Motor driven brake system

A motor driven brake system including a parking brake, in particular, a motor driven parking brake system in which a parking brake is implemented using a compact motor and a plurality of disks and friction pads mutually fractionized or released by the compact motor, so that it is possible to reduce operating noise of a solenoid as compared with that of an existing solenoid and to prevent a phenomenon that although a power failure of the compact motor occurs during driving, the braking power of the motor driven brake system is not released.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims under 35 U.S.C. §119(a) the benefit of Korean Patent Application No. 10-2012-0156060 filed Dec. 28, 2012, the entire contents of which are incorporated herein by reference.

BACKGROUND

(a) Technical Field

The present invention relates to a motor driven brake system. More particularly, the present invention relates to a motor driven brake system including a parking brake.

(b) Background Art

A motor driven brake system refers to a next-generation brake system which is able to provide a faster and more precise braking response performance as compared with an existing hydraulic brake system, a more simplified package layout due to removal of hydraulic pipe lines, minimal environment pollution without using brake oil, simple development of efficient application logic, improved collision safety due to removal of a master cylinder and a vacuum booster, and the like.

In a motor driven brake system a brake pad is pressed by converting rotary power transmitted from a motor and a decelerator into linear power using a screw like mechanism. As a result, the motor driven parking brake system obtains braking power. On the contrary, when power is off, the screw like mechanism is unscrewed in the reverse direction by the pressing force of the brake pad, so that the braking power is released.

Because of these features of the motor driven brake system, a separate parking brake apparatus may be combined with the motor driven brake system so that parking braking power can be provided when the power is off. That is, since a separate parking brake in the existing hydraulic brake system more expensive and heavy, a separate parking brake apparatus configured to share motor power for braking with the motor driven brake system may be mounted to the motor driven brake system in an effort to solve these problems.

Hereinafter, the configuration and operation of a conventional motor driven brake system having a parking brake will be described with reference toFIGS. 1 and 2.

InFIGS. 1 and 2, reference numeral100represents a motor driven brake system, and reference numeral200represents a parking brake. The motor driven brake system100includes friction pads104attached in a caliper housing102, and a disk106disposed between the friction pads104so as to be pressed by the friction pads104. A piston108movable forward and backward is installed in a horizontal through aperture of a caliper housing102, and a pressure member110having a screw aperture is integrally installed inside the piston108.

In this case, a reduction gear and an electric motor114having both side shafts are mounted at an inner end portion of the caliper housing102. Here, an outside shaft of the electric motor114is connected by means of the reduction gear to a screw-shaped push rod116inserted and fastened into the screw aperture112of the pressure member110, and an inside shaft is employed as a rotating shaft120having a locking pin118formed on the outer circumferential surface thereof.

Meanwhile, as one configuration of the parking brake200, a parking brake housing202is integrally mounted to an inner surface of the electric motor114, and the rotating shaft120of the electric motor114is rotatably disposed at a central portion of the parking brake housing202.

A solenoid204is mounted on the inner surface of the parking brake housing202, and a horizontal pipe206is disposed between the solenoid204and the rotating shaft120. A sliding disk208in the shape of a vertical plate is integrally formed with the inner end portion of the horizontal pipe206. In this case, as shown in the sectional view taken along line D-D ofFIG. 2, a locking groove212into which the locking pin118of the rotating shaft120is inserted is formed in the inside diameter surface of the horizontal pipe206.

A spring210is disposed between the solenoid204and the sliding disk208to be compressible and expendable. A friction plate214that the sliding disk208frictionally contacts to perform parking braking is attached to the inner wall surface of the parking brake housing202.

A controller220for turning on/off the power supplied to the device is connected to the electric motor114and the solenoid204. Thus, during normal braking, the controller220turns on the electric motor114and simultaneously turns on the solenoid according to a degree to which a brake pedal is pushed.

Subsequently, when the push rod116of the electric motor114performs a standing rotation, the pressure member110fastened to the push rod116performs a rectilinear motion toward a vehicle outer direction. This is because the push rod116is formed in a screw like shape.

Continuously, the piston108integrally formed with the pressure member110presses the friction pads104, and simultaneously, the disk106interposed between the friction pads104is pressed, so that braking is performed during driving. In this case, as power is applied to the solenoid204, the parking brake is released.

That is, when the solenoid204is turned on, the solenoid204pulls the sliding disk208by means of the force from an electromagnet. In this case, the sliding disk208is spaced apart from the friction plate214, so that the parking brake is released the rotating shaft120of the electric motor114becomes rotatable. Simultaneously, the spring210disposed between the solenoid204and the sliding disk208is compressed.

Accordingly, the forward/reverse rotation of the push rod116on the same axle with the rotating shaft120of the electric motor114is restricted, so that the braking operation of the motor driven brake system during driving can be smoothly performed together with the releasing of the parking brake.

On the other hand, when power to the solenoid204is turned off after the motor driven brake system is operated, the sliding disk208is adhered closely to the friction plate214while being slid by the resilience of the spring210, so that the rotation of the rotating shaft120of the electric motor114is restricted, thereby operating the parking brake.

That is, the locking pin118formed on the rotating shaft120of the electric motor114is stuck in the locking groove212in the horizontal pipe206integrally formed with the sliding disk208in the state in which the sliding disk208is adhered closely to the friction plate214, so that the rotating shaft120of the electric motor114is not rotated, thereby operating the parking brake. Accordingly, the reverse rotation of the push rod116on the same axle with the rotating shaft120of the electric motor114is restricted, so that the braking power of the parking brake is maintained.

However, in the conventional motor driven brake system having the parking brake, the operating noise of the solenoid is increased during operation and releasing of the parking brake. Although the braking power should be released for the purpose of safety when the supply of power to the solenoid is stopped while driving, the braking power cannot be released once a power failure occurs. Therefore, the vehicle may lose control, possibly causing a fatal accident.

In other words, when power is not supplied to the solenoid due to an error or failure in the controller when the motor driven brake system is operated during driving of the vehicle when the parking brake is released, i.e., when the power is applied to the solenoid to be turned on, the parking brake is operated as described above, and therefore, the braking power of the motor driven brake system may not be released. Accordingly, the vehicle may lose control thereby causing an accident.

SUMMARY OF THE DISCLOSURE

The present invention provides a motor driven brake system in which a parking brake is implemented using a compact motor and a plurality of disks and friction pads mutually fractionized or released by the compact motor, so that it is possible to reduce operating noise of a solenoid as compared with that of an existing solenoid and to prevent a phenomenon that although a power failure of the compact motor occurs during driving, the braking power of the motor driven brake system is not released.

In one aspect, the present invention provides a motor driven brake system including an electric motor for providing braking power, a push rod that is a shaft in the outer direction of the electric motor, a rotating shaft that is a shaft in the inner direction of the electric motor, and a parking brake housing mounted within the housing where an electric motor or electric motor with a reduction gear is mounted. More specifically, this system including: sliding disks and friction pads, alternately mounted between the outside diameter of the rotating shaft and the inside diameter of the parking brake housing to restrict or release the rotation of the rotating shaft; a pressure member disposed adjacent to the outermost sliding disk to press the sliding disks and the friction pads, and having a screw aperture formed in an outer surface thereof; a compact motor mounted to an outside inner wall surface of the parking brake housing so as to be operated by receiving power supplied only in the braking of a parking brake and the releasing of the braking of the parking brake; and a screw-shaped push rod, as a driving shaft of the compact motor, inserted into the screw aperture of the pressure member so as to perform a standing rotation for the purposed of the forward-and-backward movement of the pressure member.

In an exemplary embodiment, a guide member guiding a rectilinear movement of the pressure member while surrounding the outside diameter surface of the pressure member may be mounted to the inside diameter surface of the parking brake housing.

In another exemplary embodiment, a fixing disk providing bearing power when the sliding disks and the friction pads are pressed may be mounted between the inner surface of the electric motor and the innermost friction pad.

In still another exemplary embodiment, a first projection may be formed on the inside diameter surface of the parking brake housing, and a first recessed groove having the first projection inserted and fastened thereinto may be formed in the outside diameter surface of the friction pad.

In yet another exemplary embodiment, a second projection may be formed on the inside diameter surface of the sliding disk, and a second recessed groove having the second projection inserted and fastened thereinto may be formed in the outside diameter surface of the rotating shaft.

In still yet another exemplary embodiment, a third projection may be formed on the inside diameter surface of the guide member, and a third recessed groove having the third projection inserted and fastened thereinto may be formed in the outside diameter surface of the pressure member.

Advantageously, since power for the parking brake while driving is not required like in the existing solenoid-type parking brake, it is possible to reduce power consumption and to considerably decrease the operating noise of the solenoid.

Second, the existing solenoid-type parking brake has a disadvantage in that when a power failure of the solenoid occurs when the braking of the motor driven brake system is performed while driving, the vehicle loses control due to the phenomenon that the operating of the parking brake and the braking of the motor driven brake system is not performed because the solenoid does not turn off. However, in the present invention, it is unnecessary to supply power to the parking brake while driving, so that it is possible to prevent the brake from not releasing and to prevent any loss of control of the vehicle.

Third, a multi-stage disk and a friction pad, including a compact motor, are used to prevent the unlocking of a motor for operating the motor driven brake system when the parking brake is operated, so that it is possible to reduce the weight and cost of the entire brake system.

Fourth, although a failure of the parking brake occurs, the braking of the motor driven brake system and the releasing of the braking of the motor driven brake system are possible, thereby improving safety.

DETAILED DESCRIPTION

Additionally, it is understood that the below methods are executed by at least one controller. The term controller refers to a hardware device that includes a memory and a processor. The memory is configured to store the instructions and the processor is specifically configured to execute said instructions to perform one or more processes which are described further below.

FIGS. 3 and 4are sectional views illustrating a motor driven brake system including a parking brake according to an exemplary embodiment of the present invention. InFIGS. 3 and 4, reference numeral100represents a motor driven brake system, and reference numeral200represents a parking brake.

The motor driven brake system100basically includes friction pads104attached in a caliper housing102, and a disk106disposed between the friction pads104so as to be pressed by the friction pads104when the brakes are applied.

A piston108movable forward and backward is installed in a horizontal through aperture of a caliper housing102, and a pressure member110having a screw aperture is integrally installed inside the piston108.

In this case, a reduction gear and an electric motor114having both side shafts are mounted at an inner end portion of the caliper housing102. Here, an outside shaft of the electric motor114is connected by means of the reduction gear to a screw-shaped push rod116inserted and fastened into the screw aperture112of the pressure member110, and an inside shaft on the same axle with the outside shaft is employed as a rotating shaft120.

Meanwhile, as one configuration of the parking brake200, a parking brake housing202is integrally mounted to an inner surface of the electric motor114, and the rotating shaft120of the electric motor114is rotatably disposed at a central portion of the parking brake housing202.

Here, a plurality of sliding disks302and a plurality of friction pads304are alternately stacked and arranged between the outside diameter of the rotating shaft120and the inside diameter of the parking brake housing202. Here, the sliding disks302and the friction pads304restrict the rotation of the rotating shaft120to perform the braking of the parking brake or release the restriction of the rotation of the rotating shaft to release the braking of the parking brake. In this case, a fixing disk316is mounted between the inner surface of the electric motor114and the innermost friction pad304. Here, the fixing disk316serves as a support plate when the sliding disks302and the friction pads304are pressed.

A pressure member308moving forward and backward as a means for pressing the sliding disks302and friction pads304is disposed adjacent to the outermost sliding disk. Thus, a screw aperture306for connecting the pressure member308to a compact motor310is formed in the outer surface of the pressure member308.

Particularly, the compact motor310as a driving source allowing the pressure member308to move forward and backward so as to press the sliding disks302and the friction pads304is mounted to the outside inner wall surface. Thus, the compact motor310is maintained in a power-off state at normal times, and is driven by receiving power supplied only in the braking and releasing of the parking brake.

To this end, a screw-shaped push rod312that is a driving shaft of the compact motor310is inserted and fastened into the screw aperture306of the pressure member308so as to perform a standing rotation. The push rod312allows the pressure member308to move forward and backward.

A guide member314is mounted to the inside diameter surface of the parking brake housing202. The guide member314guides the rectilinear movement of the pressure member308while surrounding the outside diameter surface of a horizontal pipe of the pressure member308.

In order to restrict the rotation of the friction pad304, as shown inFIG. 5, a first projection318is formed on the inside diameter surface of the parking brake hosing202, and a first recessed groove320is formed in the outside diameter surface of the friction pad304.

Thus, the first projection318is inserted and fastened into the first recessed groove320, so that the friction pad304is fixed to the inside diameter surface of the parking brake housing202, and simultaneously, the inside diameter surface of the friction pad304is spaced apart from the rotating shaft120.

In order to rotate the sliding disk302together with the rotating shaft120, as shown inFIG. 6, a second projection322is formed on the inside diameter surface of the sliding disk302, and a second recessed groove324is formed in the outside diameter surface of the rotating shaft120.

Thus, the second projection322is inserted and fastened into the second recessed groove324, so that the sliding disk302is fixed to the outside diameter surface of the rotating shaft120, and simultaneously, the outside diameter surface of the sliding disk302is spaced apart from the inside diameter surface of the parking brake housing202.

In order to ensure the rectilinear movement of the pressure member308, as shown inFIG. 7, a third projection326is formed on the inside diameter surface of the guide member314, and a third recessed groove328having the third projection326inserted and fastened thereinto is formed in the outside diameter surface of the pressure member308. Thus, when the pressure member308performs a forward-and-backward rectilinear movement, the third projection326of the guide member314is inserted into the third recessed groove328, thereby guiding the rectilinear movement of the pressure member308. Accordingly, it is possible to ensure the forward-and-backward rectilinear movement of the pressure member308.

Hereinafter, the operation of the motor driven brake system configured as described above will be described as follows.

Operation (Braking) of Parking Brake

FIG. 3is a section view illustrating an operating state of the parking brake of the motor driven brake system according to the embodiment of the present invention.FIG. 8is a flowchart illustrating an operation of the motor driven brake system.

When the push rod116of the electric motor114performs a standing rotation in the forward direction by applying power from the controller220to the electric motor114of the motor driven brake system100, the pressure member110fastened to the push rod116performs a rectilinear movement toward a vehicle outer direction. This is because the push rod116is formed in a screw shape.

Continuously, the piston108integrally formed with the pressure member110presses the friction pads104, and simultaneously, the disk106interposed between the friction pads104is pressed, so that braking of the vehicle is performed.

When the clamping force of the friction pad104with respect to the disk106is greater than a reference value A or when the rotational angle of the electric motor114is greater than a reference value B, the controller220applies power to the compact motor310. Accordingly, when the push rod312of the compact motor310performs a standing rotation in the forward direction, the pressure member308fastened to the push rod312moves forward. This is because the push rod312is also formed in the screw shape.

Continuously, as the pressure member308moves forward, the sliding disk302and the friction pad304are adhered closely to each other, so that the rotating shaft120of the electric motor114is restricted so as not to be rotated any more.

When the current applied from the controller220to the compact motor310is greater than a reference value C or when the rotational angle of the compact motor310is greater than a reference value D, the supply of power to the electric motor114and the compact motor310is stopped. Thus, the rotating shaft120of the electric motor114is restricted, and simultaneously, the reverse rotation of the push rod116on the same axle with the rotating shaft120is restricted, thereby performing the operation (braking) of the parking brake.

Releasing of Operation (Braking) of Parking Brake

FIG. 4is a sectional view illustrating a released state of the parking brake of the motor driven brake system according to the embodiment of the present invention.FIG. 9is a flowchart illustrating an operation of the motor driven brake system. First, when the push rod116of the electric motor114performs a standing rotation in the reverse direction by applying power from the controller220to the electric motor114of the motor driven brake system, the pressure member110fastened to the push rod116performs a rectilinear movement toward a vehicle inner direction. This is because the push rod116is formed in the screw shape.

Simultaneously, when the push rod312of the compact motor310performs a standing rotation in the reverse direction by applying power from the controller220to the compact motor310, the pressure member308fastened to the push rod312moves backward. This is because the push rod312is also formed in the screw shape.

Continuously, as the pressure member308moves backward, the state in which the sliding disk302and the friction pad304are adhered closely to each other is released, so that the rotating shaft120of the electric motor114becomes a rotatable state. Thus, the cylinder108integrally formed with the pressure member110of the motor driven brake system100moves backward, and the clamping force of the disk106due to the friction pad104is released, so that the braking of the parking brake is released.

Finally, when the current applied from the controller220to the compact motor310is greater than a reference value E or when the rotational angle of the compact motor310is less than a reference value F, the supply of power to the compact motor310is stopped.

Meanwhile, since the restriction of the rotating shaft120of the electric motor114is released during driving of the vehicle, the controller220controls the driving of the electric motor114according to the input of a brake pedal, so that the braking of the motor driven brake system can be smoothly performed. Further, since it is unnecessary to supply power to the compact motor of the parking brake while driving, the braking of the motor driven brake system is not released, so that it is possible to easily prevent the occurrence of a spin of the vehicle.