure threshold (lowing stop negative pressure threshold)
t1 1st stop negative pressure threshold (1st stop negative pressure threshold for low ground)
t2 Second stop negative pressure threshold value (second low-land stop negative pressure threshold value)
t3 Third stop negative pressure threshold value (third low-land stop negative pressure threshold value)
u Starting negative pressure threshold (starting negative pressure threshold for high altitude)
u1 First starting negative pressure threshold (first starting high pressure negative pressure threshold)
u2 Second starting negative pressure threshold (second high altitude starting negative pressure threshold)
v Stop negative pressure threshold (high-land stop negative pressure threshold)
v1 first stop negative pressure threshold (first high altitude stop negative pressure threshold)
v2 Second stop negative pressure threshold (second high altitude stop negative pressure threshold)
W Measured value of traveling speed W ′ Traveling speed value x1 First starting vehicle speed threshold (first low-level starting vehicle speed threshold)
x2 Second start vehicle speed threshold (second low start vehicle speed threshold)
y1 1st stop vehicle speed threshold value (1st low land stop vehicle speed threshold value)
y2 2nd stop vehicle speed threshold value (2nd low vehicle stop vehicle speed threshold value)
z Start vehicle speed threshold (start vehicle speed threshold for high altitude)
σ Stop vehicle speed threshold (Highland stop vehicle speed threshold)
L one-dot chain line M1, M2 solid line N1, N2 two-dot chain line STP1-4, 11-14, 21-24, 31-38, 41-45 steps

Claims (2)

A method for controlling a negative pressure pump for an automobile that controls a negative pressure pump configured to generate a negative pressure in a vacuum booster of the automobile, wherein the negative pressure pump is controlled when the automobile is located in a lowland. A pattern switching step for switching between a lowland control pattern and a highland control pattern for controlling the negative pressure pump by a method different from the lowland control pattern when the vehicle is located at a high altitude higher than the lowland. In the control method of the negative pressure pump for automobiles including,
Low and high ground negative pressure threshold values respectively set as negative pressure values when starting or stopping the negative pressure pump in the low and high ground control patterns are changed according to the traveling speed of the vehicle. A threshold change step,
In the pattern switching step, a first atmospheric pressure threshold that is an atmospheric pressure value when switching from the lowland control pattern to the highland control pattern, and when switching from the highland control pattern to the lowland control pattern And a second atmospheric pressure threshold value that is greater than the first atmospheric pressure threshold value and different from the first atmospheric pressure threshold value ,
In the threshold value changing step, it is possible to change to a first lowland negative pressure threshold value, a second lowland negative pressure threshold value, and a third lowland negative pressure threshold value. The first highland negative pressure threshold can be changed to a second highland negative pressure threshold, and the first lowland negative pressure threshold is set equal to the first highland negative pressure threshold. A method for controlling a negative pressure pump for an automobile , wherein a low- pressure negative pressure threshold is set to be equal to or higher than the second high- pressure negative pressure threshold, and the third low-high negative pressure threshold is larger than the second high- pressure negative pressure threshold. . Said first negative pressure threshold for lowland, the traveling speed is the negative pressure threshold for lowland when in lowland low speed range,
The second negative pressure threshold for lowland, is said negative pressure threshold for lowland when the traveling speed is in a lowland medium speed region of the greater speed than the lowland low speed range, and for the first lowland The low-pressure negative pressure threshold value set larger than the negative pressure threshold value ,
The third negative pressure threshold for lowland, the running speed Ri said negative pressure threshold der for lowland when in lowland high-speed range of a greater rate than the in for lowland speed region, and the second lowland The low-pressure negative pressure threshold set larger than the negative pressure threshold for use ,
Said first negative pressure threshold for highlands, is said negative pressure threshold for highlands when the traveling speed is in a low speed range for high altitude,
The second negative pressure threshold for highlands, is said negative pressure threshold for highlands when in the high speed region in a large speed than the running speed the highland low speed range, and the first highland negative pressure a large set the negative pressure threshold for high altitude than the threshold, the control method of the vacuum pump for a motor vehicle according to claim 1.

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