Separated type electric brake booster

Abstract

To provide an improved electric brake booster in which when operating motor brake, a pedal stepping force transmission element and a brake pedal are not interlocked since a brake assist force transmission line of the brake pedal is separated from the pedal stepping force transmission element.SOLUTION: A vehicle electric brake booster includes: a pedal stepping force transmission mechanism which is driven by a brake pedal to move in an axial direction; a detector for detecting operation of the pedal stepping force transmission mechanism; a brake motor which generates brake assist force by execution of a motor brake operation; and an assist force transmission mechanism which is driven by the brake motor to move in an axial direction, thereby transmitting brake assist force generated by the brake motor to a piston of a brake master cylinder. In a motor brake operation mode, the assist force transmission mechanism is kinematically separated from the pedal stepping force transmission mechanism, and further, input of the electric brake booster is configured by only brake assist force generated by the brake motor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present application relates to an electric brake booster for use in a vehicle brake system, in which a brake motor has an independent brake assist force transmission line that is separate from the pedal depression force transmission line. [Background technology]

[0002] Many vehicles are equipped with a brake booster in their hydraulic brake system. Brake boosters are usually classified into vacuum boosters and electric boosters. Vacuum boosters use the vacuum in the engine's intake pipe as a brake assist source, while electric boosters use a motor as a brake assist source.

[0003] In a conventional electric booster, the brake assist force and the pedal depression force are usually transmitted to the piston of the brake master cylinder via a transmission line connected thereto, i.e., a commonly used force transmission element. When a driver applies a brake force to such an electric booster, the motor of the electric booster generates a brake assist force, and the pedal depression force and the brake assist force are combined and transmitted to the piston of the brake master cylinder. When a vehicle equipped with an automatic braking function (e.g., an automatic driving or active braking module, etc.) automatically applies the brakes, the motor of the electric booster actively generates a brake assist force without the need for driver intervention (i.e., no pedal depression force is input). However, when the brake assist force generated by the motor is transmitted to the piston of the brake master cylinder, the pedal depression force transmission element also works in conjunction, and in some cases, even the brake pedal works in conjunction. This not only affects the transmission efficiency of the brake assist force, but may also cause discomfort to the driver who has his / her foot on the brake pedal. Summary of the Invention [Problem to be solved by the invention]

[0004] The gist of the present application is to provide an improved electric brake booster device in which, when performing a motor braking operation, the braking assist force transmission line of the brake motor is separated from the pedal effort transmission element, so that the pedal effort transmission element and the brake pedal are not interlocked.

Means for Solving the Problems

[0005] Therefore, according to one aspect of the present application, there is provided a separable electric brake booster device used in a vehicle brake system, including a pedal effort transmission mechanism that is driven by a brake pedal and is suitably arranged to move in the axial direction, a detection device arranged to detect the operation of the pedal effort transmission mechanism, a brake motor suitably arranged to generate a braking assist force by executing a motor braking operation, and an assist force transmission mechanism that is driven by the brake motor and moves in the axial direction to transmit the braking assist force generated by the brake motor to the piston of the brake master cylinder. In the motor braking operation, the assist force transmission mechanism is kinematically separated from the pedal effort transmission mechanism, and moreover, the input of the electric brake booster device is constituted only by the braking assist force generated by the brake motor.

Effects of the Invention

[0006] According to the present application, when performing a motor braking operation, the braking assist force transmission line of the brake motor of the electric brake booster device is separated from the pedal effort transmission line. Since the operation of the braking assist force transmission element does not interlock the pedal effort transmission element and the brake pedal, it is possible to avoid giving the driver an uncomfortable feeling from the brake pedal. Also, when the brake motor operates, the input of the electric brake booster device is only from the brake motor and is not combined with the pedal effort.

[0007] The separable electric brake booster device of the present application can be replaced with a conventional vacuum booster device.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0009] Hereinafter, with reference to the drawings, a plurality of possible embodiments of the present application will be described. It should be pointed out that the drawings are merely for representing the principles of the present application and do not represent the actual structure of the present application. Therefore, the drawings are not drawn according to a ratio. Moreover, for clarity, some detailed parts are deformed or omitted.

[0010] First, it should be pointed out that in the present application, the "rear side" is the side closer to the brake pedal of the vehicle in terms of kinematics, and the "front side" is the side away from the brake pedal in terms of kinematics, that is, the side closer to the brake master cylinder.

Example

[0011] As shown in FIGS. 1 and 2, the separable electric brake booster device used in the vehicle brake system in a possible embodiment according to the present application is used to transmit the output to the piston 2 of the brake master cylinder 1 of the vehicle hydraulic brake system. For the details of a part of the structure of the electric brake booster device, refer to FIGS. 3 to 10. FIGS. 1 and 2 show the initial position (non-operating state) of the electric brake booster device.

[0012] The piston 2 is axially movable relative to the cylinder body of the brake master cylinder 1. Since the brake master cylinder 1 and its piston 2 of the vehicle hydraulic brake system are ordinary in this field, no detailed description will be given. It should be pointed out that the brake master cylinder 1 has a dual piston, and the piston 2 represented in the figure is the piston of the rear chamber (first chamber) of the brake master cylinder 1, and moreover, the brake master cylinder 1 further includes a front chamber (second chamber) piston not shown in the figure.

[0013] The electric brake booster device of the present application is associated with the brake pedal side pusher 3 and includes a brake motor 4 for generating a braking assist force. The electric brake booster device further includes a control means 5 and a pedal stroke sensor 6. The pedal stroke sensor 6 detects the stroke of the pusher 3, that is, it is used to detect the stroke of the brake pedal. The control means 5 receives the brake pedal stroke signal detected by the pedal stroke sensor 6 and can control the operation of the brake motor 4. After receiving the braking signal, the control means 5 starts the brake motor 4 to generate a brake hydraulic pressure. The braking signal may be a brake pedal stroke signal or a braking signal from the vehicle automatic braking function.

[0014] When braking is performed using the brake motor 4, only the braking assist force generated by the brake motor 4 is used as the input to the electric brake booster device, and the pedal force of the brake pedal is not included in the input. When braking is performed without using the brake motor 4, for example, when the brake motor 4 is not powered or the brake motor 4 is disabled, the pedal force input by the driver through the brake pedal via the pusher 3 can be used as the input to the electric brake booster device.

[0015] The electric brake booster further includes a drive sleeve 11 and a drive nut 12, both of which are arranged coaxially with the piston 2, and moreover, this defines the central axis of the electric brake booster. The drive sleeve 11 is arranged in the drive nut 12, and there is a screw drive engagement between the two. The drive nut 12 is rotatably arranged in a booster housing (not shown) via a bearing 13 (and there may be other bearings). The brake motor 4 drives the rotation of the drive nut 12 via a corresponding drive mechanism (such as a gear set). According to a possible embodiment, when the brake motor 4 is energized (the rotor of the motor rotates or is stationary), the brake motor 4 locks the axial position of the drive nut 12 by a drive mechanism (especially a gear set) between the drive nut 12, so that the drive nut 12 cannot move axially. When the brake motor 4 is not energized, since the rotor of the motor is rotatable, the brake motor 4 releases the axial movement lock function of the drive nut 12, and the drive nut 12 can move axially.

[0016] Alternatively, a single locking structure may be arranged. When the brake motor 4 is energized, since the locking structure locks the drive nut 12 axially, the drive nut 12 does not have the ability to move axially. On the other hand, when the brake motor 4 is not energized, the locking structure releases the axial movement lock of the drive nut 12 and enables the drive nut 12 to move axially.

[0017] When the drive nut 12 is axially locked, the rotation of the drive nut 12 can push the drive sleeve 11 to move axially within the drive nut 12.

[0018] Refer to FIG. 5. The drive nut 12 is generally cylindrical, and a part of its axial direction is a threaded part 12a, which is provided with an inward-facing thread, and this thread is used to mesh with the external thread of the drive sleeve 11 (the drive sleeve 11 is provided with an external thread over its entire length). Also, the threaded part 12a divides the inner hole of the drive nut 12 into a front part 12b and a rear part 12c. The axial length of the threaded part 12a is about 1 / 3 or less of the axial length of the drive nut 12. It is preferable that the axial length of the front part 12b is shorter than that of the rear part 12c.

[0019] Returning to FIGS. 1 and 2, a plunger 14 is disposed between the drive sleeve 11 and the piston 2. The driving force generated by the brake motor 4, that is, the braking assist force, is transmitted to the drive sleeve 11 via the drive nut 12, and further transmitted from the drive sleeve 11 to the piston 3 via the plunger 14. The plunger 14 is in direct contact with the piston 2, and the plunger 14 can directly transmit the braking assist force to the piston 2. Or, since a force transmission element (such as a push rod) can be disposed between the plunger 14 and the piston 2, the plunger 14 can transmit the braking assist force to the piston 2 via the force transmission element. The arrangement of such a force transmission element can advantageously distribute the braking assist force on the piston 2 and the like.

[0020] Refer to FIG. 6. The plunger 14 generally has a cylindrical main body 14a, and a pair of flanges 14b extending in opposite radial directions are formed at the front end of the main body 14a. The diameter of the rear part of the main body 14a is reduced to form a small-diameter part 14c. Also, in the main body 14a, a radial through-hole (inner chamber) 14d penetrating the main body 14a is formed along the radial direction perpendicular to the radial direction in which the flange 14b extends. The front end of the radial through-hole 14d ends at a location near the front end face of the main body 14a, and the rear end of the radial through-hole 14d communicates with the rear end face of the main body 14a through an axial through-hole 14e. A front end wall 14f exists between the front end of the radial through-hole 14d and the front end face of the main body 14a.

[0021] The front end of the push rod 15 is connected to the pedal spring 16. By including a combined spring formed by stacking leaf springs, the pedal spring 16 can have its spring hardness in the axial direction gradually increased from the longitudinal (radial) outer end towards the radial center. For example, referring to FIG. 7. The pedal spring 16 includes leaf springs 16a, 16b, 16c stacked in order axially. From the front side to the rear side in the axial direction, the radial size of each leaf spring gradually decreases.

[0022] Returning to FIGS. 1 and 2. The front end of the plunger 14 is arranged to be suitable for abutting (directly or indirectly) against the piston 2. The small-diameter portion 14c of the plunger 14 is inserted into the front portion 12b of the drive nut 12, making the plunger 14 axially movable relative to the drive nut 12.

[0023] The push rod 15 is disposed in the axially penetrating hole defined by the drive sleeve 11. The front portion of the pusher 3 is connected to the push rod 15. The front end of the push rod 15 extends from the front end of the drive sleeve 11, passes through the axially penetrating hole 14e of the plunger 14, and is inserted into the radially penetrating hole 14d. The front end of the push rod 15 is further connected to the reaction plate 17 on the front side of the pedal spring 16. The pedal spring 16 and the reaction plate 17 pass through the radially penetrating hole 14d of the plunger 14 and are exposed from both radial sides of the plunger 14. In the initial position, the reaction plate 17 is located on the axially rear side of the front end wall 14f of the plunger 14 and is axially spaced from the front end wall 14f.

[0024] Both radial ends of the pedal spring 16 are respectively connected to the regulating rod 18. The regulating rod 18 extends parallel to the central axis of the force multiplying device and is constrained by a regulating plate 19 disposed so as to surround the small-diameter portion 14c of the plunger 14, and the regulating rod 18 can reciprocate relative to the regulating plate 19 within a finite axial distance. In the example shown in FIG. 8, the front end of the regulating rod 18 is fixed to the longitudinal outer end of the pedal spring 16, and a thin rod portion 18a is formed at the rear portion of the regulating rod 18. The thin rod portion 18a is inserted into a through hole 19a in the corresponding radial end of the regulating plate 19 shown in FIG. 9 and is axially movable within the through hole 19a. When the pedal spring 16 is elastically deformed axially by the pushing of the push rod 15, the axial movement range of the regulating rod 18 is limited by the contact between the large-diameter portions at both axial ends of the thin rod portion 18a and the axial end faces on both sides of the regulating plate 19, that is, the axial movement range of both radial ends of the pedal spring 16 is limited. Therefore, the regulating rod 18 and the regulating plate 19 constitute a regulating structure for the pedal spring 16.

[0025] It is understood that other forms of pedal spring regulating elements can also be adopted. For example, FIG. 10 shows other types of regulating structures of the pedal spring 16. Among them, the front end of the regulating rod 18 is hinge-connected to the longitudinal outer end of the pedal spring 16, and the rear end of the regulating rod 18 has a hinge pin, and the hinge pin is inserted into a guide groove 19a extending parallel to the axial direction in the regulating plate 19, and the hinge pin is movable back and forth in the guide groove 19a. In the initial position, the radial distance between the front ends of the two regulating rods 18 and the radial distance between the rear ends of the two regulating rods 18 may be different or the same. When the push rod 15 pushes the pedal spring 16 forward, the hinge pin at the rear end of the regulating rod 18 slides forward in the guide groove 19a. When the hinge pin at the rear end of the regulating rod 18 reaches the front groove bottom of the guide groove 19a, the rear end of the regulating rod 18 is restrained and cannot continue to move forward. Therefore, both radial ends of the pedal spring 16 cannot move further forward. As the push rod 15 pushes the central portion of the pedal spring 16 forward, the pedal spring 16 begins to elastically deform axially.

[0026] The regulating plate 19 is non-rotatable and is held so that its axial position relative to the drive nut 12 does not change. In other words, the regulating plate 19 is axially movable with the drive nut 12 but non-rotatable. An appropriate holding structure can realize the above-described ability of the regulating plate 19. For example, in the illustrated example, the regulating plate 19 is fixed to the outer ring of the bearing 13.

[0027] Spring retainers 20 for pressing the first return spring 21 are mounted on the front sides of both radial ends of the reaction plate 17. The first return spring 21 is used to axially press the push rod 15 backward via the spring retainer 20, the reaction plate 17, and the pedal spring 16. The first return spring 21 can be mounted between the cylinder body of the brake master cylinder 1 and the spring retainer 20.

[0028] Also, a second return spring 22 for axially pressing the plunger 14 rearward is mounted between the cylinder body of the brake master cylinder 1 and the flange 14b of the plunger 14. The spring hardness of the second return spring 22 is higher than that of the first return spring 21.

[0029] It can be understood that according to the internal structure of the power amplifier, the first return spring 21 and the second return spring 22 can be arranged at other positions. Also, in the illustrated example, both are in the form of coil compression springs, but other forms of springs may be adopted as long as the above pressing functions of both can be realized. For example, in the example shown in FIG. 10, the first return spring 21 is a 3D metal wire spring, one end of which is hooked to the longitudinal outer end of the pedal spring 16, and the other end is fixed to the restricting plate 19. It can be understood that the second return spring 22 may also adopt the form of a 3D metal wire spring.

[0030] FIG. 3 schematically depicts the pedal force transmission mechanism (line) in the electric brake power amplifier. Among them, the pedal force is transmitted to the pedal spring 16 and the reaction plate 17 via the pusher 3 and the push rod 15, and the pedal spring 16 and the reaction plate 17 can be moved forward against the first return spring 21. A radially extending portion 17a is mounted or formed at one radially extending end of the reaction plate 17. The radially extending portion 17a faces the pedal stroke sensor 6, and since the axial movement of the radially extending portion 17a can be detected by the pedal stroke sensor 6 (for example, by a changing magnetic field), the control means 5 can determine the pedal stroke and can also judge the driver's intention to brake.

[0031] Figure 4 schematically depicts the braking assist force transmission mechanism (line) in the electric brake booster device. Among these, the driving force (braking assist force) of the brake motor 4 is transmitted to the plunger 14 via the drive nut 12 and the drive sleeve 11. Therefore, while resisting the thrust of the second return spring 22, the plunger 14 is moved forward, and the plunger 14 transmits the braking assist force generated by the brake motor 4 to the piston 2 as the output of the electric brake booster device.

[0032] It should be pointed out that in the illustrated example, the braking assist force is mainly transmitted via the drive nut 12 and the drive sleeve 11. However, it can be understood that other mechanisms for converting rotational motion into linear motion, such as a gear-rack mechanism, etc., can be used here to transmit the braking assist force.

[0033] Also, it should be pointed out that the plunger 14, the push rod 15, the pedal spring 16, and the reaction plate 17 are only allowed axial movement and rotation is not allowed. The prevention of their rotation can be realized by an appropriate restraint structure. For example, it is realized by the rotation prevention restraint generated by the restraint rod 18 against the pedal spring 16 via the restraint plate 19 (non-rotatable).

[0034] The operation of the electric brake booster device will be described below.

[0035] First, describe the normal operation mode of the electric brake booster device. The so-called normal operation means that the electric brake booster device is activated by the driver stepping on the brake pedal, and the brake motor 4 provides a braking assist force. As shown in Fig. 11, after the driver steps on the brake pedal, the pusher 3 axially pushes the pedal spring 16 and the reaction plate 17 forward by the idle stroke amount via the push rod 15. The distance of this idle stroke is determined by the regulation of the regulating rod 18 with respect to the regulating plate 19. For example, this idle stroke is about 5 mm or less. The control means 5 detects the idle stroke by the pedal stroke sensor 6, thereby confirming that the driver has stepped on the brake pedal, and then activates the brake motor 4 to rotate forward and drives it to move the plunger 14 forward by a determined distance. The forward movement of the plunger 14 at this part moves the piston 2 forward into the cylinder body of the brake master cylinder 1, and the pressure in the cylinder body of the brake master cylinder 1 begins to rise.

[0036] After the idle stroke ends, if the driver further depresses the brake pedal, due to the restriction received by the restriction rod 18 and the restriction plate 19, it cannot continue to move. Both ends of the pedal spring 16 are also restricted by the restriction rod 18 and cannot move forward in the axial direction. The pedal spring 16 begins to deform axially. As shown in FIG. 12, the pedal spring 16 generates an increasingly larger reaction force transmitted to the brake pedal. At the same time, the reaction plate 17 moves further forward. The control means 5 detects this further forward movement by the pedal stroke sensor 6 and thereby determines the driver's intention to apply the brake. Thus, the brake motor 4 is controlled to rotate forward and move the plunger 14 forward by a determined distance. This forward movement of the plunger 14 at this part causes the piston 2 to move further forward into the cylinder body of the brake master cylinder 1, so that the brake hydraulic pressure of the brake master cylinder 1 suddenly increases, that is, the pressure surges. Since the brake master cylinder 1 outputs brake fluid with a gradually increasing pressure towards the brake elements of the brake system, the vehicle will be braked. Then, it shifts to the assist stage. At this stage, due to the pressure - force curve between the output pressure of the brake master cylinder 1 and the assist force of the booster device having a high gradient, the non - output pressure surges.

[0037] When braking ends, the driver releases the brake pedal. Due to the hydraulic pressure in the brake master cylinder 1 and the pushing of the first return spring 21, the reaction plate 17 moves backward. The control means 5 determines the driver's intention to end braking based on this. By driving the reverse rotation of the brake motor 4, the drive sleeve 11 returns to the initial position, and the reaction plate 17, the pedal spring 16, and the push rod 15 return to the initial position under the action of the first return spring 21. The plunger 14 also returns to the initial position under the action of the second return spring 22.

[0038] In the normal operation mode of the electric brake booster device of the present application, on the one hand, since the assist force curve provided by the booster device is similar to that of the conventional vacuum booster device, it can replace the vacuum booster device and provide a similar assist function. On the other hand, the reaction force and stroke of the pedal felt by the driver on the brake pedal are similar to the reaction force and stroke during the operation of the conventional brake pedal.

[0039] Subsequently, the full-electric operation mode of the electric brake booster device will be described. The so-called full-electric operation mode means that when the driver does not step on the brake pedal, the control means 5 activates the electric brake booster device based on the braking signal from the vehicle automatic braking function, or the vehicle automatic braking function directly controls the electric brake booster device. In this case, the push rod 15, the pedal spring 16, and the reaction plate 17 are held so as not to move, and the brake motor 4 rotates forward to drive the drive nut 12 and the drive sleeve 11 to drive the forward movement of the plunger 14, thereby pressing the piston 2 forward to realize the braking of the vehicle. When the braking is confirmed to be completed, the brake motor 4 is controlled to rotate reversely to return the drive sleeve 11 to the initial position, and the plunger 14 also returns to the initial position by the action of the second return spring 22.

[0040] Regardless of whether it is the normal operation mode or the full-electric operation mode, the input of the electric brake booster device is only from the brake motor 4 and there is no pedal stepping force component. Therefore, these two types of braking modes can be collectively referred to as motor braking operations. Moreover, regardless of whether it is the normal operation mode or the full-electric operation mode, it is possible to provide an assist force ratio and an assist force curve similar to those of the conventional vacuum booster device. Also, the pedal stroke applied by the driver is only used to determine the driver's braking intention by the control means 5 during the normal operation mode. In the normal operation mode, the pedal spring 16 is deformed, and the gradually increasing reaction force is fed back to the driver's foot through the brake pedal. Therefore, the driver's braking feeling is similar to that of the conventional brake system including the conventional brake system with a vacuum booster device.

[0041] In addition, the electric brake booster device further has a full pedal operation mode. The full pedal operation mode occurs when the brake motor 4 does not operate normally or is deactivated. In this situation, power is not supplied to the brake motor 4. At this time, since the axial movement locking function of the drive nut 12 is released, axial movement is possible. When the driver depresses the brake pedal, the pusher 3 axially pushes the pedal spring 16 forward via the push rod 15 until the reaction plate 17 abuts against the front end wall 14f of the plunger 14, and by interlocking the forward movement of the plunger 14, the piston 2 is pressed forward to implement vehicle braking. In this process, the pedal spring 16 pulls the regulating plate 19 through the regulating rod 18, but the regulating plate 19 also moves forward axially together with the drive nut 12 and the drive sleeve 11. After braking is completed, the related elements return to their initial positions due to the action of the first return spring 21 and the second return spring 22.

[0042] In addition, when the electric brake booster device is applied to an electric vehicle, it further has the ability to participate in brake energy recovery. In the brake energy recovery operation, the control means 5 detects the depression of the brake pedal and controls the brake motor 4 to drive the plunger 14 to move forward by a predetermined distance.

Industrial Applicability

[0043] According to the present application, when performing a motor braking operation, the braking assist force transmission line of the brake motor of the electric brake booster device is separated from the pedal stepping force transmission line. Since the operation of the braking assist force transmission element does not interlock with the pedal stepping force transmission element and the brake pedal, it is possible to avoid inhibiting the transmission of the braking assist force and avoid giving the driver an uncomfortable feeling from the brake pedal. In addition, when the brake motor operates, the input of the electric brake booster device is only from the brake motor and is not combined with the pedal stepping force.

[0044] When the brake motor is operating normally, the pedal spring is used as an emulator for providing the driver's foot with the feeling of the feedback braking state and for determining the driver's braking intention, and the pedal force is not converted into a part of the output of the brake booster device.

[0045] The separable electric brake booster device of the present application can be completely replaced with the conventional vacuum booster device, and can provide a brake assist performance similar to that of the vacuum booster device. It should be pointed out in this regard that since the vacuum brake booster device generates a braking assist force depending on the degree of vacuum generated in the intake pipe of the engine, the operation of the vacuum brake booster device has a certain influence on the operation of the engine itself. Further, after the engine stops, the intake vacuum disappears, so that the braking assist force cannot be generated. Since the electric brake booster device of the present application does not need to rely on the degree of vacuum generated in the intake pipe of the engine, it can provide a braking assist force function regardless of whether the engine is operating or not.

[0046] In addition, the separable electric brake booster device of the present application is particularly suitable for a vehicle equipped with an automatic braking function. That is, since the automatic braking function controls the electric brake booster device and the vehicle brake system, the driver does not need to step on the brake pedal.

[0047] It should be pointed out that although the present application is described herein with reference to the description of specific embodiments, the scope of the present application is not limited to the disclosed detailed parts. Various modifications can be made to these detailed parts without departing from the basic principles of the present application.

Description of Reference Numerals

[0048] 1 Brake master cylinder 2 Piston 3 Pusher 4 Brake motor 5 Control means 6 Pedal stroke sensor 11 Drive sleeve 12 Drive nut 12a Threaded portion 12b Front portion 12c Rear portion 13 Bearing 14 Plunger 14a Body 14b Flange 14c Small-diameter portion (inner chamber) 14d Radial through-hole 14e Axial through-hole 14f Front end wall 15 Push rod 16 Pedal spring 16a, 16b, 16c Leaf spring 17 Reaction plate 17a Radially extending portion 18 Regulation rod 18a Thin rod portion 19 Regulation plate 19a Guide groove 20 Spring retainer 21 First return spring 22 Second return spring

Claims

1. A pedal tread force transmission mechanism that is driven by a brake pedal and is suitably arranged to move axially, A detection device arranged to detect the operation of the pedal tread force transmission mechanism, A brake motor (4) suitably arranged to generate a braking assist force by performing a motor braking operation, An assist force transmission mechanism that is driven by the brake motor (4) to move axially and is suitably arranged to transmit the braking assist force generated by the brake motor to the piston (2) of the brake master cylinder (1). An electric brake booster device used in a vehicle, comprising: In the motor braking operation, the assist force transmission mechanism is separated from the pedal tread force transmission mechanism, and the input of the electric brake booster device is constituted only by the braking assist force generated by the brake motor, The assist force transmission mechanism includes a drive nut (12) arranged to be driven to rotate by a brake motor, and a drive sleeve (11) that engages with the drive nut and converts the rotational motion of the drive nut into a linear motion in the axial direction, The assist force transmission mechanism further includes a plunger (14) axially disposed between the piston (2) of the brake master cylinder (1) and the drive sleeve (11), and is suitably arranged to be axially pressed forward toward the cylinder body of the brake master cylinder (1) by the drive sleeve (11). The pedal tread force transmission mechanism is A push rod (15) disposed within the drive sleeve (11) and axially slidable within the drive sleeve, with the rear portion driven by the brake pedal and the front portion extending into the inner chamber (14b) of the plunger (14), An electric brake booster device including a pedal spring (16) connected to the front portion of the push rod (15) and extending radially from the inner chamber (14d), and having the ability to elastically deform axially under the axial pressing action of the push rod (15).

2. The motor braking operation is A normal braking operation in which the brake motor (4) is started based on the operation of the pedal tread force transmission mechanism detected by the detection device, and the brake motor (4) is rotated forward to generate a braking assist force, An all-electric operation that activates the brake motor (4) based on a vehicle automatic braking module braking signal and rotates the brake motor (4) in the forward direction to generate a braking assist force, and the electric brake booster device according to claim 1.

3. The longitudinal outer end of the pedal spring (16) has a stroke that is restricted in the forward direction in the axial direction. Optionally, the restricted stroke is realized by a pedal spring restricting structure, the pedal spring restricting structure includes a restricting rod (18) and a restricting plate (19), the front end of the restricting rod (18) is connected to the longitudinal outer end of the pedal spring (16), the rear end of the restricting rod (18) is axially slidable within a finite distance with respect to the restricting plate (19), and the restricting plate (19) is fixed during the motor braking operation. The electric brake booster device according to claim 1 or 2.

4. The pedal spring (16) includes a combined spring formed by stacking leaf springs, thereby gradually increasing the spring stiffness of the pedal spring (16) in the axial direction from the longitudinal outer end toward the radial center. The electric brake booster device according to any one of claims 1 to 3.

5. The pedal force transmission mechanism further includes a reaction plate (17) attached to the front portion of the push rod (15). In the non-operating state of the electric brake booster device, there is an axial distance between the reaction plate (17) and the front end wall (14f) of the plunger (14). The electric brake booster device according to any one of claims 1 to 4.

6. A radially extending portion (17a) is provided at one radial end of the reaction plate (17), and the detection device determines the operation of the pedal force transmission mechanism by detecting the axial position of the radially extending portion (17a). The electric brake booster device according to claim 5.

7. Furthermore, it includes a first return spring (21) arranged to press the reaction plate (17) along the axial direction away from the brake master cylinder (1). The electric brake booster device according to claim 5 or 6.

8. Furthermore, it includes a second return spring (22) arranged to press the plunger (14) along the axial direction away from the brake master cylinder (1). The electric brake booster device according to any one of claims 1 to 7.

9. When the brake motor (4) is charged, the drive nut (12) is axially locked and cannot move axially, but can rotate. When the brake motor (4) is not charged, the axial lock of the drive nut (12) is released. The electric brake force multiplier device according to any one of claims 1 to 7.

10. The electric brake force multiplier device can perform a full pedal braking operation when the brake motor (4) is not charged. Among them, the assist force transmission mechanism follows the pedal force transmission mechanism and transmits the braking force from the brake pedal to the piston (2) of the brake master cylinder (1). The electric brake force multiplier device according to claim 9.

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