CN219325899U - Wire-pulling type oil pressure drum brake - Google Patents

Abstract

The utility model discloses a wire-pulling type oil pressure drum brake, which comprises: a brake block rotating around its own rotation axis; the resetting device is connected with the brake block and used for rotationally resetting the brake block to a position separated from the brake drum around the shaft; the lower pump system is characterized in that a lower pump piston of the lower pump system is connected with the brake block and is used for pushing the brake block to a position combined with the brake drum in a rotating way around a shaft; the upper pump system is connected with the brake pull wire, is connected with the lower pump system through a pipeline, and is used for converting the braking force of the brake pull wire into oil pressure and transmitting the oil pressure to the lower pump piston through the pipeline; compared with the prior art, the brake has better hand feeling, and the brake cable does not need to be adjusted.

Description

Wire-pulling type oil pressure drum brake

Technical Field

The application belongs to the technical field of braking, and particularly relates to improvement of drum braking.

Background

The drum brake is high in reliability and safety, so that the tire is not easy to lock, and the drum brake is often used on electric scooters and electric vehicles. During braking, the two brake blocks are pushed to the inner ring (brake drum) of the hub to generate friction force so as to inhibit the rotation of the tire, thereby achieving the purpose of braking.

However, the existing drum brake mostly adopts a mechanical means of pulling wires, the braking performance is poor, and a handle needs to apply a great force during braking, so that the hand feeling is uncomfortable. After the brake block is worn, a professional is required to adjust and adapt to the travel difference of the worn brake block so as to achieve the optimal performance.

The prior art therefore has two problems:

a. most of drum brakes in the market are mechanical, the braking performance is poor, a great force needs to be applied to a handle during braking, and the comfort is poor.

b. The user wears the brake block after the service time, needs to manually adjust the brake cable, guarantees the brake performance, uses inconveniently, and after-sale maintenance cost is high.

Disclosure of Invention

The purpose of the utility model is that: 1. in order to solve the problem that the brake operation performance of the brake cable pulling and drum braking is poor (large application is needed), the brake comfort is poor 2. The drum braking which does not need to adjust a brake cable is provided, and the maintenance cost is reduced.

The utility model provides a wire-pulling type oil pressure drum brake, which comprises the following components:

a brake block rotating around its own rotation axis;

the resetting device is connected with the brake block and used for rotationally resetting the brake block to a position separated from the brake drum around the shaft;

the lower pump system is characterized in that a lower pump piston of the lower pump system is connected with the brake block and is used for pushing the brake block to a position combined with the brake drum in a rotating way around a shaft;

the upper pump system is connected with the brake pull wire, is connected with the lower pump system through a pipeline, and is used for converting the braking force of the brake pull wire into oil pressure and transmitting the oil pressure to the lower pump piston through the pipeline.

In a preferred embodiment of the present application, the brake blocks include a first brake block and a second brake block; the rotating shaft is fixed at the first ends of the first brake block and the second brake block, and the lower pump piston is matched and connected with the second ends of the first brake block and the second brake block.

In a preferred embodiment of the present application, the lower pump piston comprises a first piston and a second piston; the first piston and the second piston comprise a piston body arranged in the lower pump cylinder and a sealing sleeve arranged between the piston body and the cylinder wall.

In a preferred embodiment of the present application, the first and second pistons include raised contact surfaces, the contact surfaces of the first and second pistons mating.

In a preferred embodiment of the present application, the first piston and the second piston are disposed in the same lower pump cylinder, and the lower pump cylinder is connected to the upper pump system through a pipe.

In a preferred embodiment of the present application, the upper pump cylinder and the lower pump cylinder of the upper pump system are integrally structured with a drum brake end cover, and the pipe is a through hole extending along a straight line in the drum brake end cover and connecting the upper pump cylinder and the lower pump cylinder.

In a preferred embodiment of the present application, the upper pumping system includes an upper pumping piston disposed in an upper pumping cylinder, and a bellow connected to the upper pumping cylinder through a compensating hole.

In a preferred embodiment of the present application, the first opening of the compensating bore is disposed at a location past which the upper pump piston moves.

In a preferred embodiment of the present application, hydraulic oil in the lower pump cylinder flows into the auxiliary oil tank through the compensation hole before the upper pump piston exceeds the first opening during braking; meanwhile, hydraulic oil enters the lower pump cylinder through a pipeline to push the lower pump piston and the brake block to form a compensating pre-brake action.

In a preferred embodiment of the present application, after the upper pump piston exceeds the first opening during braking, the upper pump piston seals the compensation hole, and the hydraulic oil enters the lower pump cylinder through the pipeline to push the lower pump piston and the brake block to form a braking action.

Compared with the prior art, the hydraulic drum brake has the technical progress in two aspects, and the hydraulic drum brake pad is driven by oil pressure, so that the braking force required by a user during operation is reduced by utilizing the hydraulic braking force amplification principle, and the brake hand feeling and the braking force are improved. Because the auxiliary oil tank is connected with the upper pump oil cylinder through the compensation hole, the hydraulic oil automatically compensates the stroke which is increased after the brake block is worn, so that the brake block is not required to be worn

Drawings

Fig. 1 is a schematic diagram of the overall structure of the wire-pulling oil pressure drum brake of the present application.

Fig. 2 is a schematic diagram of a brake structure of a wire pulling oil pressure drum of the present application.

Fig. 3 is a schematic diagram of an exploded structure of an upper pump piston of a wire-pulling oil pressure drum brake of the present application.

Fig. 4 is a schematic diagram of a first sealing plug structure of the wire pulling oil pressure drum brake of the present application.

Fig. 5 is a sectional view of the wire pulling oil pressure drum brake of the present application along the direction A-A in fig. 1.

Fig. 6 is a schematic diagram of an exploded structure of a brake block of a wire pulling oil pressure drum brake of the present application.

Fig. 7 is a schematic diagram of an exploded structure of a brake block of a wire pulling oil pressure drum brake of the present application.

Fig. 8 is a schematic perspective view of a lower pump piston of the present application.

Fig. 9 is a side view of a brake shoe and pump down cylinder of the line pull hydraulic drum brake of the present application.

Detailed Description

The following technical solutions of the present application are further described in detail with reference to the accompanying drawings, so as to help those skilled in the art understand the technical solutions of the present application, and the embodiments described in the present application are preferred implementations of the present application, and do not represent limitations on the protection scope of the present application, which should be controlled by the claims.

Please refer to fig. 1 and 2, which illustrate a schematic diagram of a pull-wire hydraulic drum brake 100. It comprises the following steps: a brake block 700 rotated about its own rotation axis 701; a resetting device 714 connected to the brake block 700 for pivotally resetting the brake block 700 to a position separated from a brake drum (not shown); a lower pump system 900, a lower pump piston 901 of the lower pump system 900 (shown in fig. 8 and 9) is connected to the brake block 700 for rotatably pushing the brake block 700 around the shaft 701 to a position where it is coupled with the brake drum; the upper pump system 300 is connected to the brake cable, is connected to the lower pump system 900 through a pipe 350, and converts the braking force of the brake cable into an oil pressure and transmits the oil pressure to the lower pump piston 901 through the pipe 350.

The upper and lower pumping systems 300 and 900 operate to convert the wire-pull brake into an oil pressure brake that pushes the brake shoe 700 to rotate. The hydraulic braking system can amplify braking force by utilizing a hydraulic amplification principle (Pascal principle), so that a user only needs smaller braking force, and the user has smaller operation hand feeling than the braking force needed by pulling a brake, and has lighter operation hand feeling.

With continued reference to fig. 1 and 2, only the drum brake end cap 101 is shown in this application, as well as the brake blocks 700, associated components, upper pump system 300, lower pump system 900, rocker arm pushrod 200 secured to the drum brake end cap 101. The brake drum (or hub), axle, bearing, etc. structures known to those skilled in the art in the drum brake are omitted, and when those skilled in the art see the present application, the present application and its known techniques can be combined to form a complete drum brake structure, or hub, or bicycle, or electric vehicle, etc. embodiments.

The brake drum end cap 101 is used to secure the structure of the oil pressure drum brake, which acts as a support for the overall system of the present application. The brake drum end cover 101 is an integral structure that integrally provides the upper pump system 300, the lower pump system 900, and the pipe 350 connecting the upper pump system 300 and the lower pump system 900. The brake drum end cap 101 includes a first side 102 and a second side 103, the second side 103 providing a rim 104 for connection to a brake drum (not shown), the rim 104 and the drum cavity formed by the brake drum housing the lower pump system 900, brake pads and their components therein. The drum cavity can prevent adverse environmental factors such as external dust, moisture and the like from affecting the normal operation of the drum brake.

With continued reference to fig. 1 and 2, a rocker arm pushrod 200 is provided on the drum brake end cover 101. The rocker arm pushrod 200 includes a rocker arm 220 pivotally coupled to the brake drum end cap 101, and a pushrod 211 pivotally coupled to the rocker arm 220. The rocker arm is formed by connecting a first connecting plate 201 and a second connecting plate 202 which are identical in structure through the bridging plate 203 arranged between the first connecting plate and the second connecting plate. The first connecting plate 201 and the second connecting plate 202 are respectively provided with a first shaft hole 204 and a second shaft hole 205, the first shaft hole 204 is used for fixing a first rotating shaft 206, and the second shaft hole 205 is used for fixing a second rotating shaft 207. The first rotating shaft 206 includes a shaft sleeve 208 and a fixing screw 209, the shaft sleeve 208 passes through the first shaft hole 204 of the first connecting plate 201 and the second connecting plate 202, the fixing screw 209 passes through the shaft sleeve 208, and the fixing screw 209 is connected with the shaft sleeve 208 to fix the shaft sleeve 208 on the connecting end cover 101. The brake cable pulls the rocker arm 220 to rotate about the first axis 206 when the user operates the hand brake.

A second rotating shaft 207 connected to the push rod 211 is disposed in the second shaft hole 205. A second shaft 207 is fixed in the second shaft hole 205, and a push rod 211 fixing hole 210 is provided on the second shaft 207, and the push rod fixing hole 210 is in accordance with a first end of the push rod 211. The first end of the push rod 211 may be fixed in the push rod 211 fixing hole 210 using a fixing means or may be fixed in the push rod fixing hole 210 using an interference fit. When the rocker arm 220 rotates, the second shaft 207 and the push rod 211 may convert a rotational motion into a horizontal motion to push the upper pump piston 340.

The first connecting plate 201 may further be provided with a stay fixing hole 212, the stay fixing hole 212 may be directly connected with a stay, the stay fixing hole 212 may also be connected with a stay fixing rod, the stay fixing rod is provided with a stay fixing device, the stay fixing device is connected with a stay, and when the stay fixing rod is pulled by a stay, the stay fixing rod and the stay fixing hole rotate relatively.

In a preferred embodiment of the present application, the wire holder includes a set screw and a wire pressing plate, the set screw fixing the wire pressing plate to the wire fixing rod.

Through the rocker arm pushrod 200, a user's brake pull-out action can be converted into a reciprocating action required by a pump piston on an oil pressure brake.

Referring to the structural schematic diagrams of the upper pump piston 340 shown in fig. 2 and 3, wherein fig. 3 omits the drum brake end cover 101, the upper pump cylinder 601, the lower pump system 900, the drum brake block, etc. end covers for brevity

101.

Referring to fig. 3, the push rod 211 includes a ball structure 213, the ball structure 213 is structurally engaged with the ball groove 308 at the end of the upper pumping piston 340, the ball structure 213 ensures that the push rod 211 can be rotated in a vertical direction when the swing arm rotates, and the ball structure 213 pushes the upper pumping piston 340 to move in a horizontal direction. The conversion from the rotational movement of the rocker arm 220 to the horizontal movement is completed by the cooperation of the second rotating shaft 207 of the rocker arm 220 and the ball head structure 213.

Referring to fig. 3 and 6, the ball structure 213 of the push rod 211 is fixed in the upper pump cylinder 352 by a stop washer 309 and a snap spring 310. The clamping groove structure 351 for the clamping spring 310 to stop is arranged in the upper pump cylinder 352, and the diameter of the clamping groove structure 351 is larger than that of the two axial sides of the clamping groove structure 351, so that the clamping spring 310 cannot be separated when being clamped into the clamping groove structure 351. The stop washer 309 rests on the surface of the snap spring 310, and the other side of the stop washer 309 rests on a step 353 of greater diameter than the upper pump cylinder 352. The stopper washer 309 is provided with a stopper hole 311 into which the push rod 211 is inserted, and the stopper hole 311 has a diameter larger than that of the push rod 211 but smaller than that of the ball structure 213, so that the push rod 211 and the upper pump piston 300 are restrained within the upper pump cylinder 352.

Referring to fig. 3, an upper pump piston 300 is included and has a structural schematic diagram of a mating relationship. The center of the upper pump piston 340 comprises a first step 301 and a second step 302, said first step 301 and second step 302 comprising a lubrication groove 303, the lubrication groove 303 containing hydraulic oil to lubricate the sealing plugs (313, 320) and the sliding interface between said first step 301 and second step 302 and the upper pump cylinder 352. The front of the first step 301 comprises a head end 304, the diameter of which head end 304 is smaller than the diameter of the first step 301, the head end 304 comprises a third step 306, which is stopped, the diameter of the third step 306 is also smaller than the diameter of the first step 301, a return spring fixing post 305 is arranged in front of the third step 306, and the spring fixing post 305 is inserted into the hollow core of the return spring 307 when the return spring 307 is fixed. The first sealing plug 320 on the upper pump piston 300 is mounted and fixed behind the third step 306 of the head end 304, the first step 301 and the third step 306 defining the axial position of the first sealing plug 320.

A second sealing plug 313 fixing groove 312 is formed at the other end opposite to the head end 304, the second sealing plug 313 fixing groove 312 is used for installing a second sealing plug 313, the second sealing plug 313 is an annular O-shaped sealing plug, a round table 314 forming the ball-shaped groove is formed at one end adjacent to the fixing groove 312, and the diameter of the round table 314 is smaller than the diameters of the first step 301 and the second step 302. The first step 301, the second step 302, the first sealing plug 320 and the second sealing plug 313 are in direct contact with the inner wall of the upper pump cylinder 352 when the upper pump piston 300 moves within the upper pump cylinder 352.

Reference is made to the other side of the first sealing plug 320 shown in figure 4.

The first sealing plug 320 includes two parts, the first part is a sealing base 321, the second part is a sealing lip 322 disposed on the sealing base 321, the diameter of the sealing lip 322 is larger than that of the sealing base 321, an annular deformation groove 323 is formed between the sealing lip 322 and the sealing base 321, the sealing lip 322 is compressed when entering the upper pump cylinder 352, and the deformation groove 323 can accommodate the compressed sealing lip 322. The deformation groove 323 has various advantages in that a compression space of the sealing lip 322 is reserved to maintain the elasticity of the sealing lip 322; and secondly, the stress of the second sealing device can be reduced, and accelerated aging caused by excessive internal stress of the second sealing device can be avoided. The deformed sealing lip 322 of the third aspect can reduce the sliding friction of the upper pump piston 300; in the fourth aspect, the oil pressure is applied to the sealing lip 322 through the deformation groove 323 against the sealing lip 322 during braking so that the sealing effect is enhanced at the direct connection interface of the sealing lip 322 and the inner wall of the upper pump cylinder 352.

Referring to fig. 2 and 6, a secondary tank 600 is provided in the drum brake end cover 101, and the secondary tank 600 is used for balancing the pressure in the upper pump cylinder 352. The auxiliary fuel tank 600 comprises an opening 601 and a sealing cover 602 arranged on the opening 601 for sealing the opening 601, wherein the sealing cover 602 comprises a sealing gasket, and the sealing cover 602 and the opening 601 can be connected by using a thread structure. When the auxiliary tank 600 is short of oil, the sealing cover 602 can be opened to supplement the oil tank with hydraulic oil. The secondary fuel tank 600 is provided with another sealing opening 601 'and a sealing cover 602', and the two sealing covers 602 have the same structure. The two sealing covers are used for observing the oil level by opening different sealing covers.

The auxiliary oil tank 600 and the upper pump cylinder 352 are connected through the compensation hole 603 and the lubrication hole 607. The compensating hole 603 is arranged at a first distance in the travelling direction of the upper pump piston 340, and the compensating hole 603 is sealed after the travelling of the upper pump piston 340 at the first distance. The first opening 604 of the compensating bore 603 is arranged at a position over which the upper pump piston moves through a stroke. So that the hydraulic oil in the upper pump cylinder 352 flows into the auxiliary oil tank 600 through the compensating hole 603 before the upper pump piston brakes beyond the first opening 601; while the hydraulic oil enters the lower pump cylinder 904 through the conduit 350 to push the lower pump piston 901 and the brake block 700 to form a compensating pre-braking action (the braking process will be described in detail later).

The first opening 607 of the lubrication hole 606 is provided at a position where the movement stroke of the upper pump piston 340 passes, when the upper pump piston 340 is advanced to the second position, the lubrication groove 303 is faced to the lubrication hole 606, and the lubrication oil in the sub-tank 600 flows from the lubrication hole 606 into the lubrication groove 303.

Referring to fig. 5 and 6, an elastic oil bag 500 is disposed in the auxiliary oil tank 600, and the oil bag 500 is hermetically connected with the auxiliary oil tank 600 to form a volume-adjustable cavity 514. The oil bag 500 includes a first end 509 connected to the opening 601 of the auxiliary oil tank 600 in a sealing manner, and a second end 510 extending into the auxiliary oil tank 600, and a sealed cavity 502 capable of elastically expanding and contracting the oil bag 500 is formed from the first end 509 to the second end 510. The first end 509 of the oil bladder 500 includes an annular gasket 513, the annular gasket 513 being coupled to a sealing step 609 at the opening 601 of the second fuel tank 600.

The oil bladder 500 has a generally funnel-shaped cross-section and includes a chamfer 501 at a first end 509 of the oil bladder 500, the chamfer 501 providing a gradual reduction in the cross-sectional thickness of the oil bladder 500 to form a low compressible cavity 502. The first end 509 of the oil bag 500 is provided with a stopper 503 coupled to the inclined surface 501, a supporting surface 504 of the stopper 503 has the same gradient as the first end 509 of the oil bag 500, and is made of a rigid material as the stopper 503, and the supporting surface 504 can prevent the oil bag 500 from being excessively inflated. The stopper 503 includes a vertical surface 505 having a vent 506 at the interface of the vertical surface and the supported surface 504, and is configured to communicate the compressible chamber 502 of the oil bladder 500 with the atmosphere to balance the pressure.

The second end 510 of the oil bladder 500 is a double-layered tongue structure, the middle of which comprises the continuous space forming the compressible cavity 502. The second end 510 body portion of the oil bladder 500 includes two sealed concentric semi-circular walls 511, the two concentric semi-circular walls 511 defining a continuously sealed duckbill-shaped compressible cavity 502. The duckbill-shaped oil bladder 500 has various advantages in that, on the one hand, due to its wide and flat shape, the concentric semicircular outer wall 511 is supported by the inner wall of the auxiliary oil tank 600, and has good elasticity, and can maintain good elasticity after repeated and long-term compression and shrinkage, so that it has good durability. On the other hand, the radial area of the wide side is large, the radial travel of the same expansion volume material is small, and the stress abrasion to the material can be reduced, so that the service life is prolonged.

The stopper 503 further includes a pressing edge 507 for sealing the sealing pad of the first end 509 of the oil bag 500, and a positioning protrusion 508 radially protruding from the pressing edge 507 is included around the pressing edge 507, where the protrusion 508 is disposed in a receiving groove at the threaded opening 601 of the auxiliary oil tank 600. The auxiliary fuel tank 600 further comprises a set screw 520, the set screw 520 is used for fixing the stop member 503, the center of the set screw 520 is provided with a spline vent 521, the spline vent is communicated with the atmosphere, and the air flowing out through the pressure balance hole 521 on the stop member 503 flows out to the atmosphere through the spline vent 521. The spline vent 521 can be matched with a fastening spanner at the same time, so that the rotary installation is convenient.

Referring to fig. 7 and 9, the brake blocks include a first brake block 703 and a second brake block 704; the rotating shaft 701 is fixed at the first ends of the first brake block 703 and the second brake block 704, and the lower pump piston 901 is coupled with the second ends of the first brake block 703 and the second brake block 704.

The first brake shoe 703 includes a first brake shoe 705 and a first friction plate 708 disposed on the first brake shoe 705. The first brake shoe 705 includes an arcuate support plate 710 and a web 711 perpendicular to the support plate. The first end of the first brake shoe 705 includes a first securing hole 712 for mounting the rotor shaft 701, and the first brake shoe 705 includes a return spring 714 securing hole 713 provided in the rib plate.

A rotary shaft 701 is fixed to the drum brake end cover 101. One end of the rotating shaft 701 is connected with a rotating shaft 701 fixing hole 715 on the end cover 101, the rotating shaft 701 fixing hole 715 comprises a convex reinforcing round table 717, the rotating shaft 701 fixing hole 715 is arranged in the round table 717, and the rotating shaft 701 passes through the first fixing hole 712 and a second fixing hole on the second brake block 704 to be connected with the fixing hole 715.

A second end of the first brake shoe 705 opposite the first mounting hole 712 includes a lower pump piston 901 mating block 718, the lower pump piston 901 mating block 718 including a generally triangular cross-section, the mating block 718 including a flat surface that mates with an end surface of the lower pump piston 901.

The second brake shoe 706 has the same structure as the first brake body and will not be described in detail herein.

When a user brakes, the lower pump piston 901 extends outwards to push the first brake shoe 705 and the second brake shoe 706 to rotate around the fixed shaft 701, friction plates of the first brake shoe 705 and friction plates of the second brake shoe 706 simultaneously rub with an inner layer of the brake drum to generate braking force, when the user releases the brake, the brake pump is reset, and the first brake shoe 705 and the second brake shoe 706 rotate around the fixed shaft 701 to reset.

The lower pump piston 901 comprises a first piston 902 and a second piston 903; the first piston 902 and the second piston 903 include a piston body 907 disposed in a lower pump cylinder 904 and a sealing sleeve 905 disposed between the piston body and the cylinder wall.

Referring to fig. 6, 7 and 9, the piston body 907 is hollow and the piston body 907 includes a raised contact surface 906, the contact surfaces of the first and second piston bodies 907 and 908 being mated. The area of the contact surface is smaller than that of the piston body, an annular cavity 909 is formed between the first piston body 907, the second piston body 908 and the wall of the lower pump cylinder 904 when the convex surfaces of the first piston body 907 and the second piston body 908 are matched, the annular cavity 909 is provided with a first opening 608 of the communication pipeline 350 between the lower pump cylinder 904 and the upper pump cylinder 352, and when oil in the upper pump cylinder 352 enters the lower pump cylinder 904, the oil in the annular cavity 909 can push the first piston body 907 and the second piston body 908 simultaneously, so that the first brake block 703 and the second brake block 704 can brake simultaneously.

In this application, the first piston 902 and the second piston 903 are disposed within the same lower pumping cylinder 904, the lower pumping cylinder 904 being connected to the upper pumping system 300 by a conduit 350. It is also conceivable for a person skilled in the art to use two pipes 350 and two cylinders to be connected to the upper pump system 300, respectively, and to arrange the first piston 902 and the second piston 903 in different cylinders, respectively. The pipe 350 is a through hole extending along a straight line in the drum brake end cover 101 and connecting the upper pump cylinder 352 and the lower pump cylinder 904, and the pipe 350 extends in the drum brake end cover 101 obliquely at a certain angle with the vertical direction when viewed from the side view direction E.

The seal housing 905 prevents hydraulic oil from leaking from the lower pump cylinder 904. The seal housing 905 is embedded in a recess in the inner wall of the lower pump cylinder 904. In a preferred embodiment of the present application, the sealing sleeve 905 is an elastic structural member made of a rubber material.

The braking process is further described below in connection with fig. 6, 7, 9.

During normal braking, braking force of a user is transmitted to the rocker arm through the pull wire, the rocker arm converts the braking force into horizontal movement of the upper pump piston, and the upper pump piston moves along the direction B. Hydraulic oil in the lower pump cylinder 904 flows through the compensating bore 603 into the secondary tank 600 before the first sealing plug of the upper pump piston passes beyond the first opening 604 of the compensating bore 603. The pressure generated by the upper pump piston enters the lower pump cylinder 904 through the hydraulic oil pipeline 350 according to the pascal effect, the piston in the lower pump cylinder 904 is pushed by the hydraulic oil, so that the first brake block 703 and the second brake block 704 are opened, when the friction plate of the brake block is in contact with the inner wall of the brake drum, the braking force is not enough to be formed, the lower pump piston 901 is not pushed any more, the upper pump piston continues to move the hydraulic oil to flow back into the auxiliary oil tank 600 through the compensating hole 603, the oil bag 500 in the auxiliary oil tank 600 is compressed and expanded, and the air in the compressible cavity 502 in the oil bag is discharged through the vent hole 506 and the pressure balancing hole 521 until the first sealing plug 320 of the upper pump piston exceeds the compensating hole 603.

When the upper pump piston first sealing plug 320 passes beyond the compensating hole 603, the compensating hole 603 is sealed, all hydraulic oil flows into the lower pump cylinder 904 through the pipe 350, and the lower pump piston 901 is pushed further so that the first brake block 703 and the second brake block 704 further expand the stroke braking force.

It can be seen that a braking force has not been formed before the first sealing plug of the upper pump piston exceeds the compensating hole 603, but the brake block has already traveled a pre-braking stroke, which compensates for the increased gap generated by wear if the friction plate has increased in wear braking gap, pushing the lower pump piston 901 and the brake block to form a compensating pre-braking action. The hydraulic oil is essentially forced into the reservoir 600 before the first sealing plug passes beyond the compensating hole 603 if the brake pad is not worn. Whether the brake pad is worn or not, the brake force is formed after the first sealing plug exceeds the compensation hole 603, the stroke of the brake force and the time point when the brake force is formed are not changed due to the abrasion of the brake pad, and the brake cable does not need to be adjusted.

When the user releases the brake, the upper pump piston is reset under the action of the reset member 307, and returns to the initial position. The movement direction of the upper pump piston 340 is opposite to the direction B, before the first sealing plug of the upper pump piston 340 passes through the compensating hole 603, hydraulic oil in the lower pump cylinder 904 flows back into the upper pump cylinder 352 through the pipeline 350, and at the same time, the lower pump piston 901 is reset, the first brake block 703 and the second brake block 704 are reset under the action of the reset spring 714, and the braking force disappears. After the first sealing plug 520 passes through the compensating hole 603, the oil in the auxiliary oil tank 600 flows back (negative pressure is sucked back) into the upper pump cylinder 352 through the compensating hole 603, and the oil bag in the auxiliary oil tank 600 is restored from the inflated state.

Compared with the prior art, the brake hand feeling is improved, the idle stroke caused by abrasion of the brake block is automatically compensated through the auxiliary oil tank 600 and the upper pump system 300, the brake hand feeling is not changed, and meanwhile, a brake cable does not need to be adjusted. The hydraulic system brakes require less braking force than pure line pull brakes.

Claims (8)

1. A wire-pulling type oil pressure drum brake, comprising:

a brake block rotating around its own rotation axis;

the resetting device is connected with the brake block and used for rotationally resetting the brake block to a position separated from the brake drum around the shaft;

the lower pump system is characterized in that a lower pump piston of the lower pump system is connected with the brake block and is used for pushing the brake block to a position combined with the brake drum in a rotating way around a shaft;

the upper pump system is connected with the brake pull wire, is connected with the lower pump system through a pipeline, and is used for converting the braking force of the brake pull wire into oil pressure and transmitting the oil pressure to the lower pump piston through the pipeline.

2. The wire-pulling type oil pressure drum brake of claim 1, wherein the brake blocks comprise a first brake block and a second brake block; the rotating shaft is fixed at the first ends of the first brake block and the second brake block, and the lower pump piston is matched and connected with the second ends of the first brake block and the second brake block.

3. The wire-pull type oil pressure drum brake of claim 1, wherein the lower pump piston comprises a first piston and a second piston; the first piston and the second piston comprise a piston body arranged in the lower pump cylinder and a sealing sleeve arranged between the piston body and the cylinder wall.

4. A wire-pull type oil pressure drum brake according to claim 3, wherein the first and second pistons include raised contact surfaces, the contact surfaces of the first and second pistons being mated.

5. The brake-by-wire hydraulic drum brake of claim 4, wherein the first piston and the second piston are disposed within a same lower pump cylinder that is connected to the upper pump system by a conduit.

6. The wire-pulling type oil pressure drum brake according to claim 5, wherein the upper pump cylinder and the lower pump cylinder of the upper pump system are of an integrated structure with a drum brake end cover, and the pipeline is a through hole which extends along a straight line in the drum brake end cover and connects the upper pump cylinder and the lower pump cylinder.

7. The brake-by-wire hydraulic drum brake of claim 6, wherein the upper pumping system includes an upper pumping piston disposed in an upper pumping cylinder, and a secondary tank connected to the upper pumping cylinder through a compensating hole.

8. The wire-pull type oil pressure drum brake according to claim 7, wherein the first opening of the compensating hole is provided at a position through which the upper pump piston moves.

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