Brake system

Abstract

The present invention provides a braking system capable of appropriately ensuring the negative pressure necessary to activate the brake booster while the vehicle is in motion. [Solution] The system comprises a brake booster 5 that assists the driver's braking force using negative pressure, a drive shaft negative pressure pump 6 that creates a negative pressure state inside the brake booster 5, and a drive force transmission unit 7 that transmits the driving force transmitted to the drive shaft 15 to the drive shaft negative pressure pump 6 to move the vehicle 2.

Description

[[Technical Field]]

[0001] The present invention relates to a brake device. [[Background Art]]

[0002] Among components constituting a brake device for vehicles such as hybrid vehicles (HV), plug-in hybrid vehicles (PHEV) capable of external charging and external power supply, electric vehicles, and gasoline engine vehicles, there is a brake booster for reducing a driver's brake operating force. This brake booster generates a high braking force by assisting the force acting on the rod of the cylinder in synchronization with the driver's brake operation, by means of the pressure difference between the internal negative pressure and the atmospheric pressure.

[0003] As a method for bringing the brake booster into a negative pressure state, for example, in Patent Document 1 below, negative pressure is secured by connecting an engine 25 and an electric negative pressure pump 66 to a negative pressure tank 69 (see especially paragraphs 0024 to 0030 and Fig. 2 of Patent Document 1). Further, in Patent Document 2 below, the engine 10 drives an air pump 52 to secure negative pressure in an air tank 53 (see especially paragraphs 0028 to 0032 and Fig. 1 of Patent Document 2). [[Prior Art Documents]] [[Patent Documents]]

[0004] [[Patent Document 1]] Japanese Unexamined Patent Publication No. 2017-100569 [[Patent Document 2]] Japanese Unexamined Patent Publication No. 2017-218024 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0005] In the configurations shown in Patent Documents 1 and 2, the pump is driven by the engine's driving force. However, in hybrid vehicles and plug-in hybrid vehicles, the engine may be controlled to stop during electric driving, and it is not possible to secure negative pressure during this stoppage. It is also possible to generate negative pressure by operating an electric vacuum motor while the engine is stopped, but providing a separate electric vacuum motor increases costs and consumes battery power when operating the electric vacuum motor.

[0006] Therefore, the objective of this invention is to provide a braking device that can appropriately secure negative pressure for operating a brake booster while the vehicle is in motion. [Means for solving the problem]

[0007] In order to solve the above problems, this invention provides: A brake booster that uses negative pressure to assist the driver's braking force, A drive shaft vacuum pump that creates a negative pressure state inside the brake booster, A drive force transmission unit that transmits the driving force transmitted to the drive shaft to the drive shaft vacuum pump for driving the vehicle, A brake device having the following characteristics was configured (first configuration).

[0008] In the first configuration, The system can be further configured (second configuration) with a clutch that switches between a disconnected state in which the transmission of driving force between the drive shaft and the drive shaft vacuum pump is interrupted and a transmitted state in which driving force is transmitted.

[0009] In the second configuration, It further includes a vehicle speed sensor that measures vehicle speed, The system can be configured (third configuration) in which the clutch is disengaged when the vehicle speed sensor detects acceleration or constant speed driving of the vehicle, and the clutch is engaged when the vehicle deceleration is detected.

[0010] In the third configuration, A configuration (fourth configuration) can be used in which the clutch is controlled to disengage when a vehicle speed below a predetermined vehicle speed is detected during deceleration.

[0011] In the fourth configuration, The vehicle further comprises a drive motor for propelling the vehicle and a battery for supplying power to the drive motor, A configuration (fifth configuration) can be used in which the predetermined vehicle speed is reduced to a lower speed when the battery charge level is equal to or greater than a predetermined charge level.

[0012] In the second through fifth configurations, It further includes a gradient sensor for measuring the road gradient, A configuration (sixth configuration) can be configured to control the clutch to a disengaged state when a gradient exceeding a predetermined gradient is detected.

[0013] In the second through sixth configurations, The vehicle further comprises a drive motor for propelling the vehicle and a battery for supplying power to the drive motor, The system can be configured (seventh configuration) to control the clutch to a disengaged state when the battery charge level is below a predetermined charge level.

[0014] In the second through seventh configurations, The clutch can be configured to allow manual switching between the disengaged state and the transmission state (8th configuration). [Effects of the Invention]

[0015] The brake device according to this invention transmits the driving force for moving the vehicle, which is transmitted to the drive shaft, to the drive shaft vacuum pump via the drive force transmission unit. Therefore, even when the engine is stopped while the vehicle is running, for example in a hybrid vehicle, it is possible to appropriately secure the vacuum pressure necessary to operate the brake booster while the vehicle is running. [Brief explanation of the drawing]

[0016] [Figure 1] It is a schematic diagram of a vehicle equipped with the brake device according to the present invention. [Figure 2] It is a schematic diagram of a main part of the brake device mounted on the vehicle shown in FIG. 1. [Figure 3] It is a diagram showing an example of a traveling pattern of the vehicle shown in FIG. 1. Mode for Carrying Out the Invention

[0017] An embodiment of a brake device 1 according to the present invention will be described with reference to the drawings. This brake device 1 can be applied to a vehicle 2 such as a hybrid vehicle (HV), a plug-in hybrid vehicle (PHEV) capable of external charging and external power supply, a battery electric vehicle (BEV), and a gasoline engine vehicle. Here, as shown in FIG. 1, an example applied to a hybrid vehicle in which an engine 3 and a vehicle driving motor 4 are provided together is shown. Note that the vehicle 2 shown in FIG. 1 is merely an example.

[0018] This brake device 1 includes a brake booster 5, a drive shaft negative pressure pump 6, and a driving force transmission unit 7.

[0019] The brake booster 5 has a function of assisting a driver's braking force generated by depressing a brake pedal 8. The inside of the brake booster 5 is in a negative pressure state, and the driver's braking force is assisted by the pressure difference between the negative pressure and the atmospheric pressure. The brake booster 5 is connected to the drive shaft negative pressure pump 6 via a negative pressure hose 9, and is also connected to a brake body 11 (e.g., a disc brake) provided on a wheel 10 via a hydraulic hose 12. A hydraulic pressure control unit 13 is provided in the hydraulic hose 12. By controlling the hydraulic pressure sent to the brake body 11 by the hydraulic pressure control unit 13, safety functions such as an anti-lock brake system, a traction control system, and a skid prevention system can be exerted.

[0020] The drive shaft vacuum pump 6 has a pumping function that creates a negative pressure inside the brake booster 5. The drive shaft vacuum pump 6 is mounted on the transaxle 14, which receives driving force from the engine 3 and the vehicle drive motor 4. The transaxle 14 is a gear mechanism that integrates the functions of a transmission and a differential gear. The drive shaft 15 (see Figure 2) of the transaxle 14 is connected to the wheels 10 via a drive shaft 16, and the vehicle 2 moves using the driving force from the drive shaft 15.

[0021] A drive force transmission unit 7 is provided between the drive shaft 15 of the transaxle 14 and the drive shaft vacuum pump 6. The drive force transmission unit 7 has the function of transmitting a portion of the driving force transmitted to the drive shaft 15, which is used to move the vehicle 2, to the drive shaft vacuum pump 6.

[0022] As shown in Figure 2, the drive force transmission unit 7 includes a first gear 17 provided on the drive shaft 15, a second gear 19 provided on the rotating shaft 18 of the drive shaft vacuum pump 6, and a chain 20 provided across the first gear 17 and the second gear 19. The second gear 19 incorporates a clutch 21 that can be switched between a disconnected state, where the transmission of drive force between the drive shaft 15 and the drive shaft vacuum pump 6 is interrupted, and a transmitted state, where drive force is transmitted. The position of the clutch 21 is not particularly limited; it can be built into the first gear 17, or it may be provided between the drive shaft 15 and the first gear 17, or between the rotating shaft 18 and the second gear 19, rather than being built into the first gear 17 or the second gear 19. In addition, instead of the chain 20, a rubber belt or a combination of multiple gears can be used to transmit drive force from the drive shaft 15 to the drive shaft vacuum pump 6.

[0023] The brake booster 5 is connected to the engine 3 and the electric vacuum pump 22 by a vacuum hose 9. When the engine 3 is operating, the intake manifold becomes a negative pressure zone. This negative pressure can create a negative pressure state inside the brake booster 5. Alternatively, the electric vacuum pump 22 can be operated using electricity supplied from the battery 23 to create a negative pressure state inside the brake booster 5. In other words, in a hybrid vehicle, the negative pressure in the brake booster 5 can be ensured by operating one or more of the drive shaft vacuum pump 6, engine 3, or electric vacuum pump 22 simultaneously.

[0024] Vehicle 2 is equipped with a battery management system 24 for detecting the charge state of the battery 23, a vehicle speed sensor 25 for measuring vehicle speed, a gradient sensor 26 for measuring the gradient of the road, a brake pedal sensor 27 for detecting the amount of brake pedal operation by the driver 8, and an accelerator pedal sensor 28 for detecting the amount of accelerator pedal operation by the driver. Data from each sensor is collected by an electronic control unit 29. Based on the collected data, the electronic control unit 29 controls the engine 3, vehicle drive motor 4, clutch 21, electric vacuum pump 22, hydraulic control unit 13, etc. Vehicle 2 is also equipped with a manual switch 30 for manually switching between the disengaged and transmitted states of the clutch 21.

[0025] The operation of the brake device 1 according to this invention will be explained according to the type of vehicle 2.

[0026] (1) In the case of electric vehicles The electric vehicle is equipped with a drive shaft vacuum pump 6 and an electric vacuum pump 22 as means for generating negative pressure in the brake booster 5. The means for generating negative pressure can be switched as appropriate according to the driving state of the vehicle 2 shown in Figure 3 (acceleration, steady driving, deceleration, and stopping). During acceleration and steady driving, the electric vacuum pump 22 is operated to prevent a decrease in acceleration and driving performance due to the distribution of the driving force of the drive shaft 15 to the drive shaft vacuum pump 6. On the other hand, during deceleration, the drive shaft vacuum pump 6 is operated to prevent the electric vacuum pump 22 from consuming power from the battery 23. When the vehicle is stopped, since driving force cannot be obtained from the drive shaft 15, the electric vacuum pump 22 is operated as needed. When the electric vacuum pump 22 is operated, that is, when the drive shaft vacuum pump 6 is not operated, the clutch 21 is disengaged. In case of emergency, the electric vacuum pump 22 is operated to ensure negative pressure in the brake booster 5.

[0027] Even under the conditions under which the drive shaft vacuum pump 6 is deemed to be activated (when the vehicle 2 is decelerating), the operating state of the drive shaft vacuum pump 6 can be optimized by controlling the clutch 21.

[0028] For example, when the brake pedal sensor 27 detects that the brake pedal 8 has been operated, when the accelerator pedal sensor 28 detects that the amount of accelerator pedal operation is 5% or less, or when the gradient sensor 26 detects that the road gradient is -2% or less (downhill), the clutch 21 can be put into a transmission state and the drive shaft vacuum pump 6 can be activated when at least one of these conditions (or two or more conditions) is met.

[0029] When the accelerator pedal is pressed by 5% or less, it is assumed that the driver does not intend to accelerate, and on downhill slopes of -2% or less, the vehicle speed is almost maintained even when the drive shaft vacuum pump 6 is activated, so in either case, a decrease in drivability is unlikely.

[0030] On the other hand, even under conditions where the drive shaft vacuum pump 6 is deemed to be activated (when the vehicle 2 is decelerating), the clutch 21 can be disengaged and the drive shaft vacuum pump 6 can be stopped when the battery management system 24 detects that the battery 23's charge level is 50% or less, or when the vehicle speed measured by the vehicle speed sensor 25 is 15 km / h or less. By stopping the drive shaft vacuum pump 6 when the battery 23's charge level is 50% or less, the recovery of regenerative power can be prioritized. Also, by stopping the drive shaft vacuum pump 6 when the vehicle speed is 15 km / h or less, it is possible to prevent the vehicle 1 from rapidly decelerating just before coming to a stop due to pump resistance. Furthermore, the driver can operate the manual switch 30 to disengage the clutch 21, allowing the vehicle 2 to coast.

[0031] Furthermore, when the battery 23 is nearly fully charged (for example, when the charge level is 85% or higher), the clutch 21 is kept in the transmission state down to a lower vehicle speed range (for example, 5 km / h), and the drive shaft vacuum pump 6 is operated, thereby reducing the braking load on the brake body 11. In addition, the need for discharge countermeasures by the vehicle drive motor 4 to prevent overcharging is eliminated, and power consumption can be reduced. Moreover, even when the battery 23 is nearly fully charged, the driver can operate the manual switch 30 to disengage the clutch 21, allowing the vehicle 2 to coast.

[0032] (2) In the case of hybrid vehicles and plug-in hybrid vehicles (when driving using the vehicle drive motor 4) Hybrid vehicles and plug-in hybrid vehicles are equipped with a drive shaft vacuum pump 6, an engine 3, and an electric vacuum pump 22 as means for forming a vacuum in the brake booster 5. The means for forming a vacuum when the vehicle is driven by the vehicle drive motor 4 is switched as appropriate according to the driving state of the vehicle 2 shown in Figure 3 (acceleration, steady driving, deceleration, and stopping). During acceleration and steady driving, the electric vacuum pump 22 is operated to prevent a decrease in acceleration and driving performance due to the distribution of the driving force of the drive shaft 15 to the drive shaft vacuum pump 6. On the other hand, during deceleration, the drive shaft vacuum pump 6 is operated to prevent the electric vacuum pump 22 from consuming power from the battery 23. When the vehicle is stopped, since driving force cannot be obtained from the drive shaft 15, the electric vacuum pump 22 is operated. In case of emergency, the engine 3 or the electric vacuum pump 22 is operated to secure a vacuum in the brake booster 5.

[0033] Even under the conditions under which the drive shaft vacuum pump 6 is deemed to be activated (when the vehicle 2 is decelerating), the operating state of the drive shaft vacuum pump 6 can be optimized by controlling the clutch 21.

[0034] For example, when the brake pedal sensor 27 detects that the brake pedal 8 has been operated, when the accelerator pedal sensor 28 detects that the amount of accelerator pedal operation is 5% or less, or when the gradient sensor 26 detects that the road gradient is -2% or less (downhill), the clutch 21 can be put into a transmission state and the drive shaft vacuum pump 6 can be activated when at least one of these conditions (or two or more conditions) is met.

[0035] When the accelerator pedal is pressed by 5% or less, it is assumed that the driver does not intend to accelerate, and on downhill slopes of -2% or less, the vehicle speed is almost maintained even when the drive shaft vacuum pump 6 is activated, so in either case, a decrease in drivability is unlikely.

[0036] On the other hand, even under conditions where the drive shaft vacuum pump 6 is deemed to be activated (when the vehicle 2 is decelerating), the clutch 21 can be disengaged and the drive shaft vacuum pump 6 can be stopped when the battery management system 24 detects that the battery 23's charge level is 50% or less, or when the vehicle speed measured by the vehicle speed sensor 25 is 15 km / h or less. By stopping the drive shaft vacuum pump 6 when the battery 23's charge level is 50% or less, the recovery of regenerative power can be prioritized. Also, by stopping the drive shaft vacuum pump 6 when the vehicle speed is 15 km / h or less, it is possible to prevent the vehicle 1 from rapidly decelerating just before coming to a stop due to pump resistance. Furthermore, the driver can operate the manual switch 30 to disengage the clutch 21, allowing the vehicle 2 to coast.

[0037] Furthermore, when the battery 23 is nearly fully charged (for example, when the charge level is 85% or higher), the clutch 21 is kept in the transmission state down to a lower vehicle speed range (for example, 5 km / h), and the drive shaft vacuum pump 6 is operated, thereby reducing the braking load on the brake body 11. In addition, the need for discharge countermeasures by the vehicle drive motor 4 to prevent overcharging is eliminated, and power consumption can be reduced. Moreover, even when the battery 23 is nearly fully charged, the driver can operate the manual switch 30 to disengage the clutch 21, allowing the vehicle 2 to coast.

[0038] (3) In the case of hybrid vehicles and plug-in hybrid vehicles (when running on engine 3) The means of generating negative pressure during driving by engine 3 is switched as appropriate according to the driving state of vehicle 2 (acceleration, steady driving, deceleration, and stopping) as shown in Figure 3. During acceleration and steady driving, the negative pressure in the intake manifold of engine 3 creates a negative pressure state in the brake booster 5. On the other hand, during deceleration, the drive shaft negative pressure pump 6 is operated. When stopped, since driving force cannot be obtained from the drive shaft 15, negative pressure is generated by the operation of engine 3 or the electric negative pressure pump 22. In case of emergency, engine 3 or the electric negative pressure pump 22 is operated to ensure negative pressure in the brake booster 5.

[0039] Even under the conditions under which the drive shaft vacuum pump 6 is deemed to be activated (when the vehicle 2 is decelerating), the operating state of the drive shaft vacuum pump 6 can be optimized by controlling the clutch 21.

[0040] For example, when the brake pedal sensor 27 detects that the brake pedal 8 has been operated, when the accelerator pedal sensor 28 detects that the amount of accelerator pedal operation is 5% or less, or when the gradient sensor 26 detects that the road gradient is -2% or less (downhill), the clutch 21 can be put into a transmission state and the drive shaft vacuum pump 6 can be activated when at least one of these conditions (or two or more conditions) is met.

[0041] When the accelerator pedal is pressed by 5% or less, it is assumed that the driver does not intend to accelerate, and on a downhill slope of -2% or less, the vehicle speed is almost maintained even when the drive shaft vacuum pump 6 is activated, so in either case, a decrease in drivability is unlikely to occur. In addition, in hybrid vehicles and plug-in hybrid vehicles, the engine 3 may be controlled to stop when the above conditions relating to the brake pedal 8, accelerator pedal, and road gradient are met. In this case, a vacuum is generated by activating the electric vacuum pump 22.

[0042] On the other hand, even under conditions where the drive shaft vacuum pump 6 is deemed to be activated (when the vehicle 2 is decelerating), the clutch 21 can be disengaged and the drive shaft vacuum pump 6 can be stopped when the battery management system 24 detects that the battery 23's charge level is 50% or less, or when the vehicle speed measured by the vehicle speed sensor 25 is 15 km / h or less. By stopping the drive shaft vacuum pump 6 when the battery 23's charge level is 50% or less, the recovery of regenerative power can be prioritized. Also, by stopping the drive shaft vacuum pump 6 when the vehicle speed is 15 km / h or less, it is possible to prevent the vehicle 1 from rapidly decelerating just before coming to a stop due to pump resistance. Furthermore, the driver can operate the manual switch 30 to disengage the clutch 21, allowing the vehicle 2 to coast.

[0043] In the brake device 1 according to this invention, the driving force for driving the vehicle 2 transmitted to the drive shaft 15 is transmitted to the drive shaft vacuum pump 6 by the drive force transmission unit 7, and the drive shaft vacuum pump 6 creates a negative pressure state inside the brake booster 5. Therefore, even if control is performed to stop the engine 3 while driving in a hybrid vehicle, for example, it is possible to appropriately secure the negative pressure necessary to operate the brake booster 5 while the vehicle 2 is in motion.

[0044] Furthermore, the brake device 1 according to this invention is provided with a clutch 21 that switches between a disconnected state in which the transmission of driving force between the drive shaft 15 and the drive shaft vacuum pump 6 is interrupted, and a transmitted state in which driving force is transmitted. By disengaging the clutch 21 during acceleration or steady-state driving, it is possible to prevent the drive shaft vacuum pump 6 from becoming a rotational resistance to the drive shaft 15, thereby reducing drivability and fuel efficiency (electricity consumption). Also, by transmitting the clutch 21 during deceleration, the negative pressure state of the brake booster 5 can be ensured, and the braking load on the brake body 11 can be reduced by the pump resistance of the drive shaft vacuum pump 6.

[0045] Furthermore, in the brake device 1 according to this invention, the clutch 21 is disengaged when a vehicle speed below a predetermined vehicle speed (for example, 15 km / h) is detected during deceleration, thereby preventing the vehicle 1 from rapidly decelerating just before coming to a stop due to the pump resistance of the drive shaft vacuum pump 6.

[0046] Furthermore, in the brake device 1 according to this invention, when the charge level of the battery 23 exceeds a predetermined charge level, the predetermined vehicle speed (for example, 15 km / h) is reduced to a lower speed (for example, 5 km / h), thereby reducing the braking load on the brake body 11. In addition, the need for discharge countermeasures in the vehicle drive motor 4 to prevent overcharging is eliminated, and power consumption can be reduced.

[0047] Furthermore, in the brake device 1 according to this invention, the clutch 21 is disengaged when a gradient sensor 26 detects a gradient of -2% or more, so that the drive shaft vacuum pump 6 does not easily affect the vehicle speed and a decrease in drivability can be prevented.

[0048] Furthermore, in the brake device 1 according to this invention, the clutch 21 is disengaged when the charge level of the battery 23 is below a predetermined charge level, so that the recovery of regenerative power can be prioritized over the generation of negative pressure by the drive shaft negative pressure pump 6.

[0049] Furthermore, in the brake device 1 according to this invention, a manual switch 30 is provided so that the clutch 21 can be manually switched between the disengaged state and the transmission state, thus meeting the driver's desire to coast the vehicle 2.

[0050] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Accordingly, the scope of the invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0051] 1. Brake system 2 vehicles 3 Engines 4. Motor for vehicle drive 5. Brake booster 6. Drive shaft vacuum pump 7. Power transmission section 8. Brake pedal 9. Vacuum hose 10 wheels 11 Brake body 12 Hydraulic hoses 13. Hydraulic Control Unit 14 transaxle 15 Drive shaft 16 drive shafts 17 First Gear 18 rotation axes 19 Second Gear 20 chain 21 Clutch 22 Electric vacuum pump 23 batteries 24 Battery Management System 25. Vehicle speed sensor 26 Gradient Sensor 27 Brake pedal sensor 28. Accelerator pedal sensor 29 Electronic control unit 30 Manual switch

Claims

1. A brake booster that uses negative pressure to assist the driver's braking force, A drive shaft vacuum pump that creates a negative pressure state inside the brake booster, A drive force transmission unit that transmits the driving force transmitted to the drive shaft to the drive shaft vacuum pump for driving the vehicle, A braking device having the following features.

2. The brake device according to claim 1, further comprising a clutch that switches between a disconnected state in which the transmission of driving force between the drive shaft and the drive shaft vacuum pump is interrupted and a transmitted state in which driving force is transmitted.

3. It further includes a vehicle speed sensor that measures vehicle speed, The brake device according to claim 2, wherein the clutch is disengaged when the vehicle speed sensor detects acceleration or constant speed driving of the vehicle, and the clutch is transmitted when the vehicle deceleration is detected.

4. The brake device according to claim 3, which is controlled to disengage the clutch when a vehicle speed below a predetermined vehicle speed is detected during deceleration.

5. The vehicle further comprises a drive motor for propelling the vehicle and a battery for supplying power to the drive motor, The brake device according to claim 4, wherein the predetermined vehicle speed is reduced to a lower speed when the charge level of the battery is equal to or greater than a predetermined charge level.

6. It further includes a gradient sensor for measuring the road gradient, The brake device according to claim 2, which is controlled to disengage the clutch when a gradient greater than a predetermined gradient is detected.

7. The vehicle further comprises a drive motor for propelling the vehicle and a battery for supplying power to the drive motor, The brake device according to claim 2, wherein the clutch is controlled to be in a disengaged state when the charge level of the battery is less than or equal to a predetermined charge level.

8. The brake device according to any one of claims 2 to 7, which allows the clutch to be manually switched between a disengaged state and a transmission state.

Images