JP2014201242A - Brake system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake system which can efficiently supply a suction chamber of a brake booster with negative pressure.SOLUTION: A brake system 1 comprises: a first passage L1; a check valve CV2; a bypass passage LA which bypasses a throttle valve 42; an ejector 30 which is disposed in the bypass passage LA and generates negative pressure; a vacuum switching valve VSV32 which controls flow rate of inflowing gas to the ejector 30; a second passage L2; an electrically-driven vacuum pump 18 which is disposed in the second passage L2; and a check valve CV4.

Description

  The present invention relates to a brake system having a brake booster that generates an assist force at a predetermined boost ratio with respect to the depression force of a brake pedal.

  With respect to the brake system, Patent Document 1 discloses that a nozzle is disposed on the upstream side of a diffuser connected to an intake pipe of an engine, and an ejector having a suction port opened between the nozzle and the diffuser. Discloses a technique for connecting a discharge port of a vacuum pump to the negative pressure chamber of a brake booster (pneumatic booster) via a suction port of the vacuum pump.

JP 2006-37868 A

  However, in the technique of Patent Document 1, negative pressure is directly supplied from the intake pipe to the negative pressure chamber of the brake booster via an ejector and a vacuum pump. However, the supply of negative pressure from the intake pipe has an influence on the restriction in the ejector. In particular, there is a delay in the supply of negative pressure into the negative pressure chamber of the brake booster particularly at the early stage of deceleration of the vehicle. Therefore, negative pressure is not efficiently supplied into the negative pressure chamber of the brake booster.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to provide a brake system that can efficiently supply negative pressure into the negative pressure chamber of a brake booster.

  One aspect of the present invention made in order to solve the above-described problems is a brake system, wherein a first passage connected to a negative pressure chamber of a brake booster and an intake system of an engine is provided on the first passage, A first check valve that prevents fluid from flowing from the intake system side to the negative pressure chamber side via the first passage; a first bypass passage that bypasses a throttle valve in the intake system; and the first An ejector provided on the bypass passage for generating a negative pressure; a flow control valve provided on the first bypass passage for controlling a flow rate of fluid flowing into the ejector; and the first check on the first passage. A second passage branched from a position on the negative pressure chamber side than the valve and connected to the suction port of the ejector; an electric vacuum pump provided on the second passage; and the ejector side via the second passage Before To have a second check valve to prevent fluid from flowing into the negative pressure chamber side, characterized by.

  According to this aspect, the negative pressure generated in the intake system is increased at a desired timing by the flow control valve while realizing a high negative pressure in the negative pressure chamber of the brake booster by the electric vacuum pump and the ejector. It can be supplied to the negative pressure chamber of the brake booster. Therefore, negative pressure can be efficiently supplied into the negative pressure chamber of the brake booster.

  In the above aspect, the vehicle has a vehicle speed detecting means for detecting the speed of the vehicle on which the brake system is mounted, and when the deceleration of the vehicle is detected by the vehicle speed detecting means, the valve closing control of the flow control valve is performed. It is preferable to do.

  According to this aspect, it is possible to increase the negative pressure generated in the intake system immediately after the vehicle on which the brake system is mounted starts deceleration. Therefore, the negative pressure can be efficiently supplied into the negative pressure chamber of the brake booster immediately after the vehicle starts to decelerate.

  In the above aspect, the negative pressure chamber pressure detecting means for detecting the pressure in the negative pressure chamber of the brake booster is provided, and even if the vehicle speed is detected by the vehicle speed detecting means, the negative pressure chamber is detected. When the pressure in the negative pressure chamber detected by the pressure detection means is equal to or lower than a predetermined pressure, it is preferable not to perform valve closing control of the flow rate control valve.

  According to this aspect, unnecessary power consumption by the flow control valve can be prevented when the pressure in the negative pressure chamber of the brake booster is equal to or lower than a predetermined pressure.

  In the above aspect, there is provided a rotational speed detection means for detecting the rotational speed of the engine, and even when the vehicle speed is detected by the vehicle speed detection means, the speed detected by the rotational speed detection means is detected. When the rotational speed is equal to or less than a predetermined value, it is preferable not to perform the valve closing control of the flow rate control valve.

  According to this aspect, it is possible to prevent the engine stall that may occur by closing the flow control valve when the engine speed is equal to or lower than the predetermined value.

  In the above aspect, the vehicle has fuel cut detection means for detecting whether or not the operating state of the engine is a fuel cut state, and even when the vehicle speed detection means detects deceleration of the vehicle, When the fuel cut detection means detects that the engine operating state is not the fuel cut state, it is preferable not to perform the valve closing control of the flow rate control valve.

  According to this aspect, it is possible to prevent engine misfire that may occur by closing the flow rate control valve when the engine operating state is not the fuel cut state.

  In the above aspect, it is preferable that the electric vacuum pump is operated when the flow control valve is in the open state and the pressure in the negative pressure chamber of the brake booster is equal to or higher than a predetermined pressure.

  According to this aspect, when the negative pressure in the negative pressure chamber of the brake booster is lower than a predetermined pressure, the negative pressure generated by the electric vacuum pump and the negative pressure generated by the ejector can be reduced by the negative pressure of the brake booster. High negative pressure in the room.

  In the above aspect, the third branched from the position on the ejector side of the electric vacuum pump on the second passage and connected to the position on the intake system side of the first check valve on the first passage. It is preferable to include a passage and a third check valve provided on the third passage and allowing only a fluid flow from the electric vacuum pump side to the intake system side.

  According to this aspect, the assist of the generation of the negative pressure by driving the electric vacuum pump can be performed at the higher one of the negative pressure in the intake system of the engine and the negative pressure generated by the suction of the ejector. Therefore, negative pressure can be supplied more efficiently into the negative pressure chamber of the brake booster. In addition, when the electric vacuum pump is driven, if the suction amount of the fluid in the ejector is insufficient with respect to the discharge flow rate of the electric vacuum pump, the driving of the electric vacuum pump can be assisted by the suction of the fluid from the third passage. it can.

  In the said aspect, it is preferable that the diameter of the said 1st channel | path is the largest among each channel | path.

  According to this aspect, a large amount of negative pressure in the intake system of the engine can be supplied to the negative pressure chamber of the brake booster. Therefore, the negative pressure in the negative pressure chamber of the brake booster can be increased in a short time. Further, by reducing the diameter of the passages other than the first passage, it is possible to improve the response (responsiveness) of the generation of negative pressure by driving the electric vacuum pump with respect to the electric vacuum pump that receives assistance by the suction of the ejector. it can.

  In the above aspect, a second bypass passage that bypasses the electric vacuum pump, and a fourth check valve that is provided on the second bypass passage and allows only a fluid flow from the negative pressure chamber side to the ejector side It is preferable to have.

  According to this aspect, when the electric vacuum pump is stopped, the ejector can supply negative pressure into the negative pressure chamber of the brake booster via the second bypass passage. Therefore, the negative pressure in the negative pressure chamber of the brake booster can be increased when the electric vacuum pump is stopped. Therefore, the time required to reach the target negative pressure required in the negative pressure chamber of the brake booster can be further shortened, and the negative pressure can be supplied more efficiently into the negative pressure chamber of the brake booster.

  Another aspect of the present invention made to solve the above-described problems is a brake system, the first passage connected to the negative pressure chamber of the brake booster and the intake system of the engine, and provided on the first passage, A first check valve that prevents fluid from flowing from the intake system side to the negative pressure chamber side via the first passage; a bypass passage that bypasses the throttle valve in the intake system; and An ejector for generating negative pressure, a flow rate control valve for controlling the flow rate of fluid flowing into the ejector on the bypass passage, and the negative check valve more than the first check valve on the first passage. A second passage branched from a position on the pressure chamber side and connected to the suction port of the ejector, and a second check for preventing fluid from flowing from the ejector side to the negative pressure chamber side via the second passage. Valve and brake Vehicle speed detection means for detecting the speed of the vehicle on which the system is mounted, and when the vehicle speed detection means detects deceleration of the vehicle, the flow rate control valve is controlled to close, When it is detected that a predetermined time has elapsed since the start of deceleration, the valve closing control is ended and the flow control valve is opened.

  According to this aspect, immediately after the vehicle starts to decelerate, the operation of the ejector is prohibited, whereby the negative pressure generated in the intake system is increased to a high negative pressure and supplied to the negative pressure chamber of the brake booster. . Therefore, immediately after the vehicle starts to decelerate, the ability to supply negative pressure to the negative pressure chamber of the brake booster can be increased. After that, since the ejector is operated, a negative pressure higher than the negative pressure generated in the intake system is supplied from the ejector to the negative pressure chamber of the brake booster, so that the brake braking ability can be enhanced.

  According to the brake system of this configuration, negative pressure can be efficiently supplied into the negative pressure chamber of the brake booster.

It is a schematic block diagram of the brake system of Example 1. It is sectional drawing which shows an example of a structure around an ejector. It is a block diagram which shows the control system of the brake system of Example 1. FIG. FIG. 3 is a diagram illustrating a control routine of the first embodiment. FIG. 4 is a diagram illustrating an example of a time chart of the first embodiment. It is a schematic block diagram of the brake system of the modification of Example 1. FIG. It is a schematic block diagram of the brake system of Example 2. FIG. 6 is a diagram illustrating a control routine of a second embodiment.

  DETAILED DESCRIPTION Hereinafter, an embodiment of a brake system according to the present invention will be described in detail with reference to the drawings. In the following description, “negative pressure” refers to a pressure lower than atmospheric pressure. Also, “high negative pressure” and “high negative pressure” mean that the difference from atmospheric pressure is large, and “low negative pressure” and “low negative pressure” mean that the difference from atmospheric pressure is small. Say.

[Example 1]
<Configuration and operation of brake system>
As shown in FIGS. 1 to 3, the brake system 1 of the present embodiment includes a brake pedal 10, a brake booster 12, a master cylinder 14, a negative pressure sensor 16, and an electric vacuum pump 18 (“electric VP” in the figure). ”, ECU 24, intake pipe pressure detection means 26, ejector 30, vacuum switching valve (hereinafter referred to as“ VSV ”) 32, vehicle speed sensor 34, rotation speed sensor 36, It includes a check valve CV1, a check valve CV2, a check valve CV3, a check valve CV4, and the like.

  As shown in FIG. 1, the brake booster 12 is provided between the brake pedal 10 and the master cylinder 14. The brake booster 12 generates an assist force with a predetermined boost ratio with respect to the depression force of the brake pedal 10.

  The inside of the brake booster 12 is partitioned by a diaphragm (not shown), and a negative pressure chamber (not shown) partitioned on the master cylinder 14 side and a variable pressure chamber (not shown) capable of introducing the atmosphere. Is provided. The negative pressure chamber of the brake booster 12 is connected to the engine intake pipe 40 via the first passage L1. That is, the first passage L <b> 1 is connected to the negative pressure chamber of the brake booster 12 and the intake pipe 40. As a result, the negative pressure generated in the intake pipe 40 in accordance with the opening of the throttle valve 42 (indicated as “THR” in FIG. 1) when the engine is driven is generated in the negative pressure chamber of the brake booster 12. Supplied through one passage L1. Here, the intake pipe 40 is an example of the “intake system” in the present invention.

  The master cylinder 14 increases the hydraulic pressure of the brake body (not shown) by the operation of the brake booster 12 and generates a braking force in the brake body. The negative pressure sensor 16 detects the pressure in the negative pressure chamber of the brake booster 12. The negative pressure sensor 16 is an example of the “negative pressure indoor pressure detecting means” in the present invention.

  As shown in FIG. 1, the electric vacuum pump 18 is provided on the second passage L2, and the suction port 18a is connected to the negative pressure chamber of the brake booster 12 via the second passage L2 and the first passage L1. Yes. Here, the second passage L2 is located on the first passage L1 from the position between the check valve CV1 and the check valve CV2 (the position on the negative pressure chamber side of the brake booster 12 with respect to the check valve CV2). This is a passage that branches off from one passage L <b> 1 and is connected to the suction port 30 c of the ejector 30.

  In addition, the electric vacuum pump 18 is connected to the ECU 24, and the driving of the electric vacuum pump 18 is controlled by the ECU 24. Specifically, the electric vacuum pump 18 starts driving based on a driving start signal from the ECU 24 and passes through the second passage L2 and the first passage L1 from the suction port 18a to the negative pressure chamber of the brake booster 12. Supply negative pressure to Further, the electric vacuum pump 18 stops driving based on a driving stop signal from the ECU 24, and negative pressure is supplied from the suction port 18a to the negative pressure chamber of the brake booster 12 through the second passage L2 and the first passage L1. Stop supplying.

  The check valve CV1 is provided at a position between the branch portion of the first passage L1 and the second passage L2 and the brake booster 12. The check valve CV2 is provided in the first passage L1 at a position closer to the intake pipe 40 than the check valve CV1 and between the branch portion of the second passage L2 and the intake pipe 40. Yes. Both the check valve CV1 and the check valve CV2 are configured to be opened only when the negative pressure on the intake pipe 40 side is higher than the negative pressure on the negative pressure chamber side of the brake booster 12. Only the fluid flow from the negative pressure chamber side of the booster 12 to the intake pipe 40 side is allowed. Specifically, the check valve CV1 prevents gas from flowing from the intake pipe 40 side to the negative pressure chamber side of the brake booster 12 through the first passage L1, and intake air through the second passage L2. Gas is prevented from flowing into the negative pressure chamber side of the brake booster 12 from the pipe 40 side. The check valve CV2 prevents gas from flowing from the intake pipe 40 side to the negative pressure chamber side of the brake booster 12 via the first passage L1, and the intake pipe 40 side via the first passage L1. In addition, gas is prevented from flowing from the discharge port 18b side of the electric vacuum pump 18 to the suction port 18a side of the electric vacuum pump. Thus, the brake system 1 of the present embodiment can contain negative pressure in the negative pressure chamber of the brake booster 12 by the check valve CV1 and the check valve CV2.

  The check valve CV2 is configured to open only when the negative pressure on the intake pipe 40 side is higher than the negative pressure on the negative pressure chamber side of the brake booster 12, as described above. Only the flow of fluid from the negative pressure chamber side to the intake pipe 40 side is allowed. Therefore, when the negative pressure generated by driving the electric vacuum pump 18 is higher than the negative pressure in the intake pipe 40 generated by driving the engine, the negative pressure generated by driving the electric vacuum pump 18 is reduced to the brake booster 12. The negative pressure chamber is supplied.

  The ECU 24 is configured by a microcomputer, for example, and includes a ROM that stores a control program, a readable / writable RAM that stores calculation results, a timer, a counter, an input interface, and an output interface. As shown in FIG. 3, the ECU 24 is connected to a negative pressure sensor 16, an electric vacuum pump 18, an intake pipe pressure detecting means 26, a VSV 32, a vehicle speed sensor 34, a rotation speed sensor 36, and the like. The ECU 24 can perform a brake system control method, which will be described in detail later. The ECU 24 also functions as fuel cut detection means for detecting whether or not the engine operating state is a deceleration fuel cut state. Further, the ECU 24 also functions as an elapsed time detection unit that detects an elapsed time after the vehicle starts decelerating.

  The brake system 1 configured as shown in FIG. 1 supplies the negative pressure in the intake pipe 40 to the negative pressure chamber of the brake booster 12 via the first passage L1, thereby Negative pressure can be adjusted. In addition, the brake system 1 also drives the electric vacuum pump 18 to supply a negative pressure into the negative pressure chamber of the brake booster 12 via the second passage L2 and the first passage L1, whereby the brake booster 12 The negative pressure in the negative pressure chamber can be adjusted.

  Here, the brake system 1 of the present embodiment includes an ejector 30 that is provided on the bypass passage LA and generates negative pressure, as shown in FIG. Here, the bypass passage LA is a passage provided in parallel with the intake pipe 40 and is a passage that bypasses the throttle valve 42. The bypass passage LA is an example of the “first bypass passage” or the “bypass passage” in the present invention.

  The structure around the ejector 30 is formed, for example, as shown in FIG. As shown in FIG. 2, the ejector 30 includes an inlet 30a, an outlet 30b, a suction port 30c, and the like. The suction port 30c includes a diaphragm 30d. When a gas flows from the inlet 30a toward the outlet 30b, the ejector 30 can generate a negative pressure by sucking the gas in the suction port 30c by the generated high-speed jet.

  In the brake system 1, the diameter of the first passage L1 connected to the intake pipe 40 is the largest of the first passage L1, the second passage L2, the third passage L3, and the bypass passage LA. Therefore, a large amount of gas in the negative pressure chamber of the brake booster 12 can be sucked into the intake pipe 40 via the first passage L1. Therefore, the negative pressure generated in the intake pipe 40 by driving the engine can increase the negative pressure in the negative pressure chamber of the brake booster 12 in a short time.

  The check valve CV3 is provided on the third passage L3 and allows only a gas flow from the electric vacuum pump 18 side to the intake pipe 40 side. Here, the third passage L3 branches from the position on the ejector 30 side of the electric vacuum pump 18 on the second passage L2, more specifically, from the position between the electric vacuum pump 18 and the check valve CV4. This is a passage connected to a position closer to the intake pipe 40 than the check valve CV2 on L1. Further, the check valve CV4 is provided at a position closer to the ejector 30 than the electric vacuum pump 18 on the second passage L2. This check valve CV4 allows only gas flow from the electric vacuum pump 18 side to the ejector 30 side, and gas flows from the ejector 30 side to the negative pressure chamber side of the brake booster 12 via the second passage L2. To prevent that.

  The VSV 32 is provided on the bypass passage LA. The VSV 32 is a flow rate control valve that controls the flow rate of the gas flowing into the ejector 30. The VSV 32 is a normally open type valve. Therefore, the ECU 24 can close the VSV 32 (fully closed state) by applying a driving voltage to an actuator (not shown) of the VSV 32.

  The vehicle speed sensor 34 detects the speed of the vehicle on which the brake system 1 is mounted, and is an example of the “vehicle speed detection means” in the present invention. Further, the rotational speed sensor 36 detects the engine rotational speed ne.

  As shown in FIG. 1, an airflow 44 and an air cleaner 46 are provided on the upstream side of the intake pipe 40 in addition to the throttle valve 42.

  In the brake system 1, the check valve CV2 is an example of the “first check valve” in the present invention, and the check valve CV4 is an example of the “second check valve” in the present invention. CV3 is an example of the “third check valve” in the present invention.

  Next, the operation of the brake system 1 configured as described above will be described. The brake system 1 supplies negative pressure (hereinafter referred to as “engine negative pressure”) generated in the intake pipe 40 by driving the engine to the negative pressure chamber of the brake booster 12 and is generated by driving the electric vacuum pump 18. Negative pressure (hereinafter referred to as “pump negative pressure”) can also be supplied to the negative pressure chamber of the brake booster 12. That is, in order to respond to the required negative pressure in the negative pressure chamber of the brake booster 12, in addition to supplying the engine negative pressure to the negative pressure chamber of the brake booster 12, supply of negative pump pressure to the negative pressure chamber of the brake booster 12 Assist by can be performed.

  The brake system 1 supplies negative pressure generated by suction of the ejector 30 (hereinafter referred to as “ejector negative pressure”) to the discharge port 18b of the electric vacuum pump 18 via the check valve CV4. Thereby, the drive load of the electric vacuum pump 18 can be reduced and the pump negative pressure can be further increased. That is, the drive of the electric vacuum pump 18 is assisted by the suction of the ejector 30.

<Brake system control method>
Next, a control method of the brake system 1 having the above configuration will be described.

  Specifically, the ECU 24 periodically executes the control routine shown in FIG. 4 every predetermined time.

  Therefore, when the processing of the routine shown in FIG. 4 is started, first, the ECU 24 determines the booster internal pressure bpm that is the pressure in the negative pressure chamber of the brake booster 12 and the engine intake pipe pressure pm that is the pressure in the intake pipe 40. The engine speed ne is taken in (steps S1, S2).

  Next, the ECU 24 determines whether or not the vehicle on which the brake system 1 is mounted is immediately after deceleration (step S3). In this way, the ECU 24 determines whether or not the vehicle speed sensor 34 has detected deceleration of the vehicle, that is, whether or not the brake pedal 10 has been depressed to decelerate the vehicle. As an example, the ECU 24 determines whether it is within 1 to 2 seconds from when the vehicle starts to decelerate.

  When the vehicle is immediately after deceleration in step S3, the ECU 24 determines whether or not the booster internal pressure bpm is greater than a predetermined pressure (A-α) (step S4). That is, the ECU 24 determines whether or not the negative pressure in the negative pressure chamber of the brake booster 12 is lower than the predetermined pressure (A−α). The booster internal pressure bpm is detected by the negative pressure sensor 16. Further, the predetermined pressure (A−α) is set to −80 kPa, for example.

  When the booster internal pressure bpm is larger than the predetermined pressure (A−α) in step S4, the ECU 24 determines whether or not the engine speed ne is higher than the predetermined value B (step S5). As an example, the predetermined value B is set to a rotational speed that is 300 rpm higher than the engine rotational speed ne when the engine is in an idle operation state.

  If the engine speed ne is higher than the predetermined value B in step S5, the ECU 24 determines whether or not the engine is in a deceleration fuel cut state (deceleration F / C state) (step S6).

  When the engine is in the deceleration fuel cut state in step S6, the ECU 24 closes the VSV 32 (fully closed state) (step S7), and temporarily terminates the routine processing. That is, the ECU 24 performs the valve closing control of the VSV 32 when the VSV 32 is in the valve open state, and closes the VSV 32, and continues the valve closing control of the VSV 32 when the VSV 32 is in the valve closed state. The VSV 32 is kept closed.

  Further, when the vehicle is not immediately after deceleration in step S3, when the engine speed ne is equal to or less than the predetermined value B in step S5, or when the engine is not in the deceleration fuel cut state in step S6, the ECU 24 It is determined whether or not the P operation flag Xvp = 0 (step S8). Here, when the electric vacuum pump 18 is stopped, the V / P operation flag Xvp = 0 is set, and when the electric vacuum pump 18 is operated, the V / P operation flag Xvp = 1 is set. The

  When the V / P operation flag Xvp = 0 in step S8, the ECU 24 determines whether or not the booster internal pressure bpm is smaller than the predetermined pressure A (step S9). That is, the ECU 24 determines whether or not the negative pressure in the negative pressure chamber of the brake booster 12 is higher than the predetermined pressure A. The predetermined pressure A is, for example, −65 kPa.

  If the booster internal pressure bpm is smaller than the predetermined pressure A in step S9, the ECU 24 stops the electric vacuum pump 18 (step S10), opens the VSV 32 (step S11), and temporarily executes the routine processing. finish. That is, in step S11, the ECU 24 ends the valve closing control of the VSV 32 when the VSV 32 is in the closed state, opens the VSV 32, and closes the VSV 32 when the VSV 32 is in the opened state. The VSV 32 is kept open without performing control. In step S10, the ECU 24 sets the V / P operation flag Xvp = 0.

  On the other hand, when the booster internal pressure bpm is equal to or higher than the predetermined pressure A in step S9, the ECU 24 operates the electric vacuum pump 18 (step S12), opens the VSV 32 (step S11), and temporarily executes the routine processing. finish. In step S12, the ECU 24 sets the V / P operation flag Xvp = 1.

  If the booster internal pressure bpm is equal to or lower than the predetermined pressure (A−α) in step S4, the ECU 24 proceeds to control in step S10. That is, even if it is immediately after deceleration (step S3: YES), if the booster internal pressure bpm is equal to or lower than the predetermined pressure (A-α) (step S4: NO), the ECU 24 turns the electric vacuum pump 18 on. Stop (step S10), the VSV 32 is opened without performing the valve closing control of the VSV 32 (step S11).

  When the V / P operation flag Xvp = 1 in step S8, the ECU 24 determines whether or not the booster internal pressure bpm is smaller than a predetermined pressure (A−α) (step S13). If the booster internal pressure bpm is smaller than the predetermined pressure (A−α) in step S13, the ECU 24 stops the electric vacuum pump 18 (step S14), similarly to steps S10 and S11, and the VSV 32 Without performing the valve closing control, the VSV 32 is opened (step S15), and the routine processing is temporarily ended. On the other hand, when the booster internal pressure bpm is equal to or higher than the predetermined pressure (A−α) in step S13, the ECU 24 operates the electric vacuum pump 18 (step S16) in the same manner as in steps S11 and S12. Without performing the valve closing control, the VSV 32 is opened (step S15), and the routine processing is temporarily ended.

  In this way, the ECU 24 performs the valve closing control of the VSV 32 when the vehicle speed sensor 34 detects the deceleration of the vehicle. Here, the valve closing control of the VSV 32 is a control for applying a driving voltage to an actuator (not shown) of the VSV 32 to change the VSV 32 from the valve opening state to the valve closing state.

  However, even when the deceleration of the vehicle is detected by the vehicle speed sensor 34, the ECU 24 determines that the VSV 32 does not operate when the booster internal pressure bpm detected by the negative pressure sensor 16 is equal to or lower than a predetermined pressure (A-α). The VSV 32 is kept open without performing the valve closing control.

  Further, even when the vehicle speed sensor 34 detects deceleration of the vehicle, the ECU 24 controls the valve closing of the VSV 32 if the engine speed ne detected by the speed sensor 36 is equal to or less than a predetermined value B. The VSV 32 is kept open without performing the above.

  Further, even when the vehicle speed sensor 34 detects the deceleration of the vehicle, the ECU 24 does not perform the valve closing control of the VSV 32 if it is detected that the engine operating state is not the deceleration fuel cut state. The VSV 32 is kept open.

  Further, when the VSV 32 is opened, the ECU 24 operates the electric vacuum pump 18 when the booster internal pressure bpm is equal to or higher than the predetermined pressure A or the predetermined pressure (A−α).

  The above is the description regarding the control routine shown in FIG.

  And the brake system 1 can perform an example of control as shown, for example in FIG. 5, when ECU24 performs the control routine shown in FIG. 4 periodically for every predetermined time.

  As shown in FIG. 5, at time T1, when the deceleration of the vehicle is detected, the ECU 24 specifically depresses the brake pedal 10 (deceleration determination is switched from “OFF” to “ON”). The booster internal pressure bpm is greater than the predetermined pressure (A-α), the engine speed ne is greater than the predetermined value B, and the engine is detected to start decelerating. When the operating state is a deceleration fuel cut state, the valve closing control of the VSV 32 is performed to bring the VSV 32 in the valve opening state into the valve closing state. Then, the ECU 24 subsequently performs the valve closing control of the VSV 32, and then, at time T2, a predetermined time (for example, 1 second to 2 seconds) has elapsed since the vehicle started to be decelerated (time T1). Is detected, the valve closing control of the VSV 32 is terminated and the VSV 32 is opened.

  Thus, immediately after the vehicle starts to decelerate (from time T1 to time T2), the ECU 24 closes the VSV 32. Thereby, since gas does not flow into the bypass passage LA, the engine negative pressure (engine intake pipe pressure pm) is increased to a high negative pressure. And since the engine negative pressure in which the negative pressure was increased is supplied to the negative pressure chamber of the brake booster 12, the negative pressure chamber of the brake booster 12 is increased in a short time. In FIG. 5, the engine intake pipe pressure pm0 when the VSV 32 is opened is indicated by a dotted line.

  Then (after time T2), the ECU 24 opens the VSV 32. As a result, the ejector negative pressure pmeje is supplied to the negative pressure chamber of the brake booster 12, so that the negative pressure chamber of the brake booster 12 is further increased in negative pressure as shown in FIG. In FIG. 5, the booster internal pressure bpm0 when the ejector negative pressure pmeje is not supplied to the negative pressure chamber of the brake booster 12 is indicated by a one-dot chain line.

  Further, when the VSV 32 is in the valve open state at time T3, the booster internal pressure bpm is larger than the predetermined pressure A (a low negative pressure), so the ECU 24 operates the electric vacuum pump 18. Thereby, since the pump negative pressure is supplied to the negative pressure chamber of the brake booster 12, the negative pressure chamber of the brake booster 12 is made highly negative. At this time, the electric vacuum pump 18 supplies the pump negative pressure to the negative pressure chamber of the brake booster 12 while receiving the assist of the ejector negative pressure pmeje.

  As described above, the ECU 24 performs the valve closing control of the VSV 32 immediately after deceleration to increase the engine negative pressure and supply the engine negative pressure to the negative pressure chamber of the brake booster 12. Increase the negative pressure in the 12 negative pressure chambers. Thereafter, the VSV 32 is opened, and the ejector negative pressure is supplied to the negative pressure chamber of the brake booster 12, thereby increasing the negative pressure in the negative pressure chamber of the brake booster 12.

<Effect of this embodiment>
The brake system 1 includes a first passage L1 connected to the negative pressure chamber of the brake booster 12 and the intake pipe 40, and the brake booster 12 is provided on the first passage L1 from the intake pipe 40 side through the first passage L1. And a check valve CV2 that prevents gas from flowing into the negative pressure chamber. The brake system 1 includes a bypass passage LA that bypasses the throttle valve 42 in the intake pipe 40, an ejector 30 that is provided on the bypass passage LA and generates negative pressure, and that flows into the ejector 30 provided on the bypass passage LA. VSV 32 for controlling the flow rate of the gas to be used. Further, the brake system 1 includes a second passage L2 that branches from a position on the negative pressure chamber side of the brake booster 12 relative to the check valve CV2 on the first passage L1 and is connected to the suction port 30c of the ejector 30; An electric vacuum pump 18 provided on the passage L2 and a check valve CV4 that prevents gas from flowing from the ejector 30 side to the negative pressure chamber side of the brake booster 12 via the second passage L2.

  Thus, the brake system 1 includes the electric vacuum pump 18 and the ejector on the second passage L2 and the bypass passage LA which are different from the first passage L1 connected to the negative pressure chamber of the brake booster 12 and the intake pipe 40. 30 is provided. Thus, immediately after the vehicle starts to decelerate, the engine negative pressure can be supplied to the negative pressure chamber of the brake booster 12 in a short time, and the pump negative pressure can be supplied to the negative pressure chamber of the brake booster 12 while being assisted by the ejector negative pressure. Can be supplied into the pressure chamber.

  The brake system 1 achieves a high negative pressure in the negative pressure chamber of the brake booster 12 by the electric vacuum pump 18 and the ejector 30, while increasing the negative pressure of the engine at a desired timing by the VSV 32. Can be supplied to the negative pressure chamber. Therefore, negative pressure can be efficiently supplied into the negative pressure chamber of the brake booster.

  The brake system 1 also has a vehicle speed sensor 34 that detects the speed of the vehicle, and performs valve closing control of the VSV 32 when deceleration of the vehicle is detected by the vehicle speed sensor 34. Thereby, the engine negative pressure can be increased to a high negative pressure immediately after the vehicle starts to decelerate. Therefore, immediately after the vehicle starts to decelerate, the engine negative pressure having a high negative pressure is supplied to the negative pressure chamber of the brake booster 12. In this way, the negative pressure can be efficiently supplied into the negative pressure chamber of the brake booster 12.

  The brake system 1 also includes a negative pressure sensor 16 that detects the booster internal pressure bpm. And even if it is a case where deceleration of a vehicle is detected by the vehicle speed sensor 34, the brake system 1 is, when the booster internal pressure bpm detected by the negative pressure sensor 16 is below a predetermined pressure (A-α), The valve closing control of the VSV 32 is not performed. Here, when the booster internal pressure bpm is equal to or lower than the predetermined pressure (A−α), that is, when the negative pressure in the negative pressure chamber of the brake booster 12 reaches the target negative pressure, it is necessary to perform the valve closing control of the VSV 32. There is no. For this reason, by not performing the valve closing control of the VSV 32 as described above, it is possible to prevent the power consumption generated by the unnecessary valve closing operation of the VSV 32.

  Moreover, the brake system 1 has a rotation speed sensor 36 that detects the engine rotation speed ne. Even when the deceleration of the vehicle is detected by the vehicle speed sensor 34, the brake system 1 closes the VSV 32 if the engine speed ne detected by the rotation speed sensor 36 is equal to or less than the predetermined value B. Valve control is not performed. Thereby, when the engine speed ne is equal to or less than the predetermined value B, it is possible to prevent a vehicle stall that may occur by closing the VSV 32. That is, when the VSV 32 is closed, gas is not supplied to the engine via the bypass passage LA, so that the intake amount to the engine is reduced. If the intake air amount of the engine decreases when the engine speed ne is low, the vehicle may be stalled. Therefore, when the engine speed ne is equal to or less than the predetermined value B, the gas is supplied to the engine through the bypass passage LA to maintain the intake amount to the engine by keeping the VSV 32 open. The vehicle stall can be prevented.

  Further, even when the vehicle speed sensor 34 detects the deceleration of the vehicle, the brake system 1 performs the valve closing control of the VSV 32 if the ECU 24 detects that the engine operating state is not the deceleration fuel cut state. Not performed. Thereby, when the engine operating state is not the deceleration fuel cut state, it is possible to prevent engine misfire that may occur by closing the VSV 32.

  The brake system 1 operates the electric vacuum pump 18 when the booster internal pressure bpm is equal to or higher than the predetermined pressure A or equal to or higher than the predetermined pressure (A−α) when the VSV 32 is in the valve open state. Thereby, when the negative pressure in the negative pressure chamber of the brake booster 12 does not reach the target negative pressure, the negative pressure chamber of the brake booster 12 can be increased to a high negative pressure by the pump negative pressure and the ejector negative pressure.

  In addition, the brake system 1 branches from the position on the ejector 30 side of the electric vacuum pump 18 on the second passage L2 and is connected to the position on the intake pipe 40 side of the check valve CV2 on the first passage L1. A passage L3 is provided. The brake system 1 includes a check valve CV3 that is provided on the third passage L3 and allows only a gas flow from the electric vacuum pump 18 side to the intake pipe 40 side. Thereby, the assist of generation | occurrence | production of a pump negative pressure can be performed by the higher one of an engine negative pressure and an ejector negative pressure. As a result, the negative pressure in the negative pressure chamber of the brake booster 12 can be efficiently increased. Therefore, the negative pressure can be supplied more efficiently into the negative pressure chamber of the brake booster 12. Further, when the electric vacuum pump 18 is driven, when the gas suction amount of the ejector 30 is insufficient with respect to the gas discharge flow rate of the electric vacuum pump 18, the driving of the electric vacuum pump 18 by the suction of the gas from the third passage L <b> 3. Can assist.

  Moreover, in the brake system 1, the diameter of the 1st channel | path L1 is the largest among each channel | path. As a result, a large amount of engine negative pressure can be supplied to the negative pressure chamber of the brake booster 12. Therefore, the negative pressure in the negative pressure chamber of the brake booster 12 can be increased to a high negative pressure in a short time. Further, by reducing the diameter of the passages other than the first passage L1, it is possible to improve the response (responsiveness) of the generation of the pump negative pressure in the electric vacuum pump 18 that receives the assist by the suction of the ejector 30.

  As a modification of the first embodiment, the control routine of FIG. 4 does not include a determination step (step S5) regarding the height of the engine speed ne and a determination step (step S6) regarding the presence or absence of the deceleration fuel cut state. Examples are also possible. That is, immediately after the vehicle starts decelerating and the booster internal pressure bpm is larger than the predetermined pressure (A-α), regardless of the height of the engine speed ne and the presence or absence of the deceleration fuel cut state, It is good also as performing valve closing control of VSV32.

  As a modification of the first embodiment, a brake system 1A as shown in FIG. 6 is also conceivable. As shown in FIG. 6, the brake system 1 </ b> A has a bypass passage LB that bypasses the electric vacuum pump 18 as a different point from the brake system 1. This bypass passage LB is a passage provided in parallel with the second passage L2, and is connected to the second passage L2. Further, the brake system 1A includes a check valve CV5 provided on the bypass passage LB. This check valve CV5 allows only a gas flow from the negative pressure chamber side of the brake booster 12 to the ejector 30 side. The bypass passage LB is an example of the “second bypass passage” in the present invention. The check valve CV5 is an example of the “fourth check valve” (a check valve on the second bypass passage) in the present invention.

  Since the brake system 1A has the bypass passage LB and the check valve CV5 as described above, when the electric vacuum pump 18 is stopped, the ejector 30 supplies negative pressure to the negative pressure chamber of the brake booster 12 via the bypass passage LB. Is done. Therefore, the negative pressure in the negative pressure chamber of the brake booster 12 can be increased when the electric vacuum pump 18 is stopped.

  Thereafter, the throttle opening is decreased and the electric vacuum pump 18 is driven. Then, engine negative pressure is supplied into the negative pressure chamber of the brake booster 12, and pump negative pressure is supplied into the negative pressure chamber of the brake booster 12. Further, the ejector 30 supplies negative pressure into the negative pressure chamber of the brake booster 12 through the second passage L2, the bypass passage LB, the second passage L2, and the first passage L1 in order.

  In such a brake system 1A, as described above, when the electric vacuum pump 18 is stopped, negative pressure is supplied to the negative pressure chamber of the brake booster 12 by the ejector 30, so that the negative pressure chamber of the brake booster 12 is supplied. The negative pressure can be increased. Further, in the brake system 1A, the negative pressure in the negative pressure chamber of the brake booster 12 is increased since the negative pressure is supplied to the negative pressure chamber of the brake booster 12 by the ejector 30 when the electric vacuum pump 18 is driven. Can be promoted. Therefore, the brake system 1 </ b> A is shorter than the brake system 1 until the target negative pressure required in the negative pressure chamber in the brake booster 12 is reached. Therefore, the brake system 1A can supply the negative pressure more efficiently into the negative pressure chamber of the brake booster 12.

[Example 2]
Next, the second embodiment will be described. The same components as those of the first embodiment are denoted by the same reference numerals, the description thereof will be omitted, and different points will be mainly described.

<Brake system configuration>
As shown in FIG. 7, the brake system 2 does not have the electric vacuum pump 18 as a difference from the brake system 1.

<Brake system control method>
Next, a control method of the brake system 2 configured as described above will be described.

  Specifically, the ECU 24 periodically executes the control routine shown in FIG. 8 every predetermined time.

  The control routine shown in FIG. 8 differs from the control routine shown in FIG. 4 in that there is no command related to the operation / stop of the electric vacuum pump 18. Then, according to the control routine shown in FIG. 8, as in the control routine shown in FIG. 4, the vehicle is immediately after deceleration (step S23: YES), and the booster internal pressure bpm is a predetermined pressure (A-α). (Step S24: YES), the engine speed ne is larger than the predetermined value B (step S25: YES), and the engine operating state is a deceleration fuel cut state (step S26: YES). When satisfy | filling, ECU24 performs valve closing control of VSV32, and makes VSV32 a valve closing state (step S27). If the above condition is not satisfied, the ECU 24 opens the VSV 32 without performing the valve closing control of the VSV 32 (step S28).

  The ECU 24 can perform the following control by periodically executing the control routine shown in FIG. 8 every predetermined time. That is, when the deceleration of the vehicle is detected, specifically, the ECU 24 depresses the brake pedal 10 (deceleration determination is switched from “OFF” to “ON”), and the deceleration of the vehicle is started. Is detected, the booster internal pressure bpm is greater than the predetermined pressure (A-α), the engine speed ne is greater than the predetermined value B, and the engine operating state is the deceleration fuel cut state. The valve closing control of the VSV 32 is performed. Then, the ECU 24 subsequently performs the valve closing control of the VSV 32 and then detects that a predetermined time (for example, 1 second to 2 seconds) has elapsed since the start of deceleration of the vehicle. Is closed and the VSV 32 is opened.

<Effect of this embodiment>
According to the second embodiment, in addition to the effects of the first embodiment, the following effects can be obtained.

  The brake system 2 is provided on the first passage L1 and the first passage L1 connected to the negative pressure chamber of the brake booster 12 and the intake pipe 40, and the brake booster 12 from the intake pipe 40 side through the first passage L1. And a check valve CV2 that prevents gas from flowing into the negative pressure chamber side. The brake system 2 includes a bypass passage LA that bypasses the throttle valve 42 in the intake pipe 40, an ejector 30 that is provided on the bypass passage LA and generates negative pressure, and that flows into the ejector 30 that is provided on the bypass passage LA. VSV 32 for controlling the flow rate of the gas to be used. Further, the brake system 2 includes a second passage L2 that branches from a position on the negative pressure chamber side of the brake booster 12 relative to the check valve CV2 on the first passage L1 and is connected to the suction port 30c of the ejector 30; And a check valve CV4 that prevents gas from flowing from the ejector 30 side to the negative pressure chamber side of the brake booster 12 through the passage L2. Furthermore, the brake system 2 includes a vehicle speed sensor 34 that detects the speed of the vehicle on which the brake system 2 is mounted. The brake system 2 performs the valve closing control of the VSV 32 when the vehicle speed sensor 34 detects the deceleration of the vehicle, and the VSV 32 detects that a predetermined time has elapsed since the vehicle deceleration was started. Is closed and the VSV 32 is opened.

  Thus, immediately after the vehicle starts to decelerate, the engine negative pressure is increased to a high negative pressure, so that the engine negative pressure having the increased negative pressure is supplied to the negative pressure chamber of the brake booster 12. Therefore, immediately after the vehicle starts to decelerate, the ability to supply negative pressure to the negative pressure chamber of the brake booster 12 can be increased. Then, since the ejector 30 is operated with the VSV 32 opened, an ejector negative pressure higher than the engine negative pressure is supplied from the ejector 30 to the negative pressure chamber of the brake booster 12 to increase the brake braking capability. be able to.

  It should be noted that the above-described embodiment is merely an example and does not limit the present invention in any way, and various improvements and modifications can be made without departing from the scope of the invention.

1, 1A, 2 Brake system 10 Brake pedal 12 Brake booster 14 Master cylinder 16 Negative pressure sensor 18 Electric vacuum pump (electric VP)
18a Suction port 18b Discharge port 24 ECU
26 Intake pipe pressure detection means 30 Ejector 30a Inlet 30b Outlet 30c Suction port 30d Restriction 32 VSV (vacuum switching valve)
34 Vehicle speed sensor 36 Rotational speed sensor 40 Intake pipe 42 Throttle valve 44 Air flow 46 Air cleaner CV1 to CV5 Check valve L1 First passage L2 Second passage L3 Third passage LA Bypass passage LB Bypass passage A Predetermined pressure α Predetermined pressure B Predetermined value pm Engine intake pipe pressure bpm Booster internal pressure pmeje Ejector negative pressure ne Engine speed

Claims (10)

A first passage connected to the negative pressure chamber of the brake booster and the intake system of the engine;
A first check valve provided on the first passage to prevent fluid from flowing from the intake system side to the negative pressure chamber side through the first passage;
A first bypass passage that bypasses the throttle valve in the intake system;
An ejector provided on the first bypass passage for generating a negative pressure;
A flow rate control valve provided on the first bypass passage for controlling the flow rate of fluid flowing into the ejector;
A second passage branched from the position on the negative pressure chamber side of the first check valve on the first passage and connected to the suction port of the ejector;
An electric vacuum pump provided on the second passage;
A second check valve for preventing fluid from flowing from the ejector side to the negative pressure chamber side through the second passage;
Brake system characterized by The brake system of claim 1,
Vehicle speed detecting means for detecting the speed of a vehicle on which the brake system is mounted;
Performing valve closing control of the flow control valve when deceleration of the vehicle is detected by the vehicle speed detecting means;
Brake system characterized by The brake system of claim 2,
Negative pressure chamber pressure detecting means for detecting the pressure in the negative pressure chamber of the brake booster;
Even when the deceleration of the vehicle is detected by the vehicle speed detecting means, the flow control valve is used when the pressure in the negative pressure chamber detected by the negative pressure chamber pressure detecting means is not more than a predetermined pressure. Do not perform valve closing control,
Brake system characterized by The brake system according to claim 2 or 3,
A rotation speed detecting means for detecting the rotation speed of the engine;
Even when deceleration of the vehicle is detected by the vehicle speed detection means, if the rotation speed detected by the rotation speed detection means is less than or equal to a predetermined value, valve closing control of the flow rate control valve is performed. Not to do,
Brake system characterized by The brake system according to any one of claims 2 to 4,
A fuel cut detecting means for detecting whether or not the operating state of the engine is a fuel cut state;
Even when the deceleration of the vehicle is detected by the vehicle speed detection means, the flow control valve is closed when the fuel cut detection means detects that the engine operating state is not the fuel cut state. No control,
Brake system characterized by The brake system according to claim 1 or 2,
When the flow control valve is in an open state and the pressure in the negative pressure chamber of the brake booster is equal to or higher than a predetermined pressure, operating the electric vacuum pump;
Brake system characterized by The brake system according to any one of claims 1 to 6,
A third passage branching from a position on the ejector side of the electric vacuum pump on the second passage and connected to a position on the intake system side of the first check valve on the first passage;
A third check valve provided on the third passage and allowing only a fluid flow from the electric vacuum pump side to the intake system side,
Brake system characterized by The brake system according to any one of claims 1 to 7,
The diameter of the first passage is the largest among the passages;
Brake system characterized by The brake system according to any one of claims 1 to 8,
A second bypass passage for bypassing the electric vacuum pump;
A fourth check valve provided on the second bypass passage and allowing only a fluid flow from the negative pressure chamber side to the ejector side,
Brake system characterized by A first passage connected to the negative pressure chamber of the brake booster and the intake system of the engine;
A first check valve provided on the first passage to prevent fluid from flowing from the intake system side to the negative pressure chamber side through the first passage;
A bypass passage for bypassing the throttle valve in the intake system;
An ejector provided on the bypass passage for generating a negative pressure;
A flow rate control valve provided on the bypass passage for controlling the flow rate of the fluid flowing into the ejector;
A second passage branched from the position on the negative pressure chamber side of the first check valve on the first passage and connected to the suction port of the ejector;
A second check valve for preventing fluid from flowing from the ejector side to the negative pressure chamber side through the second passage;
Vehicle speed detecting means for detecting the speed of the vehicle on which the brake system is mounted,
When deceleration of the vehicle is detected by the vehicle speed detecting means, valve closing control of the flow rate control valve is performed,
Ending the valve closing control and opening the flow control valve when it is detected that a predetermined time has elapsed since the vehicle started decelerating,
Brake system characterized by

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