Claims:

1. A parking brake system (118), comprising:
a parking brake switch (128) that operates in one of an activated state and a deactivated state;
a gearbox (106) housing a plurality of gears (104);
a locking gear (120) disposed in one of a locked position (122) and an unlocked position (124) with respect to one or more of the gears (104) when the parking brake switch (128) is in the activated state and the deactivated state, respectively, wherein the locking gear (120) is physically engaged with one or more of the gears (104) when disposed in the locked position (122) to prevent rotation of the gears (104), and wherein the locking gear is disposed in a physically offset position (123) from one or more of the gears (104) when disposed in the unlocked position (124) to allow rotation of the gears (104);
an actuator unit (126) coupled to the locking gear (120) and the parking brake switch (128), wherein the actuator unit (126) linearly moves the locking gear (120) from the physically offset position (123) to the locked position (122) upon activation of the parking brake switch (128), and wherein the actuator unit (126) disengages the locking gear (120) from the gears (104) and moves the locking gear (120) from the locked position (122) to the physically offset position (123), thereby disposing the locking gear (122) in the unlocked position (124).

2. The parking brake system (118) as claimed in claim 1, wherein the gearbox (106) is a planetary gearbox (106) and the plurality of gears (104) comprise a sun gear (104a) and one or more planetary gears (104b), wherein the locking gear (120) is physically engaged with either the sun gear (104a) or one or more of the planetary gears (104b) when disposed in the locked position (122).

3. The parking brake system (118) as claimed in claim 2, wherein the actuator unit (126) comprises:
a cylinder (130);
a piston (132) disposed within the cylinder (130);
a gear mount flange (134) coupled to a proximal end of the piston (132), wherein the locking gear (120) is coupled to the piston (132) via the gear mount flange (134); and
a driving unit (137) that is operatively coupled to the piston (132) and linearly moves the piston (132) between a first position (132a) and a second position (132b) within the cylinder (130), wherein the linear movement of the piston (132) to the second position (132b) positions the locking gear (120) either between the sun gear (104a) and one or more of the planetary gears (104b), or between two or more of the planetary gears (104b), and a linear movement of the piston (132) to the first position (132b) retracts the locking gear (120) to the physically offset position (123).

4. The parking brake system (118) as claimed in claim 3, wherein the driving unit (137) comprises one or more of a hydraulic system, a pneumatic system, an electric motor, linear variable differential transformer, and a solenoid switch.

5. The parking brake system (118) as claimed in claim 3, wherein the actuator unit (126) comprises a flexible member (136) disposed between the gear mount flange (134) and the locking gear (120), wherein the flexible member (136) comprises one of a helical spring and a coil spring.

6. The parking brake system (118) as claimed in claim 3, wherein the parking brake system (118) comprises:
a position identification unit (135) comprising one or more sensors (138, 140, 1001) and operatively coupled to the gearbox (106), wherein the sensors (138, 140, 1001) provide one or more measurements indicative of one or more of a position and orientation of the gears (204);
a parking brake control subsystem (142) operatively coupled to the position identification unit (135), wherein the parking brake control subsystem (142):
identifies one or more of a position and orientation of the gears (104) based on the sensor measurements;
identifies the gears (104) to be rotating when one or more of the identified position and orientation changes over a designated period of time and identifies the gears (104) to be stationary when the identified position and orientation remain the same over the designated period of time;
determines and stores one or more of a degree of rotation required to reposition the gears (104) from different initial positions and orientations to a plurality of new positions and orientations during an initial configuration process as stored correlations;
an electric motor (102) operatively coupled to the parking brake control subsystem (142) and adapted to rotate the gears (104) by the determined degree of rotation to reposition the gears (104) to a new position to engage with the locking gear (120) when the parking brake control subsystem (142) identifies the gears (104) to be stationary.

7. The parking brake system (118) as claimed in claim 6, wherein the position identification unit (135) comprises:
one or more infrared reflectors (140) mounted on one or more of the sun gear (104a) and the planetary gears (104b) in a regularly spaced radial pattern;
an infrared sensor (138) disposed on the gearbox (106) and adapted to transmit infrared rays towards the infrared reflectors (140) that reflect the infrared rays to generate different reflection patterns for different positions and orientations of the of the gears (104);
wherein the parking brake control subsystem (142) identifies and stores correlations between a plurality of reflection patterns and a corresponding plurality of different initial positions and orientations of the gears (104) that result in generation of the reflection patterns during the initial configuration;
wherein the parking brake control subsystem (142) identifies one or more of a position and orientation of the gears (104) by comparing the reflection patterns generated by the infrared reflectors (14) with the stored correlations;
wherein the parking brake control subsystem (142) identifies the gears (104) to be rotating when the reflection patterns change over a designated period of time and identifies the gears (104) to be stationary when the reflection patterns remain the same over the designated period of time; and
wherein the parking brake control subsystem (142) controls the electric motor (102) to rotate the gears (104) by the determined degree of rotation to reposition the gears (104) to a new position to engage with the locking gear (120) when the parking brake control subsystem (142) identifies the gears (104) to be stationary.

8. The parking brake system (118) as claimed in claim 6, wherein the position identification unit (135) comprises a Hall-effect sensor (1001) disposed on the planetary gears (104b), wherein an output voltage of the Hall-effect sensor (1001) increases when the planetary gears (104b) approach the Hall-effect sensor (1001) and decreases when the planetary gears (104b) move away from the Hall-effect sensor (1001);
wherein the parking brake control subsystem (142) identifies and stores correlations between a plurality of output voltages and a corresponding plurality of different initial positions and orientations of the gears (104) during the initial configuration;
wherein the parking brake control subsystem (142) identifies one or more of a position and orientation of the gears (104) by comparing the output voltage with the stored correlations;
wherein the parking brake control subsystem (142) identifies the gears (104) to be rotating when the output voltage changes over a designated period of time and identifies the gears (104) to be stationary when the output voltage remains the same over the designated period of time; and
wherein the parking brake control subsystem (142) controls the electric motor (102) to rotate the gears (104) by the determined degree of rotation to reposition the gears (104) to a new position to engage with the locking gear (120) when the parking brake control subsystem (142) identifies the gears (104) to be stationary.

9. The parking brake system (118) as claimed in claim 3, wherein the locking gear (120) comprises one or more slots (801) through which one or more fasteners (802) run through to couple the locking gear (120) to the gear mount flange (134), wherein the locking gear (120) is adapted to swivel in the slots (801) about an associated central axis (803) when moving from the unlocked position (124) to the locked position (122) to engage with the planetary gears (104) and from the locked position (122) to the unlocked position (124) to disengage from the planetary gears (104), wherein the fasteners (802) comprise one or more of a nut and bolt arrangement, a screw, a rivet, and a snap-fit joint.

10. The parking brake system (118) as claimed in claim 1, wherein the parking brake system (118) is a subsystem deployed in one of a vehicle (100), a power generation turbine, a windmill, a compressor, an aero engine, and an industrial system comprising one or more rotatable gears and a braking mechanism.

, Description:

RELATED ART

[0001] Embodiments of the present specification relate generally to a parking brake of a vehicle. More particularly, the present specification relates to a parking brake for use in an electric vehicle or a vehicle with a single speed transmission.
[0002] Conventional vehicles include service brakes to decelerate or completely stop the vehicle as and when needed. While service brakes may be sufficient to keep the vehicle immobile on a flat surface, these may not be as effective in resisting the pull of gravity when the vehicle is parked on a slope, especially when the engine is switched off. Therefore, most vehicles include a parking brake that prevents movement of the vehicle when it is parked on a slope or an inclined plane. In certain cases, the parking brake also acts as an emergency braking system. Typical parking brakes include a parking brake lever and a cable attached to brake shoes positioned near the wheels of the vehicle. When the brake lever is pulled, the brake shoes engage with an associated wheel disc to stop the rotation of the wheels. In electric vehicles or vehicles with single speed transmission, an actuating button or a key may function as the brake lever. When the button is pressed, the parking brake is engaged to prevent the rotation of vehicle’s wheels by stalling the rotation of the gears in a gearbox.
[0003] Conventional parking brake systems typically employ a rack and pinion arrangement or a mechanism with a locking gear and a parking pawl. For example, US patent publication US20190162304A1 describes a parking brake mechanism including a parking gear, a parking pawl, a cam, a parking rod, and a spring. When the parking brake is engaged, the parking rod moves in the forward direction, and the cam is biased towards the parking pawl by the spring. The parking pawl has a single engaging tooth at the front end that locks with external teeth of the parking gear for preventing rotation of the parking gear.
[0004] However, the spring and single engaging tooth mechanisms are prone to fail under intense load and/or fatigue acting on the parking brake due to the elevation of the vehicle parked on a steep inclined plane. Similarly, other conventional rack and pinion arrangements are also prone to slippage under stress, leading to failure of an associated parking brake mechanism. Such a parking brake failure may lead to unexpected disengagement of the parking brake, which in turn, may cause a vehicle to skid off the road, endanger the life of occupants and nearby pedestrians, and even result in destruction of life and property.
[0005] Therefore, there is a need for an improved parking brake system that can withstand higher loads and allows for safer and more reliable parking of the vehicle on different gradient surfaces.

BRIEF DESCRIPTION

[0006] It is an objective of the present disclosure to provide a parking brake system. The parking brake system includes a parking brake switch, a gearbox, a locking gear, and an actuator unit. The parking brake switch operates in one of an activated state and a deactivated state. The gearbox houses a plurality of gears. The locking gear disposed in one of a locked position and an unlocked position with respect to one or more of the gears when the parking brake switch is in the activated state and the deactivated state, respectively. The locking gear is physically engaged with one or more of the gears when disposed in the locked position to prevent rotation of the gears. The locking gear is disposed in a physically offset position from one or more of the gears when disposed in the unlocked position to allow rotation of the gears.
[0007] The actuator unit coupled to the locking gear and the parking brake switch. The actuator unit linearly moves the locking gear from the physically offset position to the locked position in between the gears upon activation of the parking brake switch. The actuator unit disengages the locking gear from the gears and moves the locking gear from the locked position to the physically offset position from the gears, thereby disposing the locking gear in the unlocked position. The gearbox is a planetary gearbox and the plurality of gears includes a sun gear and one or more planetary gears. The locking gear is physically engaged with either the sun gear or one or more of the planetary gears when disposed in the locked position.
[0008] The actuator unit includes a cylinder, a piston disposed within the cylinder, a gear mount flange, and a driving unit. The gear mount flange coupled to a proximal end of the piston. The locking gear is coupled to the piston via the gear mount flange. The driving unit is operatively coupled to the piston and linearly moves the piston between a first position and a second position within the cylinder. The linear movement of the piston to the second position positions the locking gear between the sun gear and one or more planetary gears, or between two or more of the planetary gears. A linear movement of the piston to the first position retracts the locking gear to the physically offset position. The driving unit includes one or more of a hydraulic system, a pneumatic system, an electric motor, linear variable differential transformer, and a solenoid switch.
[0009] The actuator unit includes a flexible member disposed between the gear mount flange and the locking gear. The flexible member includes one of a helical spring or a coil spring. The parking brake system includes a position identification unit, a parking brake control subsystem, and an electric motor. The position identification unit includes one or more sensors and operatively coupled to the gearbox. The sensors provide one or more measurements indicative of one or more of a position and orientation of the gears. The parking brake control subsystem operatively coupled to the position identification unit and identifies one or more of a position and orientation of the gears based on the sensor measurements. Further, the parking brake control subsystem identifies the gears to be rotating when one or more of the identified position and orientation changes over a designated period of time and identifies the gears to be stationary when the identified position and orientation remain the same over the designated period of time.
[0010] Furthermore, the parking brake control subsystem determines and stores one or more of a degree of rotation required to reposition the gears from different initial positions and orientations to a plurality of new positions and orientations during an initial configuration process as stored correlations. The electric motor operatively coupled to the parking brake control subsystem and adapted to rotate the gears by the determined degree of rotation to reposition the gears to a new position to engage with the locking gear when the parking brake control subsystem identifies the gears to be stationary. The position identification unit includes one or more infrared reflectors and an infrared sensor. The infrared reflectors mounted on one or more of the sun gear and the planetary gears in a regularly spaced radial pattern. The infrared sensor disposed on the gearbox and adapted to transmit infrared rays towards the infrared reflectors that reflect the infrared rays to generate different reflection patterns for different positions and orientations of the of the gears.
[0011] The parking brake control subsystem identifies and stores correlations between a plurality of reflection patterns and a corresponding plurality of different initial positions and orientations of the gears that result in generation of the reflection patterns during the initial configuration. The parking brake control subsystem identifies one or more of a position and orientation of the gears by comparing the reflection patterns generated by the infrared reflectors with the stored correlations. The parking brake control subsystem identifies the gears to be rotating when the reflection patterns change over a designated period of time and identifies the gears to be stationary when the reflection patterns remain the same over the designated period of time. The parking brake control subsystem controls the electric motor to rotate the gears by the determined degree of rotation to reposition the gears to a new position to engage with the locking gear when the parking brake control subsystem identifies the gears to be stationary. The position identification unit includes a Hall-effect sensor disposed on the planetary gears. An output voltage of the Hall-effect sensor increases when the planetary gears approach the Hall-effect sensor and decreases when the planetary gears move away from the Hall-effect sensor.
[0012] The parking brake control subsystem identifies and stores correlations between a plurality of output voltages and a corresponding plurality of different initial positions and orientations of the gears during the initial configuration. The parking brake control subsystem identifies one or more of a position and orientation of the gears by comparing the output voltage with the stored correlations. The parking brake control subsystem identifies the gears to be rotating when the output voltage changes over a designated period of time and identifies the gears to be stationary when the output voltage remains the same over the designated period of time. The parking brake control subsystem controls the electric motor to rotate the gears by the determined degree of rotation to reposition the gears to a new position to engage with the locking gear when the parking brake control subsystem identifies the gears to be stationary.
[0013] The locking gear includes one or more slots through which one or more fasteners run through to couple the locking gear to the gear mount flange. The locking gear is adapted to swivel in the slots about an associated central axis when moving from the unlocked position to the locked position to engage with the planetary gears and from the locked position to the unlocked position to disengage from the planetary gears. The fasteners include one or more of a nut and bolt arrangement, a screw, a rivet, and a snap-fit joint. The parking brake system is a subsystem deployed in one of a vehicle, a power generation turbine, a windmill, a compressor, an aero engine, and an industrial system including one or more rotatable gears and a braking mechanism.
DRAWINGS
[0014] These and other features, aspects, and advantages of the claimed subject matter will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
[0015] FIG. 1 illustrates a block diagram depicting exemplary components of a vehicle including a parking brake system, in accordance with aspects of the present disclosure;
[0016] FIG. 2 illustrates a front view of a locking gear when engaged with rotatable gearwheels of a planetary gearbox in the parking brake system of FIG. 1, in accordance with aspects of the present disclosure;
[0017] FIG. 3 illustrates an isometric view of a locking gear engaged with rotatable gearwheels of the planetary gearbox in the parking brake system of FIG. 1, in accordance with aspects of the present disclosure;
[0018] FIGS. 4 -5 illustrate a side view and an isometric view of the parking brake system of FIG. 1, respectively, when the locking gear is engaged with rotatable gearwheels of the planetary gearbox, in accordance with aspects of the present disclosure;
[0019] FIGS. 6-7 illustrate a side view and an isometric view of the parking brake system of FIG. 1, respectively, when the locking gear is disengaged from rotatable gearwheels of the planetary gearbox, in accordance with aspects of the present disclosure; and
[0020] FIGS. 8 and 9 illustrate a front view and a side view of the locking gear of FIG. 1 including a swiveling mechanism for engaging and disengaging with the rotatable gearwheels;
[0021] FIG. 10 illustrates an alternate embodiment of the parking brake system using a Hall-effect sensor, in accordance with aspects of the present disclosure; and
[0022] FIGS. 11-12 illustrate graphical representations of induced voltage in the Hall-effect sensor when the gears are positioned proximal to and away from the Hall-effect sensor, respectively.

DETAILED DESCRIPTION

[0023] The following description presents a novel parking brake assembly. Conventional parking brake systems employ a parking pawl and a locking gear with a spring attachment that are prone to failure under excessive stress, for example, caused when an associated system such as a vehicle is parked on a steep inclined plane. In certain other presently available systems, the parking brake mechanism employs a rack and pinion arrangement, which is unreliable due to slippage between the rack and the pinion. Such failures may result in significant loss of life and property.
[0024] Unlike such conventional systems, the present parking brake assembly employs a robust locking gear adapted to securely engage and disengage with a plurality of rotatable gearwheels housed within a planetary gearbox for reliable parking. Upon activation of the parking button, the present locking gear mechanism engages the locking gear with the plurality of rotatable gearwheels to stall the rotation of the rotatable gearwheels completely. Upon deactivation of the parking button, the locking gear mechanism disengages from the plurality of rotatable gearwheels to allow for rotation of the rotatable gearwheels to restore motion of the vehicle.
[0025] It may be noted that embodiments of the present brake assembly may be used in systems such as vehicles, and other manufacturing and industrial systems with rotatable gearwheels and braking mechanisms. However, for clarity, the present disclosure describes an embodiment of the brake assembly with reference to a manual or a single speed transmission vehicle. In particular, the structure and functioning of the parking brake assembly that allows for reliable parking of the vehicle on different terrains and gradients is described in greater detail with reference to FIGS. 1-12.
[0026] FIG. 1 illustrates a block diagram of a vehicle (100), for example, driven by an electric motor (102). The electric motor (102) causes a plurality of gears (104) housed in a gearbox (106) in the vehicle (100) to move by actuating a shaft (108) connected between the electric motor (102) and the plurality of gears (104). The plurality of gears (104) includes a sun gear (104a) and one or more planetary gears (104b). For example, the embodiments depicted in FIGS. 2-3 show the plurality of planetary gears (104b) positioned surrounding the sun gear (104a). The planetary gears (104b) are further connected to a carrier wheel (104c) that enables the planetary gears (104b) to rotate around the sun gear (104a) while maintaining their engagement with the sun gear (104a). The rotation of the sun gear (104a) engaged with the planetary gears (104b) causes rotation of an associated driveshaft (112) connected to a differential (110) in the vehicle (100). The differential (110), in turn, transfers the resulting motion to one or more wheels (114) of the vehicle (100) through wheel axles (116). Rotation of the sun gear (104a) and the planetary gears (104b), thus, ultimately causes the vehicle (100) to move.
[0027] Occasionally, the vehicle (100) may also start moving when positioned on an inclined surface due to gravitational forces acting on the vehicle. Therefore, when parking on inclined surfaces, the driver of the vehicle (100) employs a parking brake system (118) located at a lower side of the gearbox (106). The parking brake system (118) is specially designed to overcome the gravitational pull to keep the vehicle (100) stationary and prevent any undesirable movement of the vehicle (100). In particular, the parking brake system (118) prevents rotation of the sun gear (104a) and the planetary gears (104b) to ensure that the vehicle (100) cannot move once it is parked.
[0028] Furthermore, unlike conventional braking systems that employ a spring or rack and pinion arrangements that are prone to failure, the parking brake system (118) includes a locking gear (120) that reliably moves between a locked position (122) and an unlocked position (124) with respect to the gearbox (106). According to aspects of the present disclosure, the locking gear (120) is an additional gear housed within the gearbox (106) and is configured to engage with the gears (104) of the gearbox (106) when the parking brake switch (128) is engaged. To that end, in one embodiment, the locking gear (120) is positioned in between and engages with two consecutive planetary gears (104b) when the parking brake switch (128) is engaged.
[0029] FIG. 2, for example, depicts an exemplary configuration of the locking gear (120) when engaged with the planetary gears (104b) of the planetary gearbox (106) in the parking brake system (118) of FIG. 1. Further, FIG. 3 depicts an alternative isometric view of the exemplary configuration of the locking gear (120) when engaged with the planetary gears (104) of the planetary gearbox (106). Although FIGS. 2-3 depict the locking gear (120) positioned in between and engaged with two of the planetary gears (104b), in an alternative embodiment, the locking gear (120) may be positioned next to and may be engaged with the sun gear (104a) to stall rotation of the planetary gearbox (106) when the parking brake switch (128) is engaged.
[0030] With returning reference to FIG. 1, in certain embodiments, the parking brake system (118) includes an actuator unit (126) coupled to the locking gear (120) to move the locking gear (120) between the locked position (122) and the unlocked position (124). In one embodiment, the actuator unit (126) is activated and deactivated based on an operational state of a parking brake switch or lever (128) in the vehicle (100). In particular, activation of the parking brake switch (128) causes the actuator unit (126) to position and engage the locking gear (120) between the planetary gears (104b) to dispose the gears (104) in the locked position (122). Conversely, deactivation of the parking brake switch (128) causes the actuator unit (126) to physically offset, for example by disengaging and retracting, the locking gear (120) from the locked position (122) between the planet gears (104b) to the unlocked position (124) for allowing the gears (104) in the gearbox (106) to rotate.
[0031] To that end, the actuator unit (126), for example, includes a cylinder (130), a piston (132), a gear mount flange (134) a flexible member (136), and a driving unit (137) operationally coupled with the parking brake switch (128) and the locking gear (120). In one embodiment, the locking gear (120) is coupled to the piston (132) in the actuator unit (126) via the gear mount flange (134). As used herein, the term “gear mount flange” (134) refers to a support element that is positioned at a proximal end (132a) of the piston (132) and couples the locking gear (120) to the piston (132). The gear mount flange (134) and the locking gear (120) are connected by the flexible member (136), which enables minor positional adjustments of the locking gear (120) for smooth engagement/meshing and disengagement/un-meshing of the teeth of the locking gear (120) with the teeth of the gears (104) of the gearbox (106). As used herein, the term “flexible member” refers to a helical or a coil spring that converts spring tension into minor rotational motion of the locking gear (120), for example of up to 90 degrees, for smooth engagement and disengagement of the teeth of the locking gear (120) with the teeth of the gears (104) of the gearbox (106).
[0032] In one embodiment, the flexible member (136) allows the locking gear (120) to rotate only by a maximum of designated degree for smooth engagement of teeth associated with the gears (104), and the locking gear (120). Specifically, the flexible member (136) absorbs the impact of the locking gear (120) engaging with the gears (104) and enables proper positioning of the locking gear (120) with respect to the gears (104) of the planetary gearbox (106). The flexible member (136) also facilitates minor rotational adjustments of the locking gear (120) when attempting to mesh with the gears (104) of the planetary gearbox (106) to ensure that the locking gear (120) meshes perfectly with the teeth of the gears (104) without any slippage in the locked state (122). Conversely, when the parking brake is disengaged, the flexible member (136) facilitates smooth disengagement of the locking gear (120) with the rotatable gearwheels (104) by recoiling to its original position in the unlocked state (124).
[0033] In order to prevent any obstructions and ensure proper and smooth engagement of the locking gear (120) with the gears (104), the position of the gears (104) also needs to be identified accurately. In particular, relative positioning of the teeth of the gears (104) with respect to the teeth of the locking gear (120) needs to be identified for determining the necessary rotation required to smoothly engage and disengage the locking gear (120) from the gears (104). To that end, in one embodiment, the parking brake system (118) includes a position identification unit (135) that is operatively coupled to the gearbox (106). In one embodiment, the position identification unit (135) includes an infrared sensor (138) positioned on the gearbox (106), and a plurality of infrared reflectors (140) mounted on the gears (104) of the gearbox (106). The infrared sensor (138) may include a transmitter for transmitting infrared rays, and a receiver for receiving the infrared rays reflected back from the infrared reflectors (140). In one embodiment, the infrared sensor (138) corresponds to an optocoupler that uses an infrared light emitting diode (LED) as a transmitter and an infrared photodiode or a phototransistor as a receiver.
[0034] In certain embodiments, the plurality of infrared reflectors (140) is located on the sun gear (104a). In an alternative embodiment, however, the plurality of infrared reflectors (140) is located on the teeth of the planetary gears (104b). It may be noted that various sections of the sun gear (104a) and/or the planetary gears (104b) where the infrared reflectors (140) are mounted are referred to herein as “reflection zones,” while the remaining areas are referred to herein as “non-reflection zones.”
[0035] In an exemplary implementation, the infrared reflectors (140) are mounted in a regularly spaced radial pattern on the sun gear (104a). For example, the infrared reflectors (140) may be mounted in a circular pattern on the sun gear (104a) with 90 degrees of difference between any two infrared reflectors (140). In such a configuration, the infrared light beams emitted by the infrared transmitter in the infrared sensor (138) are incident on the sun gear (104a) and are reflected back from the reflection zones, but not from the non-reflection zones. The reflected infrared light beams generate a modulated reflection pattern that is sensed by the infrared receiver in the infrared sensor (138) and is communicated to a parking brake control subsystem (142), for example, as a corresponding pattern of voltage peaks and troughs.
[0036] As used herein, the term “parking brake control subsystem” (142) refers to a microcontroller or processing circuitry, for example, resident in the vehicle (100). The parking brake control subsystem (142) receives signals from the infrared sensor (138) and other sensors and instructs the electric motor (102) to rotate the gears (104) to a desired position to engage with the locking gear (120) without any obstruction or collision. To that end, the parking brake control subsystem (142) identifies a position and/or orientation of the gears (104) based on the received pattern of the infrared beams from the infrared sensor (138). Once a current position and/or orientation of the gears (104) is identified, the parking brake control subsystem (142) determines a degree of rotation required to rotate the gears (104) and transmits corresponding control signals to the electric motor (102). Consequently, the electric motor (102) rotates the gears (104) by the required degree for deploying the gears (104) in the desired position and/or orientation suitable for engaging the gears (104) smoothly with the locking gear (120) when the parking brake is engaged.
[0037] FIGS. 4-5 illustrate a side view and a front perspective view of the parking brake system (118) of FIG. 1 respectively, when the locking gear (120) is engaged in the locked position (122) with the gears (104) of the planetary gearbox (106). In one embodiment, activation of the parking brake switch (128) causes the parking brake control subsystem (142) to identify a current position of the locking gear (120) with respect to the gears (104) based on the received pattern of the infrared beams from the infrared sensor (138). The parking brake control subsystem (142) further determines the required degree of linear and rotational motion needed to move the locking gear (120) in the locked position (122) with the gears (104), for example, using stored correlations identified during an initial configuration of the parking brake system (118). Subsequently, the parking brake control subsystem (142) actuates the driving unit (137) to linearly move the piston (132) between a first position (132a) and a second position (132b) within the cylinder (130). To that end, the driving unit (137), for example, includes one or more of a linear variable differential transformer based driving system, a solenoid switch based driving system, a hydraulic driving system, a pneumatic driving system, and a spring based driving system.
[0038] In one embodiment, the driving unit (137) linearly moves and holds the piston (132) at the first position (132a) in which the locking gear (120) remains at a physically offset position (123) from the gears (104) in the unlocked position (124) when the parking brake switch (128) is in a deactivated state. Alternatively, the driving unit (137) linearly moves and holds the piston (132) at the second position (132b) in which the locking gear (120) remains coupled to the gears (104) in the locked position (122) when the parking brake switch (128) is in an activated state.
[0039] The linear movement of the piston (132) from the first position (132a) to the second position (132b) causes the locking gear (120) to correspondingly move from the unlocked position (124) to the locked position (122). The locking gear (120), thus positioned in the locked position (122) between the planetary gears (104b), prevents rotation of the sun gear (104a) and/or the planetary gears (104b). As the gears (104) stop rotating, the transmission of motion from the gears (104) to the driveshaft (112), and in turn, to the wheels (114) ceases, causing the vehicle (100) to come to a rest and become stationary. The vehicle (100) reverts to a moveable state from a stationary state when the locking gear (120) moves back from the locked position (122) to the unlocked position (124), as described subsequently with reference to FIGS. 6 and 7.
[0040] FIGS. 6-7 depict a side view and a front perspective view of the parking brake system (118) of FIG. 1, respectively, when the locking gear (120) is positioned in the unlocked position (124) with respect to the gears (104) of the planetary gearbox (106). In one embodiment, deactivation of the parking brake switch (128) causes the parking brake control subsystem (142) to actuate the driving unit (137), which retracts and linearly moves the piston (132) back to the first position (132a). The linear movement of the piston (132) to the first position (132a) causes the locking gear (120) to disengage from the planetary gears (104b) and be disposed in the unlocked position (124). The locking gear (120), thus disposed in the unlocked position (124), no longer obstructs the rotation of the sun gear (104a) and the planetary gears (104b). Rotations of the sun gear (104a) and the planetary gears (104b) allows the transmission of motion from the gears (104) to the driveshaft (112), and subsequently from the driveshaft (112) to the wheels (114), causing the vehicle (100) to move.
[0041] In certain embodiments, the parking brake system (118) moves the locking gear (120) from the unlocked position (124) to the locked position (122) only when the gears (104) are stationary. The parking brake system (118) includes this safety feature as moving the locking gear (120) to the locked position (122) while the gears (104) are rotating at a high speed may cause the vehicle (100) to stop abruptly, which may cause the vehicle (100) to skid off the road and topple. Accordingly, in these embodiments, the parking brake system (118) uses a sensor, for example, the infrared sensor (138) or a Hall-effect sensor (See 1001 of FIG. 10) to monitor a change in position of the gears (104) that is indicative of rotary motion.
[0042] For example, when the infrared sensor (138) detects no change in the reflection patterns from the reflection zones, the parking brake system (118) identifies that the gears (104) are stationary. Alternatively, the parking brake system (118) identifies that the gears (104) are in motion when the infrared sensor (138) detects continually changing reflection patterns. Accordingly, the parking brake system (118) holds the piston (132) at the first position (132a) such that the locking gear (120) remains at the physically offset position (123) from the gears (104). Specifically, the locking gear (120) is held in the unlocked position (124) until rotations of the gears (104) stop to prevent any unexpected or undesirable engagement of the locking gear (120) with the gears (104). Only upon actuation of the parking brake switch (128), the parking brake system (118) repositions the piston (132) to the second position (132b) to move the locking gear (120) from the unlocked position (124) to the locked position (122).
[0043] As previously noted, linear movement of the locking gear (120) may cause a collision between the teeth of the locking gear (120) and the teeth of the planetary gears (104b), thus preventing the locking gear (120) from smoothly engaging with the planetary gears (104b). In order to prevent such collisions, the parking brake control subsystem (142) compares the modulated reflection pattern generated by the infrared sensor (138) and the infrared reflectors (140) with stored correlations for identifying and adjusting the position and orientation of the planetary gears (104b) prior to moving the locking gear (120) to the locked position (122).
[0044] To that end, in one embodiment, the parking brake system (118) undergoes an initial configuration process to identify the correlations between different patterns of the reflected infrared beams with corresponding positions and orientations of the gears (104). Such correlations are identified and stored in a storage unit such as a memory device (not shown) associated with the parking brake control subsystem (142). Additionally, the parking brake control subsystem (142) also identifies and stores the degree of rotation needed by the gears (104) to engage and/or disengage with the locking gear (120) when in each of the identified positions and orientations. Subsequently, the parking brake control subsystem (142) may determine the current position and orientation of the gears (104) and the required rotation of gears (104) based on the identified reflection pattern and the corresponding stored correlations.
[0045] The parking brake control subsystem (142) then transmits electrical signals to the electric motor (102) to rotate the planetary gears (104) by the identified degree of rotation for deploying the planetary gears (104b) to a new position and/or orientation. The planetary gears (104b), thus deployed in the new position and orientation, smoothly engage with the locking gear (120) when the locking gear (120) is linearly moved to the locked position (122) by the activation of the parking brake switch (128). In certain embodiments, the smooth engagement between the locking gear (120) and the planetary gears (104b) is further facilitated by a swiveling mechanism present in the locking gear (120), as described subsequently with reference to FIGS. 8 and 9.
[0046] FIGS. 8 and 9 depict a front view and a corresponding side view of the locking gear (120) of FIG. 1 including a swiveling mechanism for smoothly engaging and disengaging with the planetary gears (104b). In one embodiment, the swiveling mechanism includes one or more slots (801) in the locking gear (120). The swiveling mechanism further includes one or more fasteners (802) that run through the slots (801) to attach the locking gear (120) to the gear mount flange (134). Examples of the fasteners (802) include a nut and bolt arrangement, screws, rivets, and snap-fit joints.
[0047] In certain embodiments, during engagement and disengagement of the locking gear (120) with the planetary gears (104b), the slots (801) and the fasteners (802) enable the locking gear (120) to slightly swivel about an associated central axis (803) such that that the locking gear (120) smoothly engages or disengages with the planetary gears (104). For example, during engagement of the locking gear (120) with the planetary gears (104), the locking gear (120) slightly swivels towards right of the central axis (803) until the fasteners (802) engage with left edges (804) of the slots (801). In another example, the locking gear (120) swivels towards left of the central axis (803) until the fasteners (802) engage with right edges (805) of the slots (801). These swiveling movements of the locking gear (120) toward right and left of the central axis (803) allow the locking gear (120) to self-adjust its position and smoothly engage with the planetary gears (104b).
[0048] Although the previously noted embodiments of the parking brake system (118) use the infrared sensor (138) for identifying position, orientation and/or rotational status of the gears (104), in an alternative embodiment, the parking brake system (118) may use other types of sensors. An exemplary embodiment of the parking brake system (118) employing a Hall-effect sensor for determining the position of the gears (104) to ensure smooth engagement and disengagement of the locking gear (120) with the gears (104) is described in greater detail with reference to FIGS. 10-12.
[0049] FIG. 10 illustrates a block diagram of a vehicle (1000) similar to the vehicle (100) depicted in FIG. 1. In particular, the vehicle (1000) includes a parking brake system (118) and other associated components, as shown in FIG. 1. However, the embodiment of the vehicle (1000) depicted in FIG. 10 uses a Hall-effect sensor (1001) in lieu of the infrared sensor (138) and the infrared reflectors (140) of FIG. 1 for determining the position of the gears (104) and/or the locking gear (120).
[0050] To that end, in one embodiment, the hall-effect sensor (1001) is mounted on the planetary gearbox (106) and is in electrical communication with the parking brake control subsystem (142). In one embodiment, the Hall-effect sensor (1001) generates a first voltage due to disruption of an associated magnetic field when the teeth portions of the planetary gears (104) approach the Hall-effect sensor (1001). As the teeth move away from the Hall Effect sensor (1001) the induced voltage recedes. Continuous rotation of the gears (104) leads to continuous disruption in the magnetic field around the Hall Effect sensor (1001) leading to the alternate rise and fall of induced voltage represented by the square wave as shown in FIGS.11-12.
[0051] For example, FIG. 11 illustrates a graphical representation (1101) of a square wave representative of voltage induced in the Hall-effect sensor (1001) due to the movement of the first planetary gear (104b). In the graphical representation (1101), the crest portions (1102) correspond to the voltage induced in the Hall-effect sensor (1001) when the teeth portions of the planetary gear (104b) approach the Hall-effect sensor (1001). Further, the trough portions (1103) correspond to the decrease in voltage when the teeth portions move away from the Hall-effect sensor (1001). Thus, the graphical representation (1101) of square waves with alternate crest and trough portions (1102 and 1103) is indicative of continuing rotational motion of the planetary gear (104b), whereas an extended trough portion (1104) indicates that rotation of the planetary gear (104b) has ceased. The extended trough portion (1104) also indicates that the teeth of the first planetary gear (104b) are oriented away from the Hall-effect sensor (1001). In one embodiment, the Hall-effect sensor (1001) is positioned on the planetary gearbox (106) to provide an optimal space that allows the first planetary gear (104b) to smoothly engage with the locking gear (120) without any obstructions when the teeth of the first planetary gear (104b) are positioned away from the Hall-effect sensor (1001).
[0052] Similarly, FIG. 12 illustrates another graphical representation (1201) of a square wave representative of voltage induced in the Hall-effect sensor (1001) due to the movement of the second planetary gear (104b). In the graphical representation (1201), the crest portions (1202) and trough portions (1203) are indicative of a rotation of the second planetary gear (104b). Particularly, the crest portions (1202) and trough portions (1203) are indicative of an increase and decrease in voltage as the teeth portions of the second planetary gear (104b) approach and move away from the Hall-effect sensor (1001), respectively. Similarly, an extended crest portion (1204) is indicative of the second planetary gear (104b) being stationary with the teeth of the second planetary gear (104b) positioned close to the Hall-effect sensor (1001). In one embodiment, the teeth positioned close to the Hall-effect sensor (1001) may prove to be an obstruction to the smooth engagement of the locking gear (120) with the second planetary gear (104b).
[0053] Accordingly, the parking brake control subsystem (142) determines a degree of rotation needed (104b) to reposition the second planetary gear to a new position and orientation at which the teeth of the second planetary gear (104b) are not in the way of the locking gear (120). As previously noted, the parking brake control subsystem (142) determines the degree of rotation needed by the second planetary gear (104b) based on the correlations generated and stored during the initial configuration of the parking brake system (118). The parking brake control subsystem (142) then transmits electrical signals to the electric motor (102) to rotate the second planetary gear (104b) by the determined degree of rotation for deploying the second planetary gear (104b) to the new position and orientation. The second planetary gear (104b), thus deployed to the new position and orientation, allows the locking gear (120) to move into the locked position (122) by smoothly engaging between the first planetary gear (104b) and the second planetary gear (104b).
[0054] It may be noted that use of the infrared sensor (138) and the Hall-effect sensor (1001) in the embodiments described herein is only exemplary. In certain other embodiments, other suitable devices such as one or more rotational variable differential transformers (RVDT), encoders, optical sensors and other similar sensors may be used to determine the position and orientation of the gears (104a and 104b).
[0055] Embodiments presented herein describe the parking brake system (118) that provides safe parking of the vehicle (100) even on steep inclined planes. Particularly, use of the locking gear (120) in the parking brake system (118) provides greater protection against slippage or breaking due to excessive gravitational pull as compared to conventional spring or rack and pinion arrangements. Thus, the present parking brake system (118) employing the locking gear (120) provides reliable and safe parking of the vehicle (100) on different gradient surfaces, while preventing instances of accidental skidding and movement of the vehicle (100) that may result in destruction of life and property. Furthermore, it may be noted that the description of the present parking brake system (118) with reference to automobiles is only exemplary. In alternative embodiments, the present parking brake system (118) may also find use in systems such as power generation turbines, windmills, compressors, and aero engines.
[0056] Although specific features of various embodiments of the present systems and methods may be shown in and/or described with respect to some drawings and not in others, this is for convenience only. It is to be understood that the described features, structures, and/or characteristics may be combined and/or used interchangeably in any suitable manner in the various embodiments shown in the different figures.
[0057] While only certain features of the present systems and methods have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the claimed invention.

LIST OF NUMERAL REFERENCES:

100, 1000 Vehicle
102 Electric Motor
104, 104a, 104b Sun, Planetary Gears
104c Carrier Wheel
106 Gearbox
108 Shaft
110 Differential
112 Driveshaft
114, 116 Wheels and Wheel Axles
118 Parking Brake System
120 Locking Gear
122, 123, 124 Locked, Physically Offset, and Unlocked Positions With Respect to Gears
126 Actuator Unit
128 Parking Brake Switch
130 Cylinder
132 Piston
132a, 132b First and Second Positions
134 Gear Mount Flange
135 Position Identification Unit
136 Flexible Member
137 Driving Unit
138, 140 Infrared Sensor and Reflectors
142 Parking Brake Control Subsystem
801, 802 Slots and Fasteners
803 Central Axis
804, 805 Left and Right Edges
1001 Hall-Effect Sensor
1101, 1201 Graphical Representations of Induced and Receding Voltages
1102, 1202 Crest Portions
1103, 1203 Trough Portions
1103, 1203 Trough Portions
1104 Extended Trough Portion
1204 Extended Crest Portion