Hydraulic brake caliper piston/plunger tool

A hydraulic brake caliper piston/plunger tool includes a handle, a barrel with rear and front tubes, and a shaft. The handle is provided therein with a fluid reservoir and a fluid chamber, and pivotally connected with an operation lever having a plunger inserted into the fluid chamber. The shaft is attached with a piston and fitted through the rear tube, the barrel and the front tube. A return spring is fitted around the shaft in a central hole of the barrel, between the piston and the front tube. A front end of the shaft is adapted to be fitted with an accessory for a disc brake. A rear end of the shaft is adapted to be connected with a turning tool. In use, alternately depressing and releasing the operation lever enables fluid to enter the central hole of the barrel to have the piston together with the shaft moved forward.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hydraulic brake caliper piston/plunger tool and, more particularly, to a hydraulic brake caliper piston/plunger tool that can be applied to all sorts of disc brakes to easily push back a piston/plunger of a disc brake into the associated caliper.

2. Description of the Prior Art

Generally, there are two kinds of existing tools being used to facilitate replacing brake shoes of disc brakes. One kind of tool is featured in a threaded rod that can be rotated to enable the piston/plunger of a disc brake to be pushed back into the associate caliper. Another kind of tool employs an unthreaded rod provided with springs to push back a piston/plunger into the associated caliper. However, these tools are either slow or laborious in operation. Furthermore, since disc brakes are different in the structure of their pistons/plungers, i.e. some disc brakes containing threaded pistons/plungers while other disc brakes containing unthreaded pistons/plungers. These tools cannot be applied to all sorts of disc brakes. Thus, there is room for improvement in the structure of the tools.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a hydraulic brake caliper piston/plunger tool, which can solve the disadvantages of conventional tools.

The hydraulic brake caliper piston/plunger tool generally comprises a handle, a barrel, and a shaft. The handle is provided with a fluid reservoir in a lower section thereof and a fluid chamber in a middle section thereof, and pivotally connected with an operation lever at the middle section. The barrel is coaxially assembled with front and rear tubes respectively at two ends thereof, wherein the barrel and the rear tube are mounted at an upper section of the handle. The shaft is fixedly attached with a piston and fitted through the rear tube, the barrel, and the front tube. A return spring is fitted around the shaft in a central hole of the barrel, between the piston and the front tube. A circumferential passage that communicates with the central hole of the barrel is defined between the shaft and the rear tube. A front end of the shaft is adapted to be fitted with an accessory for a disc brake. A rear end of the shaft is adapted to be connected with a turning tool for turning the shaft. A fluid circuit system is provided in the handle such that the fluid chamber is communicated with the fluid reservoir and the circumferential passage. The operation lever is spring-biased and provided with a plunger inserted into the fluid chamber. In use, alternately depressing and releasing the operation lever enables the plunger to force fluid to flow into the central hole of the barrel by way of the fluid circuit system and the circumferential passage, thus pushing the piston together with the shaft to move forward to push back a piston/plunger of a disc brake.

More specifically, the fluid circuit system includes a first fluid feed passage, a second fluid feed passage, and a fluid supply passage. The first fluid feed passage is defined in the middle section of the handle and connected with the fluid chamber. The second fluid feed passage is defined in the upper section of the handle and connected between the first fluid feed passage and an inlet port of the rear tube that communicates with the circumferential passage. The fluid supply passage is defined in the middle section of the handle and connected between the fluid chamber and the fluid reservoir. Furthermore, a first check valve is provided at the fluid supply passage to ensure fluid to unidirectionally flow from the fluid reservoir to the fluid chamber. A second check valve is provided at the first fluid feed passage to ensure fluid to unidirectionally flow from the fluid chamber to the central hole of the barrel. Each of first and second check valves includes a steel ball urged by a compression spring to normally close the corresponding passage.

More specifically, the operation lever is pivotally connected to a post fixed on the middle section of the handle, and a spring is fitted around the plunger, between the handle and the operation lever, to enable the operation lever to return to its original position when releasing the operation lever.

Furthermore, a control valve is provided at the fluid return passage to control to return to the fluid reservoir. The control valve includes a steel ball, and a knob provided with a threaded stem capable of forcing against the steel ball. In use, turning the knob in one direction opens the fluid return passage, while turning the knob in a reverse direction closes the fluid return passage.

The hydraulic brake caliper piston/plunger tool of the present invention is labor-saving and easy to use and can be applied to all sorts of disc brakes containing threaded or unthreaded pistons/plungers, thus saving the tool cost.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To illustrate the objects and advantages of the present invention, a preferred embodiment in conjunction with the accompanying drawings is provided in the following paragraphs.

Referring toFIGS. 1 through 3, a hydraulic brake caliper piston/plunger tool according to one embodiment of the present invention is shown, which generally comprises a handle composed of a middle section1, a lower section4and an upper section5, a barrel7with a rear tube6and a front tube8, and a shaft9. The sections1,4,5of the handle can be joined together by thread means. The middle section1of the handle is provided therein with a fluid chamber10and pivotally connected with an operation lever2, wherein the operation lever2is provided with a plunger21inserted into the fluid chamber10, and a spring22is fitted around the plunger21between the handle and the operation lever2. The lower section4of the handle is provided therein with a fluid reservoir40. The barrel7is coaxially assembled with the front and rear tubes6,8by threads respectively at two ends thereof, wherein the barrel7and the rear tube6are mounted at the upper section5of the handle. The barrel7together with the rear and front tubes6,8is mounted substantially perpendicular to the handle. The shaft9is fixedly attached with a piston71and fitted through the rear tube6, the barrel7and the front tube8, wherein the piston71can be attached to the shaft9by means of a pin710. A return spring72is fitted around the shaft9in a central hole70of the barrel7, between the piston71and the front tube8, wherein a circumferential passage61that communicates with the central hole70of the barrel7is defined between the shaft9and the rear tube6. A front end of the shaft9is formed into a drive lug90to be fitted with an accessory for a disc brake. A rear end of the shaft9is formed into a drive end91with an opening, which can be connected with a turning tool, such as wrenches, so that the shaft9can be rotated. A fluid circuit system, which generally includes a first fluid feed passage15, a second fluid feed passage50, a fluid supply passage11, and a fluid return passage14, is provided in the handle. The first fluid feed passage15is defined in the middle section1of the handle and connected with the fluid chamber10. The second fluid feed passage50is defined in the upper section5of the handle and connected between the first fluid feed passage15and an inlet port60of the rear tube6that communicates with the circumferential passage61. The fluid supply passage11is defined in the middle section1of the handle and connected between the fluid chamber10and the fluid reservoir40. The return fluid passage14is defined in the middle section1of the handle and connected between a communication space16and the fluid reservoir40(seeFIG. 3). In this embodiment, the communication space16, which is located between the middle section1and the upper section5, allows fluid communication between the first fluid feed passage15, the second fluid feed passage50, and the fluid return passage14. A first check valve12, including a first steel ball120and a compression spring121, is provided at the fluid supply passage11to ensure fluid to unidirectionally flow from the fluid reservoir40to the fluid chamber10, wherein the first steel ball120can be urged by the first compression spring121to normally close the fluid supply passage11. A second check valve13, which is provided at the first fluid feed passage15to allow fluid therein to flow in one direction, includes a second steel ball130and a second compression spring131, wherein the second steel ball130can be urged by the second compression spring131to normally close the first fluid feed passage15. More specifically, the operation lever2is connected by a pivot24to a post23fixed on the middle section1of the handle. Depressing the operation lever2allows the fluid contained in the fluid chamber10to flow upwardly to enter the central hole70of the barrel7via the first fluid feed passage15, the second fluid feed passage50, the inlet port60, and the circumferential passage61, so that the shaft9together with the piston can be pushed forward, and at the same time, the return spring72can be compressed. The spring22enables the operation lever2to return to its original position when releasing the operation lever2. Preferably, the plunger21is pivotally connected to the operation lever2through a pin20. A control valve3is provided at the fluid return passage14to control the fluid in contained in the fluid circuit system and the central hole70of the barrel7to return to the fluid reservoir40. More specifically, the control valve3includes a steel ball31, and a knob32provided with a threaded stem30capable of forcing against the steel ball31, wherein the knob32is located outside of the middle section1of the handle. By turning the knob32in one direction, the fluid return passage14can be opened. By turning the knob32in a reverse direction, the fluid return passage14can be closed.

The fluid contained in the fluid reservoir40, the fluid chamber10, the central hole70of the barrel7, and the first and second fluid feed passages15,50, the communication space16, the inlet port60, the circumferential passage61and the fluid return passage14is a chemically inert hydraulic fluid to transmit force and motion.FIG. 2shows the tool of the present invention being filled with the fluid, before it is operated.

In an operation for pushing back an unthreaded piston/plunger into a disc brake caliper (A), as shown inFIG. 7, an accessory can be fitted on the front end of the shaft9. The accessory includes a drive plate (D1), a fixed plate (D2), and a guide rod (D3) fixedly attached to the drive plate (D1) while slidably connected with the fixed plate (D2), wherein the drive plate (D1) is attached to the drive lug90of the shaft9to be in contact with the caliper's piston/plunger, whereas the fixed plate (D2) is fixed over a groove80of the front tube8and abuts against an outboard part of the caliper (A). Next, the operation lever2can be depressed to have the plunger21moved inwardly of the fluid chamber10, as shown inFIG. 4. Under this condition, the first check valve12does not allow fluid to flow from the fluid chamber10to the fluid reservoir40, while the second check valve13allows fluid to flow upwardly from the fluid chamber10. As a result, the fluid contained in the fluid chamber10can be forced by the plunger21to flow through the first and second fluid feed passages15,50, the inlet port60and the circumferential passage61to enter the central hole70of the barrel7to push the piston71together with the shaft9to move forward. As the piston71moves forward, the return spring72can be compressed. When releasing the operation lever2, as shown inFIG. 5, the spring22enables the operation lever2to return to its original position, so that the plunger21can be moved outwardly of the fluid chamber10, thus causing the fluid to experience a vacuum suction force. As a result, the second check valve13can be closed, while the first check valve12can be opened to allow the fluid contained in the fluid reservoir40to flow into the fluid chamber10via the fluid supply passage11. By alternately depressing and releasing the operation lever2for a number of cycles, the shaft9together with the piston71can be forced by fluid to advance to a certain extent, so that the piston/plunger of a disc brake can be pushed back into the associated caliper. It is easy to use the tool. For another type of disc brake caliper (B) containing a threaded piston/plunger, as shown inFIG. 8, another accessory can be used, which includes a drive disk (E1) and a fixed plate (E2), wherein the drive disk (E1) is fixed to the drive lug90of the shaft9, whereas the fixed plate (E2) is fitted over the groove80of the front tube8and abuts against an outboard part of the caliper. For this type of disc brakes, a turning tool (C), such as wrenches, can be used to connect with the drive end91of the shaft9. In use, the turning tool (C) can drive the shaft9to rotate simultaneously while the shaft9is moved forward by the operation lever2, so that the piston/plunger can be screwed into the disc brake caliper. The hydraulic tool is labor-saving and easy to use, and can be applied to disc brakes containing either unthreaded pistons/plungers or threaded pistons/plungers. It is easy to use the tool.

After the piston/plunger has been pushed back into the disc brake caliper, the user may turn the knob32of the control valve3in one direction such that the steel ball31is no longer urged by the stem30, so that the fluid return passage14can be opened (seeFIG. 6), so that the fluid contained in the central hole70of the barrel7can flow into the fluid reservoir40by way of the circumferential passage61, the inlet port60, the second fluid feed passage50, and the fluid return passage14. As the fluid flows back to the fluid reservoir40, the compressed return spring72can force the piston71together with the shaft9to move backward to reach its original position. For a next operation, the control valve3can be turned in a reverse direction to close the fluid return passage14, and in a similar way, a suitable accessory can be employed to have the shaft9moved forward again, with or without a turning tool. It is easy to use the tool.

While the invention has been described with reference to the preferred embodiment above, it should be recognized that the preferred embodiment is given for the purpose of illustration only and is not intended to limit the scope of the present invention and that various modifications and changes, which will be apparent to those skilled in the relevant art, may be made without departing from the scope of the invention.