Electric brake booster with lock

Abstract

To provide a power transmission brake booster to be used in a vehicle.SOLUTION: The power transmission brake booster includes: a pedal effort transmission component for transmitting a pedal effort from a brake pedal; a brake motor for generating a brake auxiliary force by executing a motor brake operation; an auxiliary force transmission component for pressing a piston of a brake master cylinder in an axial direction; and an engaging lock for switching between a locked state and a lock-released state. The power transmission brake booster has a motor brake operation mode and a single pedal brake operation mode. In the motor brake operation mode, the engaging lock is in a lock-released state, and therefore, the pedal effort transmission component and the auxiliary force transmission component are kinematically separated, and only the brake auxiliary force generated by the brake motor is allowed to be transmitted to the piston of the brake master cylinder via the auxiliary force transmission component, whereas in the single pedal brake operation mode, the engaging lock is in the locked state, and therefore, the pedal effort is allowed to be transmitted to the piston of the brake master cylinder via the pedal effort transmission component, the engaging lock, and the auxiliary force transmission component.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present application relates to an electric brake booster for use in a vehicle braking system. [Background technology]

[0002] Background technology Some vehicles are equipped with an electric brake booster in addition to the hydraulic braking system, and the electric brake booster utilizes a motor as a brake assist force source. In the existing electric brake booster, the brake assist force and the pedal depression force usually have a connected transmission line, i.e., are transmitted to the brake master cylinder piston through some common force transmission parts. In such an electric brake booster, when the driver performs a braking operation, the driver depresses the brake pedal to apply the pedal depression force, and the motor of the electric brake booster generates a brake assist force, and the pedal depression force and the brake assist force are combined and transmitted to the brake master cylinder piston. In a vehicle having an automatic control function (e.g., an automatic driving or active braking module, etc.), when the vehicle automatically performs braking, the driver's intervention is not required (i.e., the pedal depression force is not input), and the motor of the electric brake booster actively generates the brake assist force. However, when the brake assist force is transmitted to the brake master cylinder piston, the pedal depression force transmission parts are affected, and even the brake pedal is affected. This affects the efficiency of transmission of the brake assist force and may also cause discomfort to the driver with his / her foot on the brake pedal. Summary of the Invention [Problem to be solved by the invention]

[0003] Summary of the Invention The present application aims to provide an improved electric brake booster, which has a motor braking operation mode and a single pedal braking operation mode, in which the motor braking operation mode uses only the braking assist force of the brake motor to brake the vehicle, and in which the single pedal braking operation mode can quickly brake the vehicle through the brake pedal. [Means for solving the problem]

[0004] Therefore, according to one aspect of the present application, there is provided an electric brake booster for use in a vehicle braking system, the electric brake booster comprising: a pedal force transmission part configured to transmit a pedal force from a brake pedal, a brake motor configured to perform a motor braking operation to generate a brake assist force, an assist force transmission part configured to axially press a piston of a brake master cylinder, and a locking lock arranged on the assist force transmission part and configured to switch between a locked state and an unlocked state, the electric brake booster having a motor braking operation mode and a single pedal braking operation mode, in which in the motor braking operation mode, the locking lock is in an unlocked state, whereby the pedal force transmission part and the assist force transmission part are kinematically separated, so that only the brake assist force generated by the brake motor is transmitted to the piston of the brake master cylinder through the assist force transmission part, and in the single pedal braking operation mode, the locking lock is in an engaged state, whereby the pedal force is transmitted to the piston of the brake master cylinder through the pedal force transmission part, the locking lock, and the assist force transmission part.

[0005] According to the present application, during motor braking operation, the lock is released, thereby separating the pedal force transmission line and the brake assist force transmission line, so that the pedal force transmission parts and the brake assist force transmission parts do not interfere with each other. When performing motor braking operation, the input of the electric brake booster is generated from the brake motor and is not combined with the pedal force. In another aspect, when performing a single pedal braking operation, the lock reduces the play of the pedal force transmission parts, so that the vehicle is quickly braked. [Brief description of the drawings]

[0006] [Figure 1] 1 is a schematic cross-sectional view of an electric brake booster according to a possible embodiment of the present application (the cross-section is taken along the central axis of the booster); [Diagram 2]1 is a schematic cross-sectional view of the electric brake booster from another direction (the cross-section is taken along the central axis of the booster in a direction perpendicular to FIG. 1 ). [Diagram 3] FIG. 2 is a schematic diagram for explaining a transmission line of a pedal depression force of the electric brake booster. [Figure 4] FIG. 2 is a schematic diagram for explaining a transmission line of a brake assist force of an electric brake booster. [Diagram 5] FIG. 2 is a schematic diagram of a drive nut and plunger of the electric brake booster. [Figure 6] FIG. 2 is a schematic diagram of a drive nut and plunger of the electric brake booster. [Figure 7] FIG. 2 is a schematic diagram of a pedal spring of the electric brake booster. [Figure 8] FIG. 2 is a schematic diagram of the components of a possible embodiment of the limiting structure of the pedal spring of the electric brake booster; [Figure 9] FIG. 2 is a schematic diagram of the components of a possible embodiment of the limiting structure of the pedal spring of the electric brake booster; [Figure 10] 5 is a schematic diagram of another possible embodiment of the limiting structure of the pedal spring of the electric brake booster; FIG. [Figure 11] FIG. 2 shows a schematic diagram of a possible embodiment of the latching lock of the electric brake booster (in the locked state). [Figure 12] FIG. 12 is a schematic diagram of the lock of FIG. 11 in an unlocked state. [Figure 13] FIG. 4 is a schematic diagram of another possible embodiment of the latching lock of the electric brake booster (in the locked state). [Figure 14] FIG. 14 is a schematic diagram of a swing arm in the lock of FIG. 13. [Figure 15] FIG. 15 is a schematic diagram of the lock of FIG. 14 in an unlocked state. [Figure 16] FIG. 4 is a schematic diagram of a further possible embodiment of the latching lock of the electric brake booster (locked state); [Figure 17] FIG. 17 is a schematic diagram of the lock of FIG. 16 in an unlocked state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, some possible embodiments of the present application will be described with reference to the drawings. Please note that the drawings are only for embodying the principles of the present application, and are not intended to show the actual structure of the present application. Therefore, the drawings are not drawn to scale, and some details are exaggerated and some details are omitted for clarity.

[0008] First, please note that in this application, the term "rear side" refers to the side kinematically closer to the vehicle's brake pedal, and the term "front side" refers to the side kinematically farther away from the brake pedal, i.e., the side closer to the brake master cylinder.

[0009] As shown in Figures 1 and 2, the electric brake booster used in a vehicle braking system according to a possible embodiment of the present application is used to transmit power to a piston 2 of a brake master cylinder 1 of a vehicle hydraulic braking system. For some structural details of the electric brake booster, please refer to Figures 3 to 10. Figures 1 and 2 show the original position (non-operated state) of the electric brake booster.

[0010] The piston 2 can move axially relative to the cylinder body of the brake master cylinder 1. The brake master cylinder 1 and its piston 2 of a vehicle hydraulic braking system are known in the art, so a detailed description will be omitted. It should be noted that the brake master cylinder 1 has a dual piston, and the illustrated piston 2 is a rear partial cavity (first cavity) piston of the brake master cylinder 1, and the brake master cylinder 1 further comprises a front cavity (second cavity) piston, which is not illustrated.

[0011] The electric brake booster of the present application corresponds to a pressing member 3 on the brake pedal side and includes a brake motor 4 for generating a brake assist force. The electric brake booster includes a control unit 5 and a pedal stroke sensor 6. The pedal stroke sensor 6 is used to detect the stroke of the pressing member 3, i.e., to detect the stroke of the brake pedal. The control unit 5 can receive a signal of the brake pedal stroke detected by the pedal stroke sensor 6 and can control the operation of the brake motor 4. After receiving the braking signal, the control unit 5 starts the brake motor 4 to generate a braking hydraulic pressure. The braking signal may further be a brake pedal stroke signal, or may be a braking signal generated by an automatic braking function of the vehicle.

[0012] When braking is performed using the brake motor 4, only the brake assist force generated by the brake motor 4 becomes the input of the electric brake booster, and this input does not include the pedal force generated by the brake pedal. When braking is performed without using the brake motor 4, for example, when electrical energy is not supplied to the brake motor 4 or when the brake motor 4 cannot be used, the pedal force input by the driver through the brake pedal via the pressing member 3 becomes the input of the electric brake booster.

[0013] The electric brake booster further comprises a transmission sleeve 11 and a drive nut 12, both of which are arranged coaxially with the piston 2 and thus define a central axis of the electric brake booster. The transmission sleeve 11 is arranged in the drive nut 12 and there is a threaded transmission fit between them. The drive nut 12 is arranged in a booster housing (not shown) so as to be rotatable through a bearing 13 (other bearings may also be present). The brake motor 4 promotes the rotation of the drive nut 12 through a corresponding transmission mechanism (for example a gear set). When the brake motor 4 is electrified, the brake motor 4 locks the axial position of the drive nut 12 with the help of the transmission mechanism (in particular a gear set) between the brake motor 4 and the drive nut 12, preventing the drive nut 12 from moving axially. When the brake motor 4 is not electrified, the motor rotor is free to rotate, so that the locking function of the brake motor 4 against the axial movement of the drive nut 12 is released and the drive nut 12 can move axially.

[0014] Alternatively, a single locking structure can be provided. When the brake motor 4 is charged, the locking structure axially locks the drive nut 12 so that the drive nut 12 has no ability to move axially. When the brake motor 4 is not charged, the locking structure unlocks the axial movement of the drive nut 12 so that the drive nut 12 can move axially.

[0015] When the drive nut 12 is axially locked, rotation of the drive nut 12 presses the transmission sleeve 11 so that it can move axially within the drive nut 12 .

[0016] 5, the drive nut 12 is generally cylindrical, and a portion of the drive nut 12 in the axial direction is a threaded portion 12a provided with an internal thread, which is used to engage with the male thread of the transmission sleeve 11 (the transmission sleeve 11 may be provided with a male thread over its entire length). The threaded portion 12a further divides the inner hole of the drive nut 12 into a front portion 12b and a rear portion 12c. The axial length of the threaded portion 12a is less than about one-third of the axial length of the drive nut 12. The axial length of the front portion 12b is preferably shorter than that of the rear portion 12c.

[0017] Returning to FIG. 1 and FIG. 2, a plunger 14 is disposed between the transmission sleeve 11 and the piston 2. A driving force generated by the brake motor 4, i.e., a braking assist force, is transmitted to the transmission sleeve 11 via the drive nut 12, and is further transmitted to the piston 2 via the plunger 14 by the transmission sleeve 11. The plunger 14 can abut against the piston 2 and directly press it, so that the plunger 14 can directly transmit the braking assist force to the piston 2. Alternatively, a force transmission part (e.g., a mandrel) may be disposed between the plunger 14 and the piston 2, so that the plunger 14 transmits the braking assist force to the piston 2 via the force transmission part. Disposing such a force transmission part can be useful for equalizing the distribution of the braking assist force on the piston 2.

[0018] 6, the plunger 14 has a front end wall 14a, a pair of flanges (projecting edges) 14b extending from opposite radial sides of the front end wall 14a in opposite radial directions, and a main body extending rearward from the outer periphery of the front end wall 14a. The main body includes a substantially cylindrical first portion 14c connected to the front end wall 14a, and a substantially cylindrical second portion 14d extending upward from a rear portion peripheral portion of the first portion 14c. A radial through hole (internal cavity) 14e is formed in the main body in a radial direction perpendicular to the radial direction in which the flanges 14b extend. The front end of the radial through hole 14e terminates at the front end wall 14a, and the rear end of the radial through hole 14e communicates with the rear end surface of the main body through an axial through hole 14f. Furthermore, at least one positioning hole 14g (two diametrically opposed holes are shown in the figure) is formed in the first portion 14c, and a protrusion 14h extending rearward is formed on the surface of the rear portion of each flange 14b.

[0019] The front end of the push rod 15 is connected to the pedal spring 16. The pedal spring 16 may include a composite spring formed by stacking leaf springs, so that the spring stiffness in the axial direction of the pedal spring 16 gradually increases from the outer end in the longitudinal direction (radial direction) toward the radial center. For example, referring to FIG. 7, the pedal spring 16 includes leaf springs 16a, 16b, and 16c stacked in sequence in the axial direction. The radial dimension of each leaf spring gradually decreases from the front side to the rear side in the axial direction.

[0020] 1 and 2, the front end of the plunger 14 is adjusted and configured to press (directly or indirectly) against the piston 2. When the front portion 12b of the drive nut 12 is inserted into the second portion 14d of the plunger 14, the plunger 14 is allowed to move axially relative to the drive nut 12.

[0021] The push rod 15 is disposed in an axial through hole defined by the transmission sleeve 11. The front end of the pressing member 3 is connected to the push rod 15. The front portion of the push rod 15 extends from the front end of the transmission sleeve 11 and is inserted from the axial through hole 14f through the plunger 14 into the radial through hole 14e. A rebound plate 17 located in front of the pedal spring 16 is further connected to the front end of the push rod 15. The pedal spring 16 and the rebound plate 17 pass through the radial through hole 14e of the plunger 14 and are exposed from both radial sides of the plunger 14. In the original position, the rebound plate 17 is located axially rearward of the front end wall 14a of the plunger 14 and is spaced a certain distance from the front end wall 14a in the axial direction.

[0022] A limiting rod 18 is connected to each of the radial ends of the pedal spring 16. The limiting rod 18 extends parallel to the central axis of the booster and is limited by a limiting plate 19 arranged to surround the second part 14d of the plunger 14, so that the limiting rod 18 can move axially only a limited distance relative to the limiting plate 19. In the example shown in Fig. 8, the front end of the limiting 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 part of the limiting rod 18. The thin rod portion 18a is inserted into a bore 19a at the radial end corresponding to the limiting plate 19 shown in Fig. 9, and can move axially in the bore 19a. When the pedal spring 16 is pushed by the push rod 15 and elastically deforms in the axial direction, the thin rod portion 18a comes into contact with the large diameter portions at both axial ends and the axial end faces of the limiting plate 19, thereby restricting the range of axial movement of the limiting rod 18, i.e., restricting the range of axial movement of both radial ends of the pedal spring 16. Thus, the limiting rod 18 and the limiting plate 19 constitute a restricting structure for the pedal spring 16.

[0023] It is understood that other forms of pedal spring limiting components may also be used. For example, FIG. 10 shows another limiting structure of the pedal spring 16, in which the front end of the limiting bar 18 is hinged to the longitudinal outer end of the pedal spring 16, and a hinge shaft is provided at the rear end of the limiting bar 18. When the hinge shaft is inserted into a guide groove 19a extending parallel to the axial direction in the limiting plate 19, the hinge shaft can move forward and backward in the guide groove 19a. In the original position, the radial distance between the front ends of the two limiting bars 18 and the radial distance between the rear ends of the limiting bars 18 may be different or the same. When the push bar 15 presses the pedal spring 16 forward, the hinge shaft at the rear end of the limiting bar 18 slides forward in the guide groove 19a. When the hinge shaft at the rear end of the limiting bar 18 reaches the bottom of the groove in the front portion of the guide groove 19a, the rear end of the limiting bar 18 is restricted and cannot continue to move forward, and as a result, both radial ends of the pedal spring 16 cannot move forward any further. When the push bar 15 presses the central portion of the pedal spring 16 forward, the pedal spring 16 begins to elastically deform in the axial direction.

[0024] The limit plate 19 cannot rotate, and the axial position between the limit plate 19 and the drive nut 12 remains unchanged. In other words, the limit plate 19 can move axially together with the drive nut 12, but cannot rotate. Through a suitable retaining structure, the limit plate 19 can achieve the above function. For example, in the illustrated example, the limit plate 19 is fixed to the outer ring of the bearing 13.

[0025] A spring compression portion 20 for pressing a first return spring 21 is attached to the front side of both radial ends of the rebound plate 17. The first return spring 21 is used to press the push rod 15 axially rearward via the spring compression portion 20, the rebound plate 17, and the pedal spring 16. The first return spring 21 may be attached between the cylinder body of the brake master cylinder 1 and the spring compression portion 20.

[0026] Furthermore, a second return spring 22 for pressing the plunger 14 axially rearward is attached between the cylinder body of the brake master cylinder 1 and the flange 14b of the plunger 14. The spring stiffness of the second return spring 22 is greater than the spring stiffness of the first return spring 21.

[0027] It will be understood that the first return spring 21 and the second return spring 22 may be arranged in other positions depending on the internal structure of the booster. Furthermore, in the illustrated example, both springs are in the form of compression coil springs, but other forms of springs may be used as long as they can achieve the above-mentioned pressing function. For example, in the example shown in FIG. 10, the first return spring 21 is a 3D wire spring, one end of which is hooked to the outer end of the pedal spring 16 in the vertical direction, and the other end of which is fixed to the limiting plate 19. It will be understood that the second return spring 22 may also be in the form of a 3D wire spring.

[0028] Furthermore, at least one locking lock 30 (two diametrically opposed ones are shown in the figures) is attached to the plunger 14. A possible structure of the locking lock 30 is shown in Fig. 2, Fig. 11 and Fig. 12. The locking lock 30 comprises an electromagnetic coil 31, which is fixed to the plunger 14 (e.g., fixed to the protruding part 14h of the plunger 14), located outside the first part 14c, and defines an insertion hole in the electromagnetic coil 31 that matches the positioning hole 14g of the plunger 14. The locking lock 30 further comprises a locking pin 32, which is made of a magnet and comprises an outer bar part 32a and an inner bar part 32b that are coaxial with each other, and a flange (flange part) 32c between the outer bar part 32a and the inner bar part 32b. The diameters of the outer bar part 32a and the inner bar part 32b may be the same or different. The outer rod portion 32a can be slidably inserted into the insertion opening of the electromagnetic coil 31, and the inner rod portion 32b can be slidably inserted into the positioning hole 14g of the plunger 14. The return compression spring 33 is disposed between the outer end of the outer rod portion 32a of the insertion opening of the electromagnetic coil 31 and the outer wall of the electromagnetic coil 31, and is used to apply a radially inward thrust to the locking pin 32. When the electromagnetic coil 31 is not energized, the compression spring 33 presses the locking pin 32 radially inward, so that the flange 32c is pressed against the outer surface of the first portion 14c. The inner end of the inner rod portion 32b extends to the radial through hole 14e of the plunger 14, and at this time, as shown in Figures 2 and 11, the locking lock 30 is in a locked state, and a part of the inner rod portion 32b faces the front side of the rebound plate 17. When the electromagnetic coil 31 is energized, the electromagnetic coil 31 generates a magnetic field, which generates a radial attractive force on the locking pin 32, which overcomes the thrust of the compression spring 33 and moves the locking pin 32 in the radial direction. Furthermore, the flange 32c presses the inner end of the electromagnetic coil 31, and the inner end of the inner rod portion 32b is compressed and enters the radial through-hole 14e of the plunger 14, and the lock lock 30 is in an unlocked state, as shown in FIG. 12, and the inner rod portion 32b is completely separated from the position facing the front side of the rebound plate 17.

[0029] It is understood that the locking lock 30 may have a number of configurations to accommodate the space around the plunger 14. For example, in a possible embodiment shown in Figs. 13 to 15, the locking lock 30 includes an electromagnetic coil 31 and is fixed to the outside of the first portion 14c of the plunger 14. The locking lock 30 further includes a locking pin 32, which is made of a magnet and is a substantially cylindrical body. One portion is slidably inserted into the insertion opening of the electromagnetic coil 31, and the other portion is slidably inserted into the positioning hole 14g of the plunger 14. The locking lock 30 further includes a swing arm 34, which has a bent or curved shape and includes a front portion 34a and a rear portion 34b that is continuous therewith. The front portion 34a forms a guide groove 34c, and a positioning pin 35 fixed to the locking pin 32 is inserted into the guide groove 34c and can slide within the guide groove 34c. The rear end of the front part 34a is supported by the pin shaft 36 at one portion of the plunger 14, and the portion faces the outer periphery of the locking pin 32. In this way, when the locking pin 32 moves in the radial direction of the booster, the positioning pin 35 swings the swing arm 34 and abuts against the outer periphery of the plunger 14 through the swing arm 34 or abuts against the inner end of the electromagnetic coil 31, thereby determining the radial position of the locking pin 32. In order to ensure that the swing arm 34 and the inner end of the electromagnetic coil 31 abut against each other, a slope 34d is formed at the portion of the front part 34a facing the electromagnetic coil 31, so that the slope 34d can come into tight contact with the inner end surface of the electromagnetic coil 31 when the locking pin 32 moves toward the electromagnetic coil 31. The return compression spring 33 is disposed between the outer end of the locking pin 32 inside the insertion opening of the electromagnetic coil 31 and the outer wall of the electromagnetic coil 31, and is used to apply a thrust to the locking pin 32 in the radially inward direction.

[0030] In another embodiment shown in Figs. 16 and 17, the locking lock 30 includes an electromagnetic coil 31 and is fixed to the outside of the first portion 14c of the plunger 14. The locking lock 30 further includes a locking pin 32, which is made of a magnet and is a substantially cylindrical body. One portion is slidably inserted into the insertion hole of the electromagnetic coil 31, and the other portion is slidably inserted into the positioning hole 14g of the plunger 14. The locking lock 30 further includes a leaf spring 37 and a grooved member 38. The grooved member 38 has a lateral insertion groove, which is fixed to the locking pin 32, and the insertion groove is back-to-back with the locking pin 32, and the front end of the leaf spring 37 is inserted into the insertion groove. The rear portion of the leaf spring 37 is fixed to one portion of the plunger 14, which portion faces the outer periphery of the locking pin 32. The leaf spring 37 is used to apply a thrust force in the radial inward direction to the locking pin 32 via the grooved member 38. As a result, when the electromagnetic coil 31 is not energized, the leaf spring 37 presses the locking pin 32 to lock it, and the grooved member 38 is pressed onto the outer periphery of the first part 14c of the plunger 14. When the electromagnetic coil 31 is not energized, the electromagnetic coil 31 attracts the locking pin 32 and moves in the radial direction against the thrust force of the leaf spring 37, and the locking pin 32 further presses the inner end of the electromagnetic coil 31, thereby releasing the lock 30 from the locked state. In this embodiment, the return compression spring 33 is omitted from the previous embodiment.

[0031] Based on the principles of the present application, one skilled in the art can design other configurations of the locking lock 30 .

[0032] Regardless of the specific form of the lock 30, in the original position of the electric brake booster shown in Figures 1 and 2, when the lock 30 is in the locked state, a portion of the lock pin 32 (the radial through hole 14e through which the plunger 14 extends, i.e., the internal cavity portion) is located on the front side of the rebound plate 17, and the axial distance between the portion of the lock pin 32 and the front side of the rebound plate 17 is less than half of the axial movement range of the limiting rod 18 limited by the limiting plate 19, preferably less than one-third, for example less than 3 mm, and preferably less than 2 mm.

[0033] The operation of the lock 30 is related to the brake motor 4. When the brake motor 4 is powered on, the electromagnetic coil 31 of the lock 30 is energized, and when the brake motor 4 is powered off, the power to the electromagnetic coil 31 of the lock 30 is also cut off.

[0034] 3 shows a pedal depression force transmission mechanism (rail) in the electric brake booster. The pedal depression force is transmitted to the pedal spring 16 and the rebound plate 17 via the pressing member 3 and the push rod 15, and the pedal spring 16 and the rebound plate 17 are able to resist the forward movement of the first return spring 21. A radial extension portion 17a is attached or formed at one radial end of the rebound plate 17, and the radial extension portion 17a faces the pedal stroke sensor 6. The axial movement of the radial extension portion 17a can be detected by the pedal stroke sensor 6 (e.g., through a change in a magnetic field), and the control unit 5 can identify the pedal stroke and can also determine the driver's braking intention.

[0035] 4 shows a brake assist force transmission mechanism (rail) in the electric brake booster, in which the driving force (braking assist force) of the brake motor 4 is transmitted to the plunger 14 via the drive nut 12 and the transmission sleeve 11. This resists the forward movement of the plunger 14 caused by the thrust of the second return spring 22, and the plunger 14 outputs the brake assist force generated by the brake motor 4 as an electric brake booster and transmits it to the piston 2.

[0036] It should be noted that in the illustrated example, the braking assist force is transmitted primarily through the drive nut 12 and the transmission sleeve 11. However, it will be appreciated that other mechanisms for converting rotary motion into linear motion, such as a rack and pinion mechanism, can be used to transmit the braking assist force.

[0037] Furthermore, it should be noted that the plunger 14, push rod 15, pedal spring 16 and rebound plate 17 can only move axially and cannot rotate, and that prevention of rotation is achieved by an appropriate limiting structure, for example, through the limiting plate 19 (non-rotatable) and through the limiting rod 18, a restriction is achieved to prevent rotation of the pedal spring 16.

[0038] The operation of the electric brake booster will now be described.

[0039] First, the normal operation mode of the electric brake booster will be described. The so-called normal operation means that the operation of the electric brake booster is started based on the driver stepping on the brake pedal, and the brake motor 4 provides a brake assist force. Before the driver steps on the brake pedal, the brake motor 4 is not powered, and the locking lock 30 is in a locked state. When the driver steps on the brake pedal, the pressing member 3 pushes the pedal spring 16 and the rebound plate 17 forward in the axial direction via the push rod 15. There is a certain distance in the axial direction between the front surface of the rebound plate 17 and the locking pin 32, and within this certain distance in the axial direction, the control unit 5 detects the above-mentioned movement of the pedal spring 16 and the rebound plate 17 by the pedal stroke sensor 6. This confirms that the driver has stepped on the brake pedal, and the brake motor 4 rotates in the forward direction to drive the plunger 14 forward by a specified distance, and at the same time, the electromagnetic coil 31 of the locking lock 30 is energized. As a result, the locking pin 32 contracts in the radial direction, and the locking lock 30 is released from the locking state and does not block the rebound plate 17. Therefore, the locking lock 30 does not impede the operation of the transmission line of the pedal depression force, and the driver can continue to depress the brake pedal, the plunger 14 continues to move forward, the piston 2 moves forward within the cylinder body of the brake master cylinder 1, and an initial pressure is generated within the cylinder body of the brake master cylinder 1. The brake pedal depressed at this stage becomes the idle stroke.

[0040] When the driver further depresses the brake pedal after the end of the idle stroke, the limiting rod 18 and the limiting plate 19 are restricted and cannot continue to move, and both ends of the pedal spring 16 are restricted by the limiting rod 18 and cannot move forward in the axial direction, so that the pedal spring 16 deforms in the axial direction, and the pedal spring 16 gradually increases the repulsive force transmitted to the brake pedal, and at the same time moves the repulsive plate 17 further forward. The control unit 5 determines the driver's intention to brake by detecting the further forward movement by the pedal stroke sensor 6, and controls the forward rotation of the brake motor 4 to drive the plunger 14 further forward by a specified distance. This forward movement of the plunger 14 causes the piston 2 to move further forward within the cylinder body of the brake master cylinder 1, and the brake hydraulic pressure of the brake master cylinder 1 suddenly increases, i.e., it spikes. The brake master cylinder 1 brakes the vehicle by outputting brake fluid with increasing pressure to the braking components of the brake system. Then, the assist force stage is entered, in which the pressure-force curve between the output pressure of the brake master cylinder 1 and the assist force of the booster has a large slope, providing a rapid increase in the non-output pressure.

[0041] When braking is completed, the driver releases the brake pedal, which pushes down the hydraulic pressure in the brake master cylinder 1 and the first return spring 21, causing the rebound plate 17 to move backward, and the control unit 5 determines that the driver's intention to brake has ended and drives the brake motor 4 to rotate in the reverse direction. As a result, the transmission sleeve 11 returns to its original position, and the rebound plate 17, pedal spring 16 and push rod 15 return to their original positions under the action of the first return spring 21, and the plunger 14 also returns to its original position under the action of the second return spring 22. After that, the power supply to the brake motor 4 is cut off, and the locking lock 30 is de-energized, returning to the locked state.

[0042] The present application provides that in a normal operating mode of the electric brake booster, in one aspect, the booster provides a force assist curve similar to that of a conventional vacuum booster, and is therefore capable of replacing the vacuum booster and providing a similar force assist function, while the pedal rebound force and stroke felt by the driver on the brake pedal are similar to those of a conventional brake pedal operation.

[0043] Next, the fully electric operation mode of the electric brake booster will be described below. The so-called single electric operation mode is a state in which the driver does not step on the brake pedal, and the control unit 5 activates the electric brake booster by a braking signal from the automatic braking function of the vehicle, or the automatic braking function of the vehicle directly takes over the control of the electric brake booster. In this case, the push rod 15, the pedal spring 16, and the rebound plate 17 remain stationary, and the control unit 5 controls the forward rotation of the brake motor 4 to drive the plunger 14 forward through the drive nut 12 and the transmission sleeve 11, and presses the piston 2 forward to brake the vehicle. At the same time, the electromagnetic coil 31 of the locking lock 30 is energized, and the locking lock 30 is released from the locking state. When the end of braking is identified, the reverse rotation of the brake motor 4 is controlled to return the transmission sleeve 11 to its original position, and the plunger 14 also returns to its original position under the action of the second return spring 22. Thereafter, the brake motor 4 is powered off and the lock 30 is de-energized, returning to the locked state.

[0044] In both the normal operation mode and the single electric operation mode, the input of the electric brake booster is only from the brake motor 4, and does not have any pedal depression force element. Therefore, both braking modes can be collectively called motor braking operation. In addition, in both the normal operation mode and the single electric operation mode, an auxiliary force ratio and an auxiliary force curve similar to those of a conventional vacuum booster can be provided. Furthermore, the pedal stroke by the driver is used by the control unit 5 to determine the driver's braking intention only in the normal operation mode. In the normal operation mode, the gradually increasing repulsive force due to the deformation of the pedal spring 16 is fed back to the driver's foot via the brake pedal, so that the driver's braking experience is similar to that of a conventional braking system, including a braking system having a conventional vacuum booster.

[0045] Furthermore, the electric brake booster further has a single pedal operation mode. The single pedal operation mode operates when the brake motor 4 does not operate normally or cannot be used, and in this case, no electric energy is supplied to the brake motor 4. At this time, the locking lock 30 is in a locked state, and the locking function of the axial movement of the drive nut 12 is released, so that the drive nut 12 can move in the axial direction. When the driver depresses the brake pedal, the pressing member 3 presses the pedal spring 16 axially forward through the push rod 15, and the axial distance between the rebound plate 17 and the locking pin 32 becomes small, so that the rebound plate 17 presses the locking pin 32 of the locking lock 30 within a short time, and the plunger 14 moves forward, so that the piston 2 is pushed forward, thereby braking the vehicle. When the push rod 15 moves further forward, the pedal spring 16 pulls the limiting plate 19 through the limiting rod 18, and the limiting plate 19 moves axially forward together with the drive nut 12 and the transmission sleeve 11. After braking is completed, the first return spring 21 and the second return spring 22 return the associated parts to their original positions.

[0046] Furthermore, when the electric brake booster is applied to an electric vehicle, it also has the ability to participate in braking energy recovery. In the braking energy recovery operation, the control unit 5 detects depression of the brake pedal and controls the brake motor 4 to drive the plunger 14 to move it forward by a certain set distance. At the same time, the electromagnetic coil 31 of the lock 30 is energized, and the lock 30 is released from the lock state.

[0047] According to the present application, when the motor braking operation is performed, the latch lock is released and the brake booster transmission line is separated from the pedal depression force transmission line. The operation of the brake assist force transmission component does not affect the pedal depression force transmission component and the brake pedal, so the driver does not feel any discomfort from the brake pedal. Furthermore, in the brake motor operation, the input to the electric brake booster is only from the brake motor and is not combined with the pedal depression force.

[0048] When the brake motor is operating normally, the pedal spring is used as a braking behavior simulator to feed back the feeling of the braking state to the driver's foot, and is also used to determine the driver's braking intention, and the pedal depression force is not converted into part of the output of the brake booster. Meanwhile, when a single pedal braking operation is performed, the lock is in a locked state, and the pedal depression force transmission part can move the brake assist force transmission part through the lock, so that the play of the pedal depression force transmission part is reduced and the vehicle is braked quickly.

[0049] Furthermore, the electric brake booster of the present application is particularly suitable for vehicles with an automatic braking function, i.e. the electric brake booster and control of the vehicle braking system are taken over from the automatic braking function, eliminating the need for the driver to press the brake pedal.

[0050] Although the description and application are described herein with reference to specific embodiments, it should be noted that the scope of the application is not limited to the details described. Various changes may be made to these details without departing from the basic principles of the application.

Claims

1. An electric brake booster for use in a vehicle, comprising: A pedal depression force transmission component configured to transmit a pedal depression force from a brake pedal; a brake motor (4) configured to perform a motor braking operation to generate a brake assist force; an assist force transmission component configured to axially press a piston (2) of a brake master cylinder (1); A lock (30) arranged on the auxiliary force transmission component and configured to switch between a locked state and an unlocked state; Equipped with The electric brake booster has a motor braking operation mode and a single pedal braking operation mode, In the motor braking operation mode, the lock is in an unlocked state, whereby the pedal depression force transmission component and the assist force transmission component are kinematically separated, and only the brake assist force generated by the brake motor is transmitted to the piston of the brake master cylinder via the assist force transmission component; In the single pedal braking operation mode, the engagement lock is in an engaged state, whereby the pedal depression force is transmitted to the piston of the brake master cylinder via the pedal depression force transmission component, the engagement lock, and the auxiliary force transmission component; The auxiliary force transmission component includes a drive nut (12) configured to be rotationally driven by the brake motor, and a transmission sleeve (11) connected to the drive nut to convert the rotational motion of the drive nut into linear motion in an axial direction, the auxiliary force transmission component further includes a plunger (14) disposed axially between the piston (2) and the transmission sleeve (11) of the brake master cylinder (1), the plunger being configured to be pressed axially forward by the transmission sleeve (11) toward a cylinder body of the brake master cylinder (1); The pedal force transmission component includes: a push rod (15) arranged in the transmission sleeve (11) and axially slidable therein, a rear portion of the push rod being driven by the brake pedal and a front portion of the push rod extending into an internal cavity (14e) of the plunger (14); a pedal spring (16) supported at a front portion of the push rod (15) and extending radially from the internal cavity (14e), the pedal spring (16) being capable of elastically deforming along an axial direction under the axial pressing action of the push rod (15); a rebound plate (17) supported by a front portion of the push rod (15) in front of the pedal spring (16); An electric brake booster comprising:

2. The motor braking operation includes: a normal braking operation, in which the brake motor (4) is started based on the detected operation of the pedal depression force transmission component, thereby rotating the brake motor (4) in a forward direction to generate a brake assist force; and an independent electric operation, in which the brake motor (4) is started based on a braking signal from an automatic braking module of the vehicle, and the brake motor (4) is rotated in a forward direction to generate a braking assist force; 2. The electric brake booster according to claim 1, comprising:

3. 3. The electric brake booster according to claim 1 or 2, wherein the state of the lock (30) is related to the state of the power supply of the brake motor (4), and when the power supply of the brake motor (4) is turned on, the lock (30) is in an unlocked state, and when the power supply of the brake motor (4) is turned off, the lock (30) is in a locked state.

4. 4. The electric brake booster according to claim 1, wherein in the motor braking operation mode, the pedal spring (16) constructs a braking behavior simulator, the operation of which can be detected to determine the driver's braking intention, and the braking behavior simulator can further feed back a feeling of the braking state to the driver's foot.

5. The locking lock (30) is an electromagnetic coil (31) fixed on the plunger (14); a locking pin (32) made of a magnet and configured to be attracted by the electromagnetic coil when the electromagnetic coil is energized and move to an unlocked position; a return feature configured to return the locking pin to a locked position when the electromagnetic coil is de-energized; The electric brake booster according to claim 1 , further comprising:

6. 6. The electric brake booster according to claim 5, wherein in the locked position, the locking pin is moved to the front side of the rebound plate, and in the unlocked position, the locking pin is completely separated from the front side of the rebound plate.

7. 7. The electric brake booster according to claim 5 or 6, wherein the locking lock (30) further comprises a positioning feature, which is used to limit the position of the locking pin and to hold the locking pin in a locked or unlocked position.

8. The positioning feature comprises: The locking pin is provided on a flange (32c) on its outer periphery. a swinging arm (34) whose one end moves with the locking pin and whose other end is hinged to the plunger; or a leaf spring having one end that moves with the locking pin and the other end that is fixed to the plunger; 8. The electric brake booster according to claim 7, wherein said leaf spring also simultaneously constitutes said return feature.

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