JP2009029364A - Electric booster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve an uncomfortable feeling given to a driver by preventing an excessive pedal stroke from being generated when at emergency braking. <P>SOLUTION: In an electric booster, each front end is made to face a pressure chamber 4 making an input piston 22 moving interlocking with a brake pedal and a booster piston 21 driven by an electric actuator as pistons of a master cylinder 1, and brake liquid pressure is generated on the mater cylinder 1 by input thrust given from the brake pedal into the input piston 22, and booster thrust given from the electric actuator into the booster piston 21. There is provided a fluid chamber 45 in which fluid is filled between the input piston 22 and the booster piston 21. A sliding body 47 having an orifice 50 is installed in the input piston 22. A damping force is generated by the orifice 50 according to relative movement between the input piston 22 and the booster piston 21 so that the input piston 22 is braked to prevent excessive movement. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a booster used in a brake system of an automobile, and more particularly to an electric booster that uses an electric actuator as a booster source.

Conventionally, as this type of electric booster, there is one described in Patent Document 1. The input member includes an input member that moves in conjunction with a brake pedal, an assist member that is arranged to be relatively movable with the input member, and an electric actuator that moves the assist member forward and backward. The input member and the assist member With the front end of the master cylinder facing the pressure chamber of the master cylinder, an input thrust applied to the input member from the brake pedal, and a booster thrust applied to the assist member from the electric actuator, Thus, the brake fluid pressure is generated in the pressure chamber of the master cylinder.
Japanese Patent Laid-Open No. 2007-112426

  However, in the electric booster described in Patent Document 1, the displacement of the input member is detected by the displacement detection means, and the electric actuator is operated based on the detection signal. There is a tendency for a slight time delay to occur. For this reason, when the brake pedal is stepped on suddenly to apply a sudden brake, a time delay occurs in the increase of the brake fluid pressure generated in the master cylinder, and the movement stroke of the input member, that is, the pedal stroke becomes larger than necessary. In addition, as the brake fluid pressure increases, the hydraulic reaction force applied to the input member increases, causing the brake pedal to be pushed back, causing the driver to feel uncomfortable.

  The present invention has been made in view of the above-described conventional problems, and the object of the present invention is to prevent an unnecessarily pedal stroke from occurring even during sudden braking, and thus greatly improve the uncomfortable feeling given to the driver. It is in providing the electric booster which contributes.

  In order to solve the above problems, the present invention includes an input member that moves in conjunction with a brake pedal, an assist member that is arranged to be relatively movable with the input member, and an electric actuator that moves the assist member forward and backward. The input member and the assist member are pistons of the master cylinder, the front ends of the input member and the assist member face the pressure chamber of the master cylinder, the input thrust applied to the input member from the brake pedal, and the assist member from the electric actuator. In the electric booster that generates the brake fluid pressure in the pressure chamber of the master cylinder by the booster thrust applied to the cylinder, a braking force is applied to the input member in accordance with the relative movement of the input member and the assist member. A braking force applying means is provided.

  In the present invention, the input member extends through the inside of a cylindrical assist member, and the braking force applying means is disposed between the input member and the assist member. can do.

  In the present invention, the braking force applying means may be configured by a damping force generating mechanism that generates a damping force in accordance with the relative movement between the input member and the assist member.

  In this case, the damping force generating mechanism includes a fluid chamber defined between the input member and the assist member and enclosing a fluid, and a sliding body that is attached to the input member and bisects the fluid chamber in the axial direction. And an orifice provided in the sliding body.

  The damping force generation mechanism also includes a fluid chamber defined between the input member and the assist member and communicating with the pressure chamber of the master cylinder, and a slide fixed to the input member and dividing the fluid chamber in the axial direction. It is good also as a structure which consists of a moving body and the orifice provided in this sliding body.

  The damping force generating mechanism further includes a bottomed tubular member integrally disposed with the assist member in the pressure chamber of the master cylinder, a tubular member defined in the tubular member, and a front end portion of the input member It is good also as a structure which consists of the inserted fluid chamber and the orifice provided in this cylindrical member.

  In the present invention, the braking force applying means may be configured by a friction force generating mechanism that generates a friction force between the input member and the assist member in accordance with relative movement between the input member and the assist member.

  In this case, the frictional force generating mechanism is formed of a cylindrical spring body capable of expanding and contracting diameter, and the spring body is interposed between the input member and the assist member in a contracted state, and the spring body itself is elastic. It is good also as a structure which generates a frictional force between these both members with force.

  The frictional force generating mechanism is also composed of a cylindrical spring body capable of expanding and contracting, and the spring body expands in accordance with the deflection of a balance spring interposed between the input member and the assist member, A configuration may be adopted in which a frictional force is generated between the two members.

  The frictional force generating mechanism further comprises a spiral spring body capable of expanding and contracting, and the spring body is interposed between the input member and the assist member, and is compressed in the axial direction in accordance with the relative movement of the both members. Then, the diameter may be increased to generate a frictional force between the two members.

  According to the electric booster of the present invention, the reaction force against the input member substantially increases from the initial operation, so that even if there is a time delay in the generation of the brake fluid pressure in the master cylinder, the pedal stroke is reduced. It does not become larger than necessary, and the driver's discomfort is greatly improved.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  1 and 2 show a first embodiment of an electric booster according to the present invention. The electric booster 10 as the first embodiment is an apparatus in which a rear end portion is fixed to a vehicle compartment wall W that partitions an engine room and a vehicle compartment, and a tandem master cylinder 1 described later is consolidated to the front end portion. A main body 11, a piston assembly 20, which will be described later, disposed in the apparatus main body 11 and used as a primary piston of the master cylinder 1, and disposed inside and outside the apparatus main body 11, constitute the piston assembly 20. And an electric actuator 30 (described later) for applying a thrust (booster thrust) to the booster piston (assist member) 21 that performs the booster piston. The apparatus body 11 includes a large-diameter cup member 12 fixed to the casing wall W, a cylindrical member 13 to which the master cylinder 1 is consolidated, and a cylinder connecting the cup member 12 and the cylindrical member 13. The connecting member 14 is integrated with the cup member 12 via a support plate 15 fixed to the open end of the cup member 12. A hollow boss portion 12a is provided at the bottom of the cup member 12, and the tip end portion of the boss portion 12a extends through the vehicle interior wall W into the vehicle interior.

  The tandem master cylinder 1 includes a cylinder body 2 with a bottom and a reservoir (not shown), and a secondary piston that forms a pair with the piston assembly 20 as the primary piston on the inner side of the cylinder body 2. 3 is slidably arranged. In the cylinder body 2, two pressure chambers 4, 5 are defined by the piston assembly 20 and the secondary piston 3, and the pressure chambers 4, 5 correspond to the advance of the pistons 20, 3. The brake fluid sealed inside is pressure-fed from a discharge port (not shown) to a corresponding wheel cylinder. In each of the pressure chambers 5 and 6, return springs 6 and 7 for urging the piston assembly 20 as the primary piston and the secondary piston 3 rearward are disposed. The cylinder body 2 is provided with a relief port that communicates the inside of the pressure chambers 4 and 5 with the reservoir 11, but this is not shown.

  The piston assembly 20 constituting the electric booster 10 is composed of the booster piston 21 and an input piston (input member) 22 disposed in the booster piston 21 so as to be movable relative thereto. An input rod 23 interlocked with a brake pedal (not shown) is connected to the rear end portion of the input piston 22 via a joint 24. The input piston 22 is disposed in the booster piston 21 by operating the brake pedal (pedal operation). Move forward and backward.

  The booster piston 21 constituting the piston assembly 20 has a partition wall 25 at an intermediate portion in the longitudinal direction therein, and the input piston 22 extends through the partition wall 25. The front end side of the booster piston 21 is inserted into the pressure chamber (primary chamber) 4 in the master cylinder 1, while the front end side of the input piston 22 is positioned inside the booster piston 21 in the same pressure chamber 13. Yes. The booster piston 21 and the input piston 22 are sealed by a seal member 26 fitted to the partition wall 25, and the booster piston 21 and the apparatus main body 11 are sealed by a seal member 27, respectively. The brake fluid is prevented from leaking out from the master cylinder 1.

  The electric actuator 30 is located outside the cylindrical member 13 constituting the apparatus main body 11 and fixed to the support plate 15. The electric actuator 30 is also connected to the input piston 22 inside the connecting member 14 constituting the apparatus main body 11. And a rotation transmitting mechanism 33 that decelerates the rotation of the electric motor 31 and transmits the rotation to the ball screw mechanism 32. The ball screw mechanism 32 includes a nut member (rotating member) 35 rotatably supported by the connecting member 14 via a bearing (angular contact bearing) 34 and a hollow member engaged with the nut member 35 via a ball 36. It consists of a screw shaft (linear motion member) 37. The rear end portion of the screw shaft 37 is non-rotatably and slidably fitted to the hollow boss portion 12 a of the cup member 12 constituting the apparatus main body 11, whereby the screw shaft 37 is screwed according to the rotation of the nut member 35. The shaft 37 moves linearly.

  On the other hand, the rotation transmission mechanism 33 constituting the electric actuator 30 includes a first pulley 38 attached to the output shaft 31a of the electric motor 31 and a second pulley 39 fitted non-rotatably to the nut member 35. And a belt (timing belt) 40 wound around the two pulleys 38 and 39. The second pulley 39 has a larger diameter than the first pulley 38, whereby the rotation of the electric motor 31 is decelerated and transmitted to the nut member 35 of the ball screw mechanism 32. The rotation transmission mechanism 33 is not limited to the pulleys and belts described above, and may be a reduction gear mechanism, a linear motion mechanism, or the like.

  A flange member 41 that also functions as a guide for slidingly guiding the input piston 22 is fitted and fixed to a front end portion of a hollow screw shaft 37 constituting the ball screw mechanism 32. The flange member 41 comes into contact with a lid 42 fitted to the rear end of the booster piston 21 as the screw shaft 37 advances in the left direction in the drawing. The booster piston 21 is also advanced in accordance with the advance. In addition, one end of the cylindrical member 13 constituting the apparatus body 11 is locked to an annular protrusion 13 a formed on the cylindrical member 13 via a spring receiver 43, and the other end is opposed to the flange member 41. A return spring 44 is provided, and the screw shaft 37 is positioned at the original position shown in the drawing by the return spring 44 when the brake is not operated.

  Here, an annular chamber 45 is defined between the booster piston 21 and the input piston 22, and this annular chamber 45 is mounted on the input piston 22, and a seal member 46 is provided on the inner surface of the booster piston 21. The sliding body 47 is bisected in the axial direction by the sliding body 47. A pair of balance springs 48 for holding the input piston 22 and the booster piston 21 in a neutral position relative to each other when the brake is not operated are disposed in the two front and rear chambers of the annular chamber 45 divided into two by the sliding body 47. ing.

  In the first embodiment, the annular chamber 45 includes the sealing member 27 interposed between the partition wall 26 of the booster piston 21 and the input piston 22, and a lid body fitted to the rear end portion of the booster piston 21. 42 and the input piston 22 are configured as a sealed chamber. The annular chamber 45 has a compressible fluid (oil, air) or an incompressible fluid (brake fluid). Is enclosed. Thus, a plurality of axial grooves 50 are provided in the circumferential direction on the inner surface of the sliding body 47 (the fitting surface for the fluid piston 22). The groove 50 functions as an orifice that communicates the two chambers divided into two by the sliding body 47. With this, when the input piston 22 and the booster piston 21 move relative to each other, the two chambers pass through the orifice (groove) 50. A fluid flows and a damping force is generated by the flow resistance at this time.

  A displacement detector (potentiometer) 51 for detecting the absolute displacement of the input piston 22 relative to the vehicle body is disposed between the cup member 12 constituting the apparatus main body 11 and the input rod 23, and the electric motor 31. Includes a rotation detector (resolver) 52 for detecting a rotation angle. The signals of the displacement detector 51 and the rotation detector 52 are sent to a controller (control device) 53. The controller 53 is based on the signals from the displacement detector 51 and the rotation detector 52. The rotation of the electric motor 31 is controlled.

  Hereinafter, the operation of the electric booster 10 configured as described above will be described.

  When the brake pedal is operated, the input piston 22 moves forward, and the movement is detected by the displacement detector 51. Then, in response to the signal from the displacement detector 51, the controller 53 outputs a start command to the electric motor 31, whereby the electric motor 31 rotates and the rotation is transmitted to the ball screw mechanism 32 via the rotation transmission mechanism 33. As a result, the screw shaft 37 advances. Then, the booster piston 21 is pushed forward by the screw shaft 37 and the brake hydraulic pressure corresponding to the input thrust applied from the brake pedal to the input piston 22 and the booster thrust applied from the electric actuator 30 to the booster piston 21 is increased. It occurs in the pressure chambers 4 and 5 in the master cylinder 1.

  At this time, based on the detection signals of the displacement detector 51 and the rotation detector 52, the relative displacement amount of both pistons can be determined from the difference between the absolute displacement of the input piston 22 and the absolute displacement of the booster piston 21. Therefore, when the rotation of the electric motor 31 is controlled so that relative displacement does not occur between the input piston 22 and the booster piston 21, the pair of balance springs 48 interposed between the pistons 22 and 21 set the neutral position. maintain. The boost ratio at this time is uniquely determined by the area ratio between the pressure receiving area of the booster piston 21 and the pressure receiving area of the input piston 22 because the relative displacement amount is 0, and is the same as that of a general-purpose vacuum booster. Become.

  On the other hand, when the booster piston 21 is relatively displaced from the neutral position in the direction (forward) in which the brake fluid pressure is increased by the booster thrust, the boost ratio (braking force) increases, and the electric motor 31 works as a boost source. Brake assist operation is realized. Conversely, when the booster piston 21 is relatively displaced from the neutral position in the direction (rearward) in which the brake hydraulic pressure is reduced by the booster thrust, the boost ratio (braking force) is reduced, and regenerative cooperative operation during regenerative braking is realized. . Further, since the communication between the pressure chambers 4 and 5 in the master cylinder 1 and the reservoir is blocked by the advance of the booster piston 21, automatic braking operations such as adaptive control (ACC) and hill start assist are also possible.

  By the way, in this electric booster 10, since the displacement detector 51 detects the displacement of the input piston 22 as described above and operates the electric actuator 30 based on the detection signal, a booster piston (assist member). There is a slight time delay in the movement (advance) of 21. For this reason, when the brake pedal is stepped on suddenly to apply the brake suddenly, a time delay occurs in the increase of the brake fluid pressure generated in the master cylinder 1, and the moving stroke of the input piston 22, that is, the pedal stroke is more than necessary. Become bigger. However, in the first embodiment, when the input piston 22 moves rapidly, the fluid in the annular chamber (fluid chamber) 45 between the input piston 22 and the booster piston 21 is slid on the input piston 22. It flows through the orifice (groove) 50 in the moving body 47 and a damping force is generated. This damping force acts as a braking force that suppresses the movement of the input piston 22, thereby substantially increasing the reaction force against the input piston 22 from the beginning of operation. As a result, even if the brake pedal is suddenly depressed, the input piston 22 The driver will not move more than necessary, and the driver will not feel uncomfortable.

  FIG. 3 shows a second embodiment of the electric booster according to the present invention. The overall configuration of the electric booster in each embodiment described below is the same as that of the first embodiment. Therefore, in the following, the entire structure is omitted and only the main part structure is shown. The same parts as those shown in FIG. The feature of the second embodiment is that the seal member 27 (FIG. 2) is omitted from between the partition wall 26 of the booster piston 21 and the input piston 22, and between the booster piston 21 and the input piston 22. The annular chamber (fluid chamber) 45 is communicated with the pressure chamber (primary chamber) 4 in the master cylinder 1.

  The basic operation and effect of the second embodiment is the same as that of the first embodiment. When the input piston 22 moves rapidly due to sudden depression of the brake pedal, the brake in the annular chamber (fluid chamber) 45 is The liquid flows through the orifice (groove) 50 in the sliding body 47 attached to the input piston 22 to generate a damping force. The damping force is applied to the input piston 22 to suppress its movement. In this case, since the incompressible brake fluid flows through the orifice 50, a larger damping force can be obtained, and the movement of the input piston 22 more than necessary can be more reliably suppressed.

  FIG. 4 shows a third embodiment of the electric booster according to the present invention. In the third embodiment, the seal member 49 (FIG. 2) is omitted from between the input piston 22 and the lid body 42 fitted to the rear end portion of the booster piston 21, and the booster piston 21 and the input piston 22 are omitted. An annular chamber (fluid chamber) 45 between the two is opened to the atmosphere. Further, the sliding body 47 (FIG. 2) having the orifice 50 is omitted from the input piston 22, and instead, a simple flange 22a is provided on the input piston 22, and the pair of balance springs 48 are supported by the flange 22a. I have to. Further, a bottomed cylindrical member 56 having an orifice 55 is disposed in the pressure chamber (primary chamber) 4 in the master cylinder 1, and the inside of the cylindrical member 56 is configured as a fluid chamber 57, The front end portion of the input piston 22 is inserted into the fluid chamber 57. The tubular member 56 is pressed and fixed to the partition wall 25 of the booster piston 21 by a return spring 6 disposed in the pressure chamber 4 of the master cylinder 1.

  The basic operation and effects of the third embodiment are the same as those of the first embodiment, but when the input piston 22 moves rapidly due to sudden depression of the brake pedal, the inside of the cylindrical member 56 is The brake fluid in the fluid chamber 57 flows out through the orifice 55 to generate a damping force, and the input piston 22 is braked by this damping force. In this case, the incompressible brake fluid flows through the orifice 55, so that a larger damping force can be obtained as in the second embodiment. In addition, the fluid chamber 57 is provided in the pressure chamber 4 of the master cylinder 1. Since it is defined, it is difficult for air to accumulate, and a large damping force can be obtained stably.

  FIG. 5 shows a fourth embodiment of the electric booster according to the present invention. In the fourth embodiment, the seal member 49 (FIG. 2) is omitted between the lid 42 and the input piston 22 fitted to the rear end portion of the booster piston 21, and the booster piston 21 and the input piston 22 are omitted. An annular chamber (fluid chamber) 45 between the two is opened to the atmosphere. Further, the sliding body 47 (FIG. 2) having the orifice 50 from the input piston 22 is omitted, and instead, a pair of flanges 22a are provided at a predetermined interval on the input piston 22, and a groove between the pair of flanges 22a. A cylindrical spring body 60 having the shape shown in FIG. 6 is disposed therein. The pair of balance springs 48 are supported by the flange 22a.

  As shown in FIG. 6, the cylindrical spring body 60 can be expanded and contracted in diameter by dividing one circumferential portion by a slit 60 a. Here, the spring body 60 is interposed between the input piston 22 and the booster piston 21 in a reduced diameter state, and the outer peripheral surface of the spring body 60 is the inner peripheral surface of the booster piston 21 by its own elastic force (elastic restoring force). In frictional contact. The spring body 60 is fixed in the axial direction with respect to the input piston 22 by a pair of flanges 22a. With this, when the input piston 22 and the booster piston 21 move relative to each other, the outer peripheral surface of the spring body 60 is fixed. And the booster piston 21 are caused to generate a frictional force.

  The basic operational effects of the fourth embodiment are the same as those of the first embodiment. However, when the input piston 22 moves rapidly due to sudden depression of the brake pedal, the outer peripheral surface of the spring body 60. And the booster piston 21 generate frictional force to brake the input piston 22. As a result, the reaction force against the input piston 22 substantially increases from the beginning of operation, and the input piston 22 does not move more than necessary even when the brake pedal is suddenly depressed. As a result, the driver does not feel uncomfortable. . Particularly in the fourth embodiment, since only a single cylindrical spring body 60 is interposed between the input piston 22 and the booster piston 21, a damping force generation mechanism is provided as in the first to third embodiments. The structure of the braking force applying means is simpler than the case of providing the above.

  In addition, as shown in FIG. 7, the cylindrical spring body 60 may be held by a cover body 42 that is integral with the booster piston 21. In this case, the same function and effect as in the fourth embodiment are also possible. Is obtained.

  FIG. 8 shows a fifth embodiment of the electric booster according to the present invention. In the fifth embodiment, the seal member 49 (FIG. 2) is omitted from between the lid body 42 fitted to the rear end portion of the booster piston 21 and the input piston 22 as in the fourth embodiment. The annular chamber (fluid chamber) 45 between the booster piston 21 and the input piston 22 is opened to the atmosphere. Further, the sliding body 47 (FIG. 2) having the orifice 50 is omitted from the input piston 22, and a flange 22a is provided in the input piston 22 instead, and a pair of balance springs 48 are supported on the flange 22a. A feature of the fifth embodiment is that, instead of the cylindrical elastic body 60 (FIG. 6) used in the fourth embodiment, a cylindrical shape thinner than the elastic body 60 as shown in FIG. The elastic body 61 is used, and the elastic body 61 is placed in the annular chamber 45 in a form in which the elastic body 61 is externally fitted to the balance spring 48 on the front side (master cylinder side). The shape of the elastic body 61 is substantially the same as that of the elastic body 60 in the fourth embodiment, and one portion in the circumferential direction is divided by the slit 61a so that the diameter can be increased or decreased.

  The cylindrical spring body 61 is interposed between the input piston 22 and the booster piston 21 in a natural state. Of the pair of balance springs 48, the front balance spring is compressed and expanded in diameter when the input piston 22 moves forward with respect to the booster piston 21 by a pedal operation. Accordingly, the cylindrical spring body 61 is expanded and the outer peripheral surface thereof is brought into frictional contact with the inner peripheral surface of the booster piston 21. Thus, when the input piston 22 moves forward with respect to the booster piston 21, a frictional force is generated between the outer peripheral surface of the spring body 60 and the inner peripheral surface of the booster piston 21.

  The basic operational effects of the fifth embodiment are the same as those of the first embodiment. However, when the input piston 22 moves rapidly due to a sudden depression of the brake pedal, the outer peripheral surface of the spring body 61. And the booster piston 21 generate frictional force to brake the input piston 22. As a result, the reaction force against the input piston 22 substantially increases from the beginning of operation, and the input piston 22 does not move more than necessary even when the brake pedal is suddenly depressed. As a result, the driver does not feel uncomfortable. . Particularly in the fifth embodiment, since the spring body 61 is interposed between the input piston 22 and the booster piston 21 in a natural state, the assemblability is improved as compared with the fourth embodiment. .

  FIG. 10 shows a sixth embodiment of the electric booster according to the present invention. A feature of the sixth embodiment is that a spiral spring body 62 having the shape shown in FIG. 11 is provided in the annular chamber 45 between the input piston 22 and the booster piston 21 instead of the pair of balance springs 48. It is in the point paid. The spiral spring body 62 is expanded in diameter by being compressed in the axial direction. When the input piston 22 and the booster piston 21 move relative to each other, the spring body 62 expands in diameter. The outer peripheral surface is brought into frictional contact with the inner peripheral surface of the booster piston 21. The spiral spring body 62 is interposed between the input piston 22 and the booster piston 21 in a natural state.

  The basic operational effects of the sixth embodiment are the same as those of the first embodiment, but when the input piston 22 moves rapidly due to sudden depression of the brake pedal, the outer peripheral surface of the spring body 62 And the booster piston 21 generate frictional force to brake the input piston 22. As a result, the reaction force against the input piston 22 substantially increases from the beginning of operation, and the input piston 22 does not move more than necessary even when the brake pedal is suddenly depressed. As a result, the driver does not feel uncomfortable. . Particularly in the sixth embodiment, since the spring body 62 is interposed between the input piston 22 and the booster piston 21 in a natural state, the assemblability is improved as in the fifth embodiment. . Further, since the spring body 62 is also used as a balance spring, the number of parts is reduced by the amount that the balance spring can be omitted, which is advantageous in terms of cost.

  The effects of the present invention according to the above embodiment are as follows.

  An input member that moves in conjunction with a brake pedal, an assist member that is arranged to be movable relative to the input member, and an electric actuator that moves the assist member forward and backward, and the input member and the assist member are connected to a master cylinder. As the pistons of the master cylinder, the front end portions of the pistons face the pressure chambers of the master cylinder, and the master cylinder is configured by the input thrust applied from the brake pedal to the input member and the booster thrust applied from the electric actuator to the assist member. In the electric booster for generating the brake fluid pressure in the pressure chamber, provided is a braking force applying means for applying a braking force to the input member in accordance with the relative movement of the input member and the assist member. To do.

  In the electric booster configured as described above, the braking force is applied from the braking force applying means to the input member in accordance with the relative movement between the input member and the assist member. As a result, even if a time delay occurs in the generation of the brake fluid pressure in the master cylinder, the pedal stroke does not become larger than necessary.

  In the present invention, the input member extends through the inside of a cylindrical assist member, and the braking force applying means is disposed between the input member and the assist member. can do. Thus, when the input member is extended through the inside of the assist member, the braking force applying means can be easily installed using the space between the two members.

  In the present invention, the braking force applying means may be configured by a damping force generating mechanism that generates a damping force in accordance with the relative movement between the input member and the assist member. In such a configuration, the damping force generated in accordance with the relative movement between the input member and the assist member acts as a braking force that suppresses the movement of the input member, so that the reaction force against the input member is substantially reduced from the initial operation. To increase.

  In this case, the damping force generation mechanism includes a fluid chamber defined between the input member and the assist member and sealed with a compressible fluid, and attached to the input member, and the fluid chamber is divided into two in the axial direction. It is good also as a structure which consists of the sliding body to perform and the orifice provided in this sliding body. In this case, since the fluid in the fluid chamber passes through the orifice in accordance with the relative movement between the input member and the assist member, a damping force is generated by the passage resistance.

  The damping force generation mechanism also includes a fluid chamber defined between the input member and the assist member and communicating with the pressure chamber of the master cylinder, and a slide fixed to the input member and dividing the fluid chamber in the axial direction. It is good also as a structure which consists of a moving body and the orifice provided in this sliding body. In this case, since the incompressible brake fluid in the master cylinder can be introduced into the fluid chamber, a larger damping force can be obtained.

  The damping force generating mechanism further includes a bottomed tubular member integrally disposed with the assist member in the pressure chamber of the master cylinder, a tubular member defined in the tubular member, and a front end portion of the input member It is good also as a structure which consists of the inserted fluid chamber and the orifice provided in this cylindrical member. In this case, since the fluid chamber is defined in the pressure chamber of the master cylinder, it is difficult for air to accumulate, and in combination with the use of the incompressible brake fluid, a large damping force can be stably obtained.

  In the present invention, the braking force applying means may be configured by a friction force generating mechanism that generates a friction force between the input member and the assist member in accordance with relative movement between the input member and the assist member. In such a configuration, the frictional force generated according to the relative movement between the input member and the assist member acts as a braking force that suppresses the movement of the input member, and thus the reaction force against the input member is substantially reduced from the initial operation. To increase.

  In this case, the frictional force generating mechanism is formed of a cylindrical spring body capable of expanding and contracting, and the spring body is interposed between the input member and the assist member in a contracted state, and the elastic force is applied to the spring body. It is good also as a structure which generates a frictional force between both members. In this case, since only a single cylindrical spring body is interposed between the input member and the assist member, the structure of the braking force applying means is simplified.

  The frictional force generating mechanism is also composed of a cylindrical spring body capable of expanding and contracting, and the spring body expands in accordance with the deflection of a balance spring interposed between the input member and the assist member, A configuration may be adopted in which a frictional force is generated between the two members. In this case, since the diameter of the cylindrical spring body is increased in accordance with the bending of the balance spring, it is not necessary to insert the cylindrical spring body in a compressed state between the input member and the assist member, and the assembling property is improved. Improved.

  The frictional force generating mechanism further comprises a spiral spring body capable of expanding and contracting, and the spring body is interposed between the input member and the assist member, and is compressed in the axial direction in accordance with the relative movement of the both members. Then, the diameter may be increased to generate a frictional force between the two members. In this case, since it is not necessary to interpose in a compressed state, in addition to improving the assemblability, it can be shared as a balance spring.

It is sectional drawing which shows the whole structure of the electric booster as the 1st Embodiment of this invention. It is sectional drawing which shows the principal part structure of the electric booster as 1st Embodiment. It is sectional drawing which shows the principal part structure of the electric booster as the 2nd Embodiment of this invention. It is sectional drawing which shows the principal part structure of the electric booster as the 3rd Embodiment of this invention. It is sectional drawing which shows the principal part structure of the electric booster as the 4th Embodiment of this invention. It is a perspective view which shows the external appearance shape of the spring body used by 4th Embodiment. It is sectional drawing which shows the principal part structure of the electric booster as a modification of 4th Embodiment. It is sectional drawing which shows the principal part structure of the electric booster as the 5th Embodiment of this invention. It is a perspective view which shows the external appearance shape of the spring body used in 5th Embodiment. It is sectional drawing which shows the principal part structure of the electric booster as the 6th Embodiment of this invention. It is a perspective view which shows the external appearance shape of the spring body used by 6th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Master cylinder 4,5 Pressure chamber of master cylinder 10 Electric booster 11 Apparatus main body 20 Piston assembly 21 Booster piston (assist member)
22 Input piston (input member)
30 Electric Actuator 31 Electric Motor 32 Ball Screw Mechanism (Rotation-Linear Conversion Mechanism)
33 Motion transmission mechanism 45 Annular chamber (fluid chamber)
48 Balance spring 47 Slider 50 Groove (orifice)
56 Cylindrical member with bottom 55 Orifice 60, 61, 62 Spring body

Claims (10)

  An input member that moves in conjunction with a brake pedal, an assist member that is arranged to be movable relative to the input member, and an electric actuator that moves the assist member forward and backward, and the input member and the assist member are connected to a master cylinder. As the pistons of the master cylinder, the front end portions of the pistons face the pressure chambers of the master cylinder, and the master cylinder is configured by the input thrust applied from the brake pedal to the input member and the booster thrust applied from the electric actuator to the assist member. In the electric booster for generating the brake fluid pressure in the pressure chamber, provided is a braking force applying means for applying a braking force to the input member in accordance with the relative movement of the input member and the assist member. Electric booster to do.   The input member is extended through an inside of a cylindrical assist member, and a braking force applying means is disposed between the input member and the assist member. The electric booster according to 1.   3. The electric booster according to claim 2, wherein the braking force applying means includes a damping force generating mechanism that generates a damping force in accordance with relative movement between the input member and the assist member.   A damping force generating mechanism defined between an input member and an assist member and enclosing a fluid; a sliding body mounted on the input member and bisecting the fluid chamber in the axial direction; and the sliding member The electric booster according to claim 3, comprising an orifice provided in the moving body.   A damping force generating mechanism defined between the input member and the assist member and communicating with the pressure chamber of the master cylinder; a sliding body fixed to the input member and bisecting the fluid chamber in the axial direction; The electric booster according to claim 3, further comprising an orifice provided in the sliding body.   A damping force generating mechanism is formed with a bottomed cylindrical member integrally disposed with the assist member in the pressure chamber of the master cylinder, and is defined in the cylindrical member, and a front end portion of the input member is inserted. The electric booster according to claim 3, comprising: a fluid chamber and an orifice provided in the cylindrical member.   3. The electric motor according to claim 2, wherein the braking force applying means comprises a frictional force generating mechanism that generates a frictional force between the input member and the assist member in accordance with relative movement between the input member and the assist member. Boost device.   The frictional force generating mechanism is formed of a cylindrical spring body capable of expanding and contracting diameter, and the spring body is interposed between the input member and the assist member in a contracted state, and both the spring bodies themselves are caused by the elastic force of the spring body itself. 8. The electric booster according to claim 7, wherein a frictional force is generated between the members.   The frictional force generating mechanism is formed of a cylindrical spring body capable of expanding and contracting, and the spring body expands in accordance with the deflection of a balance spring interposed between the input member and the assist member. 8. The electric booster according to claim 7, wherein a frictional force is generated between the members.   The frictional force generating mechanism is composed of a spiral spring body capable of expanding and contracting, and the spring body is interposed between the input member and the assist member, and is compressed in the axial direction in accordance with relative movement of the two members. The electric booster according to claim 7, wherein the electric booster expands the diameter and generates a frictional force between the two members.

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