JPS58191333A - Automatic adjusting device for hydraulic operating type brake - Google Patents

Abstract

PURPOSE:To prevent any adverse influence on a friction joint between a clutch body and a clutch surface by damage to a sealing member, by installing an air reservoir extending upward from a bag cell in the inner part of a clutch hole of an automatic adjusing device inside a wheel cylinder. CONSTITUTION:With the progress of wear in a lining, if a piston 6 is moved outward, an adjusting nut 16 impinges on a contact surface 15 and moves together with the piston 6 by the force of spring 17 whereby a clutch body 20 separates from its surface via an adjusting rod 18 and thus adjustment takes place as the clutch body 20 rotates. When powerful braking is under way, the clutch body 20 fails to separate from a clutch surface 22 so that no adjustment can be achieved. In addition, even if hydraulic fluid in a hydraulic chamber 5 leaks in a bag cell 24 by damage to a sealing member 23, air inside the bag cell 24 is pushed to an upward air reservoir 25 whereby it does not flow to the hydraulic chamber 5 at all so that friction joint motions of the clutch body 20 are normally performed by means of expansion and contraction of the air kept in the air reservoir 25.

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, first and second members defining a hydraulic chamber of a wheel cylinder are arranged so as to be relatively non-rotatable and relatively slidable,
In a hydraulically operated brake in which a brake such as a brake shoe is actuated by the separating action of the two members due to the hydraulic pressure supplied to the hydraulic chamber, the wear of the brake is automatically compensated for and the brake is actuated. The present invention relates to an automatic adjustment device that maintains a constant gap and always performs braking reliably with a predetermined amount of operation of a brake operator such as a brake pedal.

As an automatic adjustment device, the present applicant has proposed an adjustment nut that is non-rotatably supported by one of the first and second members and that abuts a contact surface provided on the one member in a separable manner. a spring that biases the adjusting nut toward the contact side with the abutment surface; an adjusting rod that is screwed into the adjusting nut via a quick screw; a clutch body rotatably fitted into a clutch hole provided in the other member of the first and second members and cooperating with a clutch surface formed on the inner wall of the clutch hole; The clutch body includes a sealing member that isolates the clutch surface from the hydraulic chamber, and the clutch body is activated when the clutch surface receives a thrust in the direction 5 due to hydraulic pressure of a certain value or more in the hydraulic chamber, and when the brake element is returned. A device has already been proposed that frictionally connects with the clutch surface when it receives thrust toward the clutch surface by a spring. This automatic adjustment device prevents over-adjustment due to elastic deformation of each part of the brake during strong braking when the oil pressure in the hydraulic chamber is increased above a predetermined value, thereby preventing the brake from dragging due to over-adjustment. Moreover, it has the advantage that the device can be compactly accommodated in the hydraulic chamber, and the movable parts of the device can be lubricated by the hydraulic oil in the hydraulic chamber. However, in this automatic adjustment device, in the unlikely event that the sealing member is damaged and the hydraulic oil in the hydraulic chamber leaks to the clutch surface side of the clutch hole, it is necessary to There is a risk that the hydraulic oil will become full and prevent the frictional connection of the clutch body to the clutch surface.

An object of the present invention is to provide the automatic adjustment device that eliminates such inconveniences, and is characterized in that an air reservoir is provided that extends upward from the bag chamber at the back of the clutch hole. do.

Embodiments of the present invention will be described below with reference to the drawings.

First, FIG. 1 shows a first embodiment in which the present invention is applied to a two-leading-shuttle drum brake for an automobile.
A pair of left and right wheel cylinders 2゜21 and a pair of upper and lower brake shoes 3, 3' are arranged symmetrically around the center of the back plate 1 on the inner surface of the back plate 1, which is fixed to the vehicle body. The brake drum that surrounds 3, 3' and rotates with the wheels is not shown.

Each of the wheel cylinders 2 and 2' is composed of a cylinder body 4 having a cylinder hole 4α with only one end open, and a piston 6 that slides into the cylinder hole 4a to define a hydraulic chamber 5. The main body 4 is fixed to the back plate 1 with bolts 7 and nuts 8. Engagement grooves 9 and 9' are formed in the outer ends of the cylinder body 4 and the piston 6, respectively, and the corresponding ends of the brake shoes 3 and 3' are engaged with these grooves 9 and 9/, respectively. Return springs 10 and 10' are tensioned between the brake shoes 3 and 3' to maintain the engagement and bias the brake shoes 3 and 3' in the direction of contraction. Due to the engagement of the groove 9°91 with the brake shoes 3, 3', the cylinder/body 4
Relative rotation between the piston 6 and the piston 6 is prevented.

The left wheel cylinder 2 1u11 is provided with a hydraulic pressure introduction port 11 for introducing the output hydraulic pressure of a brake master cylinder (not shown) into its hydraulic chamber 5, and between both wheel cylinders 2.2', the left wheel cylinder 2. A communication pipe 12 is connected to supply the hydraulic pressure introduced into the wheel cylinder 2 also to the right wheel cylinder 2'.

The automatic adjustment device A of the present invention is provided in the hydraulic chambers 5 of both wheel cylinders 2 and 2', and since these have the same structure, only the automatic adjustment device A in the left wheel cylinder 2 will be described in detail below. Explain.

A stepped hole consisting of a large-diameter hole 13 and a small-diameter hole 14 is provided on the inner end surface of the piston 6, and the stepped portion of the stepped hole is formed into a conical abutment surface 15. An adjustment nut 16 that abuts the contact surface 15 in a separable manner is slid into the large diameter hole 13, and the base end of a spring 1T that presses the adjustment nut 16 toward the contact surface 15 is fixed to the piston 6. The spring IT has a function of holding the adjustment nut 16 against the contact surface 15 while also having a function of preventing rotation of the adjustment nut 16 due to the frictional engagement or the uneven engagement between the spring 17 and the adjustment nut 16.

An adjustment rod 18 is screwed into the center of the adjustment nut 16 through a quick screw 19 so as to pass through the adjustment nut 16, and one end thereof is received in the small diameter hole 14. The threaded joint between the adjustment lever 16 and the adjustment rod 18 has an axial direction corresponding to the appropriate operating clearance between each brake shoe 3, 3', that is, the appropriate clearance between each brake shoe 3, 3' and a brake drum (not shown). There is a clearance, and the large diameter hole 13 and the small diameter hole 14 are always in communication through this clearance.

Therefore, the hydraulic pressure introduced into the hydraulic chamber 5 acts even on the adjustment rod 18 within the small diameter hole 14.

A clutch body 20 is integrally formed at the other end of the adjustment rod 18, and this clutch body 20 is rotatably fitted into a bag-shaped clutch hole 21 provided in the inner end wall of the cylinder body 4. , facing a conical clutch surface 22 formed on the back wall of the clutch hole 21. A sealing member 23 is fitted into the clutch hole 21 to prevent the hydraulic pressure in the hydraulic chamber 5 from acting on the clutch surface 22 .

A bag chamber 24 is defined by the tip of the clutch body 20 at the end of the row of the clutch hole 210, and an air reservoir 25 extending upward from the bag chamber 24 is provided in the clutch body 20.

In the illustrated example, an air reservoir 25' extending downward from the bag chamber 24 is further provided. In this way, even if this wheel cylinder 2 is arranged with the piston 6 facing downward like the right wheel cylinder 2', the bag chamber 24
This can be secured by the air reservoir h; 25' extending upward from the wheel cylinders 25', and therefore there is an advantage that the structure of both wheel cylinders 2, 2' can be made common.

Next, to explain the operation of this embodiment, in order to perform braking,
If a brake mask cylinder (not shown) is operated and its output hydraulic pressure is supplied to the hydraulic chamber 5 of the upper wheel cylinder 2, the hydraulic pressure will also be supplied to the lower wheel cylinder 2' via the communication pipe 12. These oil pressures cause the pistons 6 of each wheel cylinder 2, 2' to move outward, expand the corresponding brake shoes 3, 3', and bring them into pressure contact with the inner peripheral surface of a brake drum (not shown). It is possible to add braking force to the

During this braking, the hydraulic pressure in the hydraulic chamber 5 acts equally on both end faces of the adjusting nut 16, so it does not exert any thrust on the clutch body 20. A thrust with a value multiplied by the above-mentioned oil pressure is applied to the clutch surface 22, and this thrust determines the frictional coupling force between the clutch body 20 and the clutch surface.

By the way, in a normal braking state, the hydraulic pressure in the hydraulic chamber 5 is relatively low (therefore, the frictional coupling force between the clutch body 20 and the clutch surface 22 is relatively small, so the brake shoes 3,
When the piston 6 moves further outward due to wear of the lining 3', the adjusting nut 16 moves together with the piston 6 while maintaining the contact state with the contact surface 15 by the elastic force of the spring 17. The clutch body 20 is separated from the clutch surface 22 by means of the adjusting rod 18 against the thrust. When the clutch body 20 separates from the clutch surface 22, the clutch body 2
0 moves toward the clutch surface 22 while being screwed against the non-rotatable adjusting nut 16 by the thrust, and engages the clutch surface 22 again.

During this time, the air in the 9-bag chamber 24 and the air reservoirs 25 and 25' is
Since the clutch body 20 expands and contracts as the clutch body 20 moves forward and backward, it does not interfere with the engagement and disengagement of the clutch body 20 with respect to the clutch surface 22 in any way.

In this way, a self-adjusting action takes place which compensates for the wear of the linings of the brake shoes 3.3'.

At this point, the brake must be released (by reducing the pressure inside the hydraulic chamber 5, the brake shoes 3, 3' will contract under the force of the return springs 10, 10'; acts on the clutch body 20 as a thrust toward the clutch surface 22 via the piston 6, the adjustment nut 16, and the adjustment rod 18, whereby the clutch body 20 is frictionally coupled to the clutch surface 22 and cannot rotate. , the relative rotation between the adjusting nut 16 and the adjusting rod 18 is also disabled, so the piston 6 and the adjusting nut 16 are
The stroke of each brake shoe 3,
An appropriate gap corresponding to the above-mentioned play is created between the lining 1 and the inner circumferential surface of the brake drum.

In addition, when strong braking is performed, the oil pressure in the hydraulic chamber 5 must rise to a predetermined value that causes elastic deformation of the brake shoes 3, 3', brake drum, etc., as described above. When the automatic adjustment action is performed and the oil pressure exceeds the predetermined value, the thrust due to the oil pressure of the clutch body 20 increases and the clutch body 20 is held in a state of frictional engagement with the clutch surface 22, so that the clutch body 20 and adjustment rod 1
8 becomes unable to rotate. Therefore, since the adjusting nut 16, which is originally non-rotatable, is fastened on the adjusting rod 18, when the piston 6 moves further outward due to elastic deformation of the brake drum, etc., the contact surface 15 of the piston 6 separates from the adjusting nut 16. become. In this way, the automatic adjustment effect is stopped.

Next, if the hydraulic oil in the hydraulic chamber 5 leaks into the bag chamber 24 due to damage to the handle member 23, the air in the bag chamber 24 is naturally pushed upward into the air reservoir 25, and the hydraulic oil in the hydraulic chamber 5 leaks into the bag chamber 24.
It does not flow backwards. Therefore, the air reservoir 25 is not filled with hydraulic oil (the air reservoir 25 can always hold air), so that when a thrust is applied to the clutch body 20 in the direction of the clutch surface 22, Due to the expansion and contraction of the air held in the air reservoir 25, the clutch body 20 is normally engaged and disengaged from the clutch surface 22.

Figure 2j shows a second embodiment of the present invention.
In the wheel cylinder 102 of the type including a horizontally placed cylinder body 104 and a pair of left and right pistons 106, 106' facing each other with the hydraulic chamber 5 in between, an automatic adjustment device is installed between the pistons 106, 106'. constitutes 1,
The air reservoir 125 diagonally upward from the bag chamber 24 is connected to the piston 10.
6, an air reservoir 125' extending diagonally downward from the bag chamber 24 and an air reservoir 1 extending horizontally from the bag chamber 24 are provided.
25" are provided on the piston 106 and the clutch body 20, respectively.

In this way, by providing filter air reservoirs 125, 125', and 125'' extending in three vertical directions from the bag chamber 24, no matter how the wheel cylinder 102 is arranged, such as horizontally, vertically, diagonally, etc. , those air reservoirs 125, 125'
, 125'' can always be made into seven-direction air reservoirs, which is convenient and has a wide range of applications.

In FIG. 2, members corresponding to those in FIG. i1 are given the same reference numbers.

As described above, according to the present invention, in the automatic adjustment device configured between the first and second members defining the hydraulic chamber of the wheel cylinder, the air reservoir extends upward from the bag chamber at the back of the clutch hole. Even if the hydraulic oil in the hydraulic chamber leaks to the clutch surface side due to damage to the sealing member, the air reservoir will always have enough air to enable the clutch body to engage and disengage from the clutch surface. is ensured, and there is no risk that it will interfere with the automatic adjustment function.

[Brief explanation of drawings]

Fig. i1 is a longitudinal sectional overall front view of a main part of a brake showing a first embodiment of the present invention, and Fig. 2 is a longitudinal partial front view of a main part of a brake showing a second embodiment thereof. 2.2/... wheel cylinder, 3, 3/... brake/knee, 4... cylinder body (first member), 5...
... Hydraulic chamber, 6... Piston (second member), 10,
10'... Return spring, 15... Contact surface, 16...
Adjustment nut, 17... Spring, 18... Adjustment rod, 19
... Quick screw, 20 ... Clutch body, 21 ... Clutch hole, 22 ... Clutch surface, 23 ... Seal member, 24 ... Bag chamber, 25 ... Upward air reservoir, 102・
...Wheel cylinder, 106...Piston (first member), 106'...Piston (second member), 125...
・Air reservoir facing L, A...Automatic adjustment device patent applicant
Nissin Kogyo Co., Ltd. 18

Claims (1)

[Claims] The first and second members defining the hydraulic chamber of the wheel cylinder are disposed so as to be non-rotatable and slidable relative to each other, and the brake shoes etc. are braked by the separating action of the two members by the hydraulic pressure supplied to the hydraulic chamber. An automatic adjustment device for a hydraulically operated brake configured to actuate a hydraulic brake, wherein the device is non-rotatably supported by one of the first and second members and is spaced apart from a contact surface provided on the one member. An adjusting nut that can come into contact with the adjusting nut, a spring that biases the adjusting nut toward the contact side with the abutting surface, an adjusting rod that is screwed into the adjusting nut via a quick screw, and one end of the adjusting rod. a clutch body fixedly attached to the body and rotatably fitted in a clutch hole provided in the other of the first and second members, the clutch body cooperating with a clutch surface formed on the inner wall of the clutch hole; The clutch body includes a sealing member fitted into the other member to isolate the clutch surface and the hydraulic chamber, and the clutch body receives thrust toward the clutch surface due to hydraulic pressure of a certain value or more in the hydraulic chamber. and an air pocket extending upward from a bag chamber at the back of the clutch hole. An automatic adjustment device for a hydraulically operated brake, characterized in that: is provided on the other member or the clutch body.