JP6326978B2 - Negative pressure booster - Google Patents

Description

  The present invention relates to a negative pressure booster employed in a vehicle brake device. More specifically, the invention makes it possible to reduce the thickness of the pressure plate provided inside the booster shell.

  The negative pressure type booster mentioned above includes a partition member constituting a power piston inside the booster shell. The partition member is a combination of a pressure plate and a diaphragm, and the partition member divides the interior of the booster shell into a constant pressure chamber and a variable pressure chamber.

  The power piston is configured by attaching a valve piston having a negative pressure valve and an atmospheric valve inside to a central portion of the partition member.

  The constant pressure chamber is connected to an air supply manifold of the engine, and air is introduced into the variable pressure chamber from the outside via the atmospheric valve when the booster is activated.

  In this negative pressure type booster, when a brake operation is performed, the negative pressure valve is closed, the communication between the constant pressure chamber and the variable pressure chamber is cut off, and then the atmospheric valve is opened and the atmosphere is introduced into the variable pressure chamber from the outside. As a result, a pressure difference is generated between the constant pressure chamber and the variable pressure chamber, the power piston moves forward in response to the pressure difference, and the master cylinder is operated with a force amplified according to the brake operation force. This operating mechanism is well known and will not be described in detail.

  Among such negative pressure boosters, there is one that uses two tie rods to fasten a master cylinder to a booster shell. Here, it is called a tie rod negative pressure booster. The tie rod is also used to fix the booster shell to the car body.

  As a prior art of the tie rod type negative pressure booster, for example, there is one disclosed in Patent Document 1 below.

  The two tie rods are respectively inserted into the tie rod holes by providing tie rod holes in the front shell, the rear shell and the partition member constituting the booster shell.

  The tie rod hole provided in the pressure plate of the partition member is at a position biased toward the center hole side of the pressure plate to which the valve piston is attached.

  The pressure plate is required to have durability and pressure strength. Conventionally, in order to meet the demand, a method has been adopted in which the plate is drawn to have reinforcing ribs and the plate thickness is increased to some extent.

JP 2006-224958 A

  In order to reduce vehicle weight and cost, it has been studied to reduce the thickness of the pressure plate. In order to meet the demand with the conventional plate shape, it is necessary to deepen the drawing amount in press molding.

  However, if the plate is deepened, the moldability deteriorates. For this reason, the number of molding steps must be increased. This hindered the limitation of further thinning the pressure plate.

  This invention makes it possible to reduce the thickness of the pressure plate of the power piston of the tie rod type negative pressure booster without increasing the amount of squeezing, and the pressure strength and durability required for the pressure plate thinner than before. It is an issue to be able to ensure.

In order to solve the above problem, the present invention is configured such that the partition member of the power piston that partitions the interior of the booster shell into a constant pressure chamber and a variable pressure chamber is composed of a pressure plate and a diaphragm.
The pressure plate has an umbrella-shaped portion inclined with respect to a line orthogonal to the central axis between an inner diameter side and an outer diameter side that are drawn and connected to the valve piston,
Tie rods that fasten the master cylinder to the booster shell are inserted airtightly into two tie rod holes respectively provided in the umbrella-shaped portion of the booster shell and the pressure plate,
The tie rod hole is configured as follows as a negative pressure booster in which a straight line connecting the hole centers of two holes passes through the center of the pressure plate.

  That is, the slope angle of the umbrella-shaped portion of the pressure plate is differentiated between a tie rod hole installation region in which the tie rod hole is formed and another region displaced in the circumferential direction from the tie rod hole installation region. The slope angle of was made larger than that of other areas.

  In addition, the said tie rod hole installation area | region means the area | region which has the circumferential direction width | variety which can accommodate a tie rod hole, and extends in the radial direction of an umbrella-shaped part.

  Such a negative pressure booster is preferably one in which the slope angle of each circumferential portion of the umbrella-shaped portion of the pressure plate is smoothly changed from the other region toward the tie rod hole installation region.

  The slope angle change point on the tie rod hole installation region side is preferably arranged in the vicinity of both ends of the pressure plate in the circumferential direction of the tie rod hole.

  The slope angle change point on the other region side may be on a line orthogonal to the straight line connecting the centers of the two tie rod holes provided in the pressure plate at the center of the pressure plate, and from there It may be in a position biased toward the tie rod hole installation region side (preferably on a line that intersects an acute angle at the center of the pressure plate with respect to the straight line connecting the centers of the two tie rod holes).

  The umbrella-shaped portion of the pressure plate is composed of an inner-diameter-side umbrella-shaped portion and an outer-diameter-side umbrella-shaped portion surrounding the outer periphery of the inner-diameter-side umbrella-shaped portion, and the radially outer end of the inner-diameter-side umbrella-shaped portion and the outer A bending return portion is provided between the radially inner ends of the radial umbrella-shaped portions so that the radially inner end position of the outer-diameter umbrella-shaped portion is more narrow than the radially outer end position of the radially inner umbrella-shaped portion. It is also preferable to retract in the direction of shallowing (here, this is referred to as a two-stage aperture-shaped umbrella-like portion).

  The pressure plate having the umbrella-shaped portion in the shape of the two-stage throttle is provided with the tie rod hole in the inner diameter side umbrella-shaped portion, and only the inner diameter side umbrella-shaped portion has different slope angles of the tie rod hole installation region and other regions. Good.

  The negative pressure booster according to the present invention can ensure the required pressure strength and durability by reducing the thickness of the pressure plate without increasing the depth of the diaphragm by the above-described configuration.

  When the driver performs a braking operation on the vehicle and the negative pressure booster is activated, a load is applied to the pressure plate so as to bend the plate due to a pressure difference generated between the constant pressure chamber and the variable pressure chamber.

  The strength of the pressure plate with respect to the load is the weakest in the installation area of the tie rod hole where stress tends to concentrate (particularly, the area sandwiched between the tie rod hole and the center hole of the pressure plate).

  In the negative pressure type booster of the present invention, the slope angle of the tie rod hole installation region of the umbrella-shaped portion is made larger than the slope angle of other portions, so that the pressure resistance strength of the tie rod hole installation region is higher than that of the other regions.

  Comparing the surface that receives the force due to the pressure difference between the constant pressure chamber and the variable pressure chamber at a right angle and the surface that receives the force at an angle, the surface that receives the force at an angle is more easily tolerated by the load. Due to the same reasoning, the pressure resistance strength of the tie rod hole installation region where the slope angle is increased is increased, so that it is possible to avoid the increase in the number of molding steps by reducing the thickness without increasing the drawing amount of the pressure plate.

  In addition, when the slope angle of each circumferential portion of the umbrella-shaped portion is smoothly changed from the other region toward the tie rod hole installation region, useless stress concentration portions (step portions) are formed in the pressure plate. Therefore, it is not necessary to take measures to strengthen the stress concentration part.

  Also, the pressure plate has an umbrella-shaped portion with a two-stage aperture shape and a tie rod hole is provided in the inner diameter-side umbrella-shaped portion, and only the inner-diameter-side umbrella-shaped portion has different slope angles in the tie rod hole installation region and other regions. The axial dimension of the pressure plate and booster shell can be kept small, and the outer diameter side umbrella-shaped part has the same shape (same angle of slope) in the entire circumferential direction, so the support of the radially outer part of the diaphragm is stable. The performance is not impaired and the overall strength of the pressure plate is not reduced.

It is sectional drawing which shows an example of the negative pressure type booster of this invention. It is an end view of the pressure plate employ | adopted as the negative pressure type booster of FIG. It is sectional drawing along the III-III line of FIG.

  Embodiments of a negative pressure booster according to the present invention will be described below with reference to FIGS.

  The negative pressure type booster 1 shown in FIG. 1 is a tie rod type in which a master cylinder MC is fixed to a booster shell 2 by a tie rod 6.

  The illustrated tie rod type negative pressure booster 1 includes a booster shell 2, a power piston 10, an input rod 3, an output rod 4, a return spring 5 for returning the power piston 10, and two tie rods 6. Configured.

  The booster shell 2 includes a front shell 2a and a rear shell 2b. The front shell 2a has a suction port 19 connected to the air supply manifold of the car engine.

  The power piston 10 is formed by combining a partition member 13 including a pressure plate 11 and a diaphragm 12, and a valve piston 16 having a negative pressure valve 14 and an atmospheric valve 15 therein.

  The interior of the booster shell 2 is divided into a constant pressure chamber 7 and a variable pressure chamber 8 by the partition member 13 of the power piston 10.

  The negative pressure valve 14 is disposed in a passage that allows the constant pressure chamber 7 and the variable pressure chamber 8 to communicate with each other, and opens and closes the passage. The atmospheric valve 15 is disposed in a passage that connects the variable pressure chamber 8 to the outside, and opens and closes the passage.

  The input rod 3 is inserted into the valve piston 16, and when the input rod 3 is pushed by the driver's brake operation, the valve body of the negative pressure valve 14 comes into contact with the valve seat, the negative pressure valve 14 is closed, and the constant pressure chamber 7 is transformed. The room 8 is disconnected.

  Further, when the input rod 3 is further pushed, the valve body of the atmospheric valve 15 is separated from the valve seat, the atmospheric valve 15 is opened, and the atmosphere flows into the variable pressure chamber 8.

  As a result, a pressure difference is generated between the constant pressure chamber 7 and the variable pressure chamber 8, and the power piston 10 receiving the pressure difference is propelled, and the thrust (force amplified according to the brake operation force) is transmitted via the output rod 4. The master cylinder MC is transmitted to the master cylinder MC. Such an operating mechanism is the same as that of a conventional negative pressure booster.

  The pressure plate 11 of the power piston 10 is drawn, and, as shown in FIGS. 2 and 3, between the central hole 11a to which the valve piston 16 is fixed and the radially outer end, as described above. The two-stage aperture-shaped umbrella-shaped portion 17 is provided.

  The umbrella-shaped portion 17 includes an inner-diameter-side umbrella-shaped portion 17a, an inner-diameter-side umbrella-shaped portion, and an outer-diameter-side umbrella-shaped portion 17b that surrounds the outer periphery of the inner-diameter-side umbrella-shaped portion 17a. A number of tie rod holes 18 are provided.

  There is a return portion 17c between the radially outer end of the inner diameter umbrella portion 17a and the radially inner end of the outer diameter umbrella portion 17b, and the diameter of the outer diameter umbrella portion 17b is determined by the installation of the return portion 17c. The inner end position in the direction is retracted in a direction to make the diaphragm of the pressure plate 11 shallower than the outer end position in the radial direction of the inner diameter umbrella-shaped portion 17a.

  The tie rod 6 is airtightly inserted through a tie rod hole 9 provided in each of the front shell 2 a and the rear shell 2 b and a tie rod hole 18 provided in the pressure plate 11.

  The tie rod 6 is arranged on a straight line passing through the center of the booster shell 2, and the master cylinder MC is fixed to the booster shell 2 using the tie rod 6 as a fastener. The tie rod 6 is also used to fix the booster shell 2 to the vehicle body of the vehicle in combination with a mounting bolt 20 (see FIG. 1) for fixing the rear shell 2b.

  The two tie rod holes 18 provided in the pressure plate 11 are arranged such that a straight line L1 (see FIG. 2) connecting the centers of the holes passes through the center of the pressure plate 11.

  Further, the illustrated pressure plate 11 divides the inner diameter side umbrella-shaped portion 17a into a tie rod hole installation area A (see FIG. 2) in which the tie rod hole 18 is formed and another area B (also see FIG. 2). The slope angle α1 (see FIG. 3) of the installation area A is made larger than the slope angle α2 of the other areas B.

  Here, the slope angle changes from CP1 to CP2, where the slope angle change point on the other region B side is CP1, and the slope angle change point on the tie rod hole installation region A side set near the tie rod hole 18 is CP2. The slope angle is smoothly changed toward the front.

  The illustrated pressure plate 11 has a slope angle change point CP1 on the other region B side slightly from the straight line L1 connecting the centers of the two tie rod holes 18 to the tie rod hole installation region A side from the straight line L2 orthogonal to the plate center. Although it is in a biased position, the slope angle changing point CP1 on the other region B side may be on the straight line L2.

  By setting the slope angle change point CP1 at a position appropriately separated from the slope angle change point CP2 on the tie rod hole installation region side as shown in FIG. 2, the slope angle change between CP1 and CP2 is smooth. Thus, it is avoided that a step portion having a sudden height change that easily causes stress concentration on the inner diameter side umbrella-shaped portion 17a is created. The pressure plate 11 that does not have a step portion with a sudden change in height can further reduce the thickness.

  The thickness of the pressure plate 11 and the size of the slope angles α1, α2 are set to a thickness and size that meet the specifications of the negative pressure booster.

  The diaphragm 12 is formed in the same shape as the umbrella-shaped portion at the portion supported by the umbrella-shaped portion of the pressure plate 11 to improve the adhesion of the diaphragm 12 to the surface of the umbrella-shaped portion on the variable pressure chamber side. The same durability as the pressure booster is ensured.

  As described above, according to the present invention, the pressure angle strength of the tie rod hole installation region is increased by increasing the slope angle of the tie rod hole installation region, which tends to decrease the strength of the pressure plate, as compared with other regions. Thus, it is possible to reduce the thickness of the pressure plate without increasing the amount of drawing of the pressure plate.

  For example, in the case of a 10.5 inch negative pressure booster that employs SPC-270 (cold rolled steel plate) as the material of the pressure plate, the thickness of the pressure plate was conventionally about 1.2 mm. In the negative pressure type booster of the invention, even if the pressure plate was made as thin as 0.8 mm, it was possible to secure the same strength as that of the conventional product having the same drawing amount.

  Further, since there is no increase in the amount of drawing, pressure plate molding can be performed with the same number of steps as the conventional product, and good productivity can be secured.

DESCRIPTION OF SYMBOLS 1 Negative pressure type booster 2 Booster shell 2a Front shell 2b Rear shell 3 Input rod 4 Output rod 5 Return spring 6 Tie rod 7 Constant pressure chamber 8 Variable pressure chamber 9 Tie rod hole 10 Power piston 11 Pressure plate 11a Center hole 12 Diaphragm 13 Partition member 14 Negative pressure valve 15 Air valve 16 Valve piston 17 Umbrella portion 17a Inner diameter side umbrella portion 17b Outer diameter side umbrella shape portion 17c Return portion 18 Tie rod hole 19 Suction port 20 Mounting bolt MC Master cylinder A Tie rod hole installation region B Other region α1 Slope angle α2 of the tie rod hole installation region Slope angle CP1 of other region Slope angle change point CP2 of other region side Slope angle change point L1 of tie rod hole installation region side Straight line L2 connecting the two tie rod hole centers of the pressure plate A straight line orthogonal to the straight line L1

Claims (3)

The partition member of the power piston that partitions the inside of the booster shell into a constant pressure chamber and a variable pressure chamber is composed of a pressure plate and a diaphragm,
The pressure plate has an umbrella-shaped portion inclined with respect to a line orthogonal to the central axis between an inner diameter side and an outer diameter side that are drawn and connected to the valve piston,
Tie rods that fasten the master cylinder to the booster shell are inserted airtightly into two tie rod holes respectively provided in the umbrella-shaped portion of the booster shell and the pressure plate,
In the negative pressure type booster, the tie rod hole is arranged so that a straight line connecting the hole centers of the two holes passes through the center of the pressure plate.
Regarding the slope angle of the umbrella-shaped portion of the pressure plate, the slope angle of the tie rod hole installation region is larger than the slope angle of other regions, and the slope angle of each circumferential portion of the umbrella-shaped portion of the pressure plate is A negative pressure type booster characterized in that it is smoothly changed from the other region toward the tie rod hole installation region . The slope angle change point on the tie rod hole installation area side is arranged at a position close to the tie rod hole,
The slope angle changing point on the other region side is a straight line orthogonal to the straight line connecting the centers of the two tie rod holes provided in the pressure plate at the center of the pressure plate,
Or, the negative pressure booster according to claim 1 disposed therefrom at a position offset to the tie-rod hole installation region side. The umbrella-shaped portion of the pressure plate is composed of an inner-diameter-side umbrella-shaped portion and an outer-diameter-side umbrella-shaped portion surrounding the outer periphery of the inner-diameter-side umbrella-shaped portion, and the radially outer end of the inner-diameter-side umbrella-shaped portion and the outer A bending return portion is provided between the radially inner ends of the radial umbrella-shaped portions so that the radially inner end position of the outer-diameter umbrella-shaped portion is more narrow than the radially outer end position of the radially inner umbrella-shaped portion. is retracted in the direction of a shallow, the tie rod holes a provided only for the inside diameter-side cone-shaped part in the tie rod hole installation region and claim 1 or 2 with different slope angles of the other regions in the inner diameter side cone-shaped part The negative pressure type booster described.

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