The Present disclosure in general, relates to a vehicle. Particularly, but not exclusively, the disclosure relates to a throttle actuation device with a friction mechanism and cruise mode cancel mechanism for a vehicle.
BACKGROUND
Generally, the vehicles such as two-wheeled vehicles including motorcycle, mopeds, etc and the three wheeled vehicles an accelerator or throttle grip is provided on a handlebar of the steering mechanism. The throttle grip is operable by a rider or driver to regulate flow of air fuel mixture or in some cases flow of air (by opening and closing a throttle valve) to the internal combustion engine for controlling speed. The throttle grip is usually rotatably mounted on a handlebar of the vehicle, and the throttle grip is rotated by the rider or driver with respect to the handlebar. Conventionally, the throttle grip is connected to the throttle valve through a cable. With advancements in the technology, electronic throttle actuation systems have been developed and it is known in the art to use a position detection device, which detects the rotational movement of the throttle grip utilizing a non-contact angle sensor and the throttle valve is opened and closed by an actuator depending upon an output voltage from the non-contact angle sensor.
Further, it is known in the art to that if the throttle grip is rotated in a counter-clockwise(normal direction) speed of the vehicle will increase. To cancel the cruise mode set by left hand side switch the throttle grip is rotated in clockwise direction an opposite direction to the normal direction.
One such conventional technique is described in US20160194049A1 which discloses a forward and backward speed adjusting handle for an electric vehicle that can be rotated forward and backward so as to control the forward and backward movement of the electric vehicle. However, this arrangement uses a plunger in a guiding portion, this guiding portion which fails to provide a proper pathway for operation/movement of the plunger which may

result in faulty operation of the accelerator. Further, the plunger and a throttle boss are in surface contact which will increase wear of throttle boss and plunger interacting faces and may result in shifting the zero position of throttle over a period.
US10377441B2 describes a throttle grip apparatus that includes a throttle grip, an inter-locking member which comprises engaged parts to be engaged with engaging parts formed on the throttle grip. These engaging parts is rotatable in conjunction with rotation of the throttle grip. Further a first biasing unit biases an interlocking member when the throttle grip rotates in a normal direction. Also, a second biasing unit biases the interlocking member when the throttle grip rotates in a reverse direction. This apparatus further includes a separate rotary member for magnet assembly which is rotated by the interlocking member with gear mechanism thus making the assembly complicated. However, even this apparatus requires special arrangement of sealing to ensure proper operation of gear mechanism which increases costs and complexity of apparatus.
The present disclosure is directed to overcome one or more limitations stated above or any other limitations associated with the prior arts.
SUMMARY OF THE DISCLOSURE
One or more shortcomings of existing apparatus have been overcome, and additional advantages are provided through the apparatus as claimed in the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
In one non limiting embodiment of the disclosure, a throttle actuation device for a vehicle is disclosed. The device includes a throttle grip rotatable from a zero position towards at least one of a normal direction and a reverse direction. The device comprises a rotor rotatably disposed within a housing. The rotor is connectable to the throttle grip and being configured to rotate within the housing based on rotation of the throttle grip. Further, a

torsion spring is provided having a first end attached to the housing and a second end attached to the rotor. The torsion spring is configured to bias the rotor towards the zero position when the throttle grip rotates in at least one of normal and reverse direction. A friction mechanism of the device is disposed within the housing and connected to the rotor. The friction mechanism comprising a friction spring secured to the housing and a friction plunger loaded by the friction spring onto the rotor and oppose rotation of the rotor in the normal direction. The device further includes a magnet disposed on the rotor such that the magnet rotates along with the rotor. Further, a magnetic sensor is disposed within the housing and configured generate a signal corresponding to variation in the magnetic field based on rotation of the throttle grip to adjust A throttle position based on the signal corresponding to variation in the magnetic field.
In an embodiment, a cruise mode cancel mechanism is disposed within a circular guide of the housing and adjacent to the rotor. The cruise mode cancel mechanism comprises a return spring secured at one end with the housing and another end coupled to a return plunger. The return plunger is adapted to contact an extended portion of the rotor at the zero position and to generate a return force when the throttle grip is rotated in reverse direction and provides a cancellation signal to an electronic control unit.
In an embodiment, the housing is defined with a positive stopper adjacent to the friction plunger. The positive stopper is adapted to abut a rotor surface and restrict the rotation of the throttle grip and rotor in the normal direction.
In an embodiment, the housing is defined with a projection extending radially from the throttle grip and is adapted to contact a contact surface of the rotor to actuate the rotor in the reverse direction.
In an embodiment, the projection defined on the throttle grip is adapted to come in contact with a contact surface of the rotor to actuate rotation of the rotor in the normal direction.

In an embodiment, a cover is coupled to the housing to enclose the rotor, the torsion spring, the friction mechanism, the cruise mode cancel mechanism, the magnet and the magnetic sensor within the housing.
In an embodiment, the magnetic sensor is disposed on a printed circuit board operated by a power of the electronic control unit.
In an embodiment, the power is supplied to the electric control unit via a battery of the vehicle.
In an embodiment, the magnetic sensor is configured to generate a signal to operate throttle by actuation of an actuator mounted on a throttle body.
In an embodiment, the magnet is potted with epoxy.
In an embodiment, the return plunger is defined with a surface configured to maintain a line contact with the cover.
In an embodiment, the return plunger (4) is an insert moulded with metal to increase durability.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The novel features and characteristics of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following detailed

description of an illustrative embodiments when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:
Figure 1 illustrates exploded view of a throttle actuation device for a vehicle in accordance with an embodiment of the present disclosure.
Figure 2 illustrates a sectional view of the throttle actuation device with a throttle grip in zero position, in accordance with an embodiment of the present disclosure.
Figure 3 illustrates a perspective view of a housing of the throttle actuation device in accordance with an embodiment of the present disclosure.
FIG. 4 illustrates a sectional view of the housing indicating full throttle condition of the throttle grip in accordance with an embodiment of the present disclosure.
FIG. 5 illustrates sectional side view of the housing having a magnet of figure 4, in accordance with an embodiment of the present disclosure.
FIG. 6 illustrates a sectional view of the throttle actuation device indicating rotation of the throttle grip in a reverse direction, in accordance with an embodiment of the present disclosure.
The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the apparatus and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION

While the embodiments in the disclosure are subject to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
It is to be noted that a person skilled in the art would be motivated from the present disclosure and modify construction of a throttle actuation device for a vehicle. However, such modifications should be construed within the scope of the disclosure. Accordingly, the drawings show only those specific details that are pertinent to understand the embodiments of the present disclosure, so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
The terms "comprises," "comprising," or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusions, such that an apparatus that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such apparatus, or device. In other words, one or more elements in apparatus proceeded by "comprises... a" does not, without more constraints, preclude the existence of other elements or additional elements in the system or device.
The following paragraphs describe the present disclosure with reference to Figures 1 to Figure 6. In the figures, the same element or elements which have similar functions are indicated by the same reference signs. Referring to Figure 1 to Figure 6 which are exemplary embodiments of the present disclosure illustrating a throttle actuation device (100) for a vehicle [interchangeably referred as "device"].

The throttle actuation device (100) a vehicle includes a throttle grip (T), a housing (1), rotor (2), torsion spring (3), a magnet (12), a magnetic sensor (9), a cover (8), a friction mechanism (20) and a cruise mode cancel mechanism (30).
The throttle grip (T) is an elongated member rotatably installed on a handlebar of the vehicle (or a motorcycle) such that a rider can grab the throttle grip (T) and rotate it for controlling speed of the vehicle. The throttle grip (T) may be rotated about the handlebar from an zero position in a normal direction (say, counter-clockwise), and in a reverse direction (say, clockwise) which is the opposite direction to the normal direction. The zero position of the throttle grip represents an idle condition of the vehicle where an engine of the vehicle is running but the vehicle is not in motion. In an embodiment, when the throttle grip (T) is rotated in normal direction then the vehicle accelerates in forward direction, and when the throttle grip (T) is rotated in reverse direction then the cruise mode cancel mechanism (30) is deactivated.
The housing (1) along with the cover (8) forms a casing to accommodate various components that constitute the throttle actuation device (100) such as the rotor (2), the torsion spring (3), the friction mechanism (20) and the cruise mode cancel mechanism (30). The housing (1) is a hollow body mounted about the shaft of the handlebar of the vehicle, adjoining the throttle grip (T).
The rotor (2) is rotatably disposed within the housing (1) and the rotor (2) is rotatably connected to the throttle grip (T). The rotor (2) is configured to rotate within the housing (1) based on rotation of the throttle grip (T). The rotor (2) is substantially circular in shape with a through hole about which the rotor (2) is installed on the handlebar. The rotor (2) includes integrally formed protrusions extending outward along the direction of the handlebar. These protrusions form two contact surfaces (2b) and (2c) adapted to selectively couple with a projection (Tl) extending radially from the throttle grip (T). Further, these protrusions form a plurality of depressions (2d) and (2e) provided substantially opposite to each other to engage with corresponding projections (not shown) provided at the throttle

grip (T) thereby enables the rotor (2) to rotate in conjunction with the throttle grip (T). The projection (Tl) defined on the throttle grip (T) is adapted to come in contact with the contact surface (2b) of the rotor (2) to actuate rotation of the rotor (2) in the normal direction. Similarly, the projection (Tl) is adapted to contact the contact surface (2c) of the rotor (2) to actuate the rotor (2) in the reverse direction. In an embodiment of the present disclosure, as shown in figure 3, when the rider rotates the throttle grip (T) in reverse direction, the throttle grip (T) is adapted to come in contact with the contact surface (2c) of the rotor (2) thereby actuating the rotor (2) rotation in reverse direction. As shown in Figure 3, in an assembled condition of the device (100), the protrusions of the rotor (2) having contact surfaces (2b) and (2c) extend about the cover (8). Further, a slot is defined around the protrusions of the rotor (2) to accommodate the torsion spring (3).
The torsion spring (3) is disposed with in the housing (1) as shown in Figure 2, and more particularly within the slot formed around the protrusions of the rotor (2). The torsion spring (3) has a first end attached to the housing (1) and a second end attached to a contact part (2h) of the rotor (2). The torsion spring (3) is configured to bias the rotor (2) toward the zero position when the throttle grip rotates (T) in at least one of normal. In other words, when the throttle grip (T) is rotated in the normal direction with certain torque and when the torque is removed, the torsion spring (3) exerts a biasing force on the throttle grip (T) returns the throttle grip (T) to the zero position.
The friction mechanism (20) is disposed within the housing (1) and adjacent to the rotor (2). Components of the friction mechanism (20) are interposed between an interior of the housing (1) and the rotor (2). The friction mechanism (20) includes a friction spring (6) in a compressed condition secured to the housing (1) and a friction plunger (7) loaded by the friction spring (6) onto the rotor (2) to oppose rotation of the rotor (2) in the normal direction. In an embodiment, the friction plunger (7) is configured to be in continuous contact with an outer peripheral surface (2a) the rotor (2) and oppose rotation of the rotor (2) in the normal direction. A friction force is generated between a contact surface (7a) of

the friction plunger (7) and the rotor surface (2a) of rotor (2) enables the rider to rotate and maintain the throttle grip (T) at a desired position in the normal direction with minimum stress on the rider's wrist. The friction mechanism (20) provides a tactile feel to the rider while operating the throttle grip (T) unlike conventional throttle grip.
Additionally, as shown in figure 4, the housing (1) is defined with a positive stopper (lb) adjacent to the friction plunger (7), wherein the positive stopper (lb) is adapted to about a rotor surface (2f) and restrict the rotation of the throttle grip (T) and rotor (2) in the normal direction. In an embodiment the positive stopper (lb) is adapted to abut the rotor surface (2f) at a maximum rotation of at least one of the rotor (2) and the throttle grip (T) in normal direction. Further, the positive stopper (lb) prevents the magnet disposed on the rotor (2) to come to contact with the friction plunger (7) and/or the friction spring (6).
The magnet (12) is disposed on the rotor (2), and the magnet (12) rotates along with the rotor (2). In an embodiment, an arc shaped magnet (12) is disposed on the rotor (2). The magnet (12) is potted with epoxy to save it from environmental changes or anomalies. Further, the magnetic sensor (9) is arranged within the housing (1) and configured generate a signal corresponding to variation in the magnetic field based on rotation of the magnet (12) due to rotation of the throttle grip (T). The magnetic sensor (9) is configured to detect a change in the magnetic field from the magnet (12) and detects a rotation angle of the throttle grip (T). Thereby, a position of the throttle in the engine of the vehicle is adjusted based on the signal generated by the magnetic sensor (9) for controlling speed of the vehicle. The magnetic sensor (9) is disposed on a printed circuit board (10) operated by a power from an electronic control unit (ECU). The PCB is in connection with a connector (14) to form a connection with the power source. In an embodiment the ECU is coupled to a battery of the vehicle or an independent battery source. In embodiment of the present disclosure, a PCB cover (11) is provided to protect the PCB. The throttle actuation device (100) further includes a throttle angle sensor configured to change the throttle position based on the signals corresponding to variation in the magnetic field.

The throttle actuation device (100) further includes a cruise mode cancel mechanism (30) configured to cancel or exert a biasing force on the throttle grip (T) during the rotation of throttle grip (T) by the rider in the reverse direction. When throttle is rotated in reverse direction against the return spring force, an electrical signal is generated which deactivates the cruise mode. The cruise mode cancel mechanism (30) is disposed within a circular guide of the housing (1) and adjacent to the rotor (2). The cruise mode cancel mechanism (30) comprises a return spring (5) secured at one end with the housing (1) and another end coupled to a return plunger (4). As shown in figure 6, the return plunger (4) is adapted to contact an extended portion (2g) of the rotor (2) at the zero position and exert a biasing force during rotation of the throttle grip (T) towards the reverse direction. As shown in figures 2 and 3, the return plunger (4) is radially guided in the circular guide so that it will not mis-align during operation of the throttle actuation device (100). Moreover, a surface (4a) of the return plunger (4) maintains a line contact (minimal frictional butting surface), with the cover (8) thus achieves less wear between interacting faces and provides a smooth feel to the rider and long reliable life of the device (100).
In an embodiment of the present disclosure, a mechanical stopper (lc) is disposed in the housing (1) adapted to abut the rotor surface (2f) at a maximum rotation of at least one of the rotor (2) and the throttle grip (T) in the reverse direction. In an embodiment of the present disclosure, as shown in figure 2, a position stopper (la) disposed in the housing (1) to the limit the movement of return plunger (4) under influence of return spring force. In an embodiment of the present disclosure, the return plunger (4) may be an insert moulded with metal to increase the durability as alternate design.
In an embodiment of the present disclosure, housing (1) is fixed with the cover (8) using fastening member (13) accommodating various components that constitute the throttle actuation device (100). The fastening member (13) is at least one of a nut, a screw, a bolt, threaded washer, a rivet, grommet or any fasteners in combination that serves the purpose.

In an embodiment of the present disclosure, the material for manufacturing the device (100) is at least one of aluminium, copper, steel, plastic, fibre-reinforced plastic, alloys or any other material that serves the purpose.
In an embodiment of present disclosure, the handlebar comprises at least one of a solid shaft, a hollow shaft, a clip-on handlebar or any other handlebar configuration which serves the purpose of mounting a switch assembly and steering of the vehicle. In an embodiment of the present disclosure, the handlebar is at least one of plastic, fibre-reinforced plastic, metal, wood, alloy or any other material that serves the purpose.
The device (100) as disclosed in the present disclosure can be packaged in a switch handle bar design or in standalone module as per the application requirement.
The device (100) in accordance with the present disclosure is economical to manufacture, easy to assemble and less time consuming to for manufacturing and assembly with respect to existing arts. The above- disclosed configuration of elements of throttle actuating device (100) is simple and compact. Further, the device (100) eliminates a need of special arrangement for rotor operation.
The device (100) in accordance with the present disclosure includes both friction mechanism (20) and cruise mode cancel mechanism (30). This enables the rider to rotate and maintain the throttle grip (T) at a desired position in the normal direction, with minimum stress on the rider's wrist. Moreover, this results in smooth movement of the throttle in reverse direction for cruise mode cancellation.
It is to be understood that a person of ordinary skill in the art may develop an apparatus of similar configuration without deviating from the scope of the present disclosure. Such modifications and variations may be made without departing from the scope of the present invention. Therefore, it is intended that the present disclosure covers such modifications

and variations provided they come within the ambit of the appended claims and their equivalents.
Equivalents:
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations.
In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other

modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
List of reference numeral

Numeral Particular
100 Throttle actuation device
1 housing
la Position stopper
lb Positive stopper

lc Mechanical stopper
2 Rotor
2a Outer peripheral surface
2b Contact surface
2c Contact surface
2d Plurality of depressions
2e Plurality of depressions
2h Contact part
2f Peripheral rotor surface
2g Extended portion
3 Torsion spring
4 Return plunger
4a Surface of return plunger
5 Return Spring
6 Friction Spring
7 Friction Plunger
7a Contact surface of Friction plunger
8 Cover
9 Magnetic Sensor
10 Printed circuit Board
11 PCB Cover
12 Magnet
13 Fastening Means
14 Connector
20 Friction mechanism
30 Cruise mode cancel mechanism

T Throttle Grip
Tl Projection of the throttle grip

We Claim:

1. A throttle actuation device (100) for a vehicle, comprising:
a throttle grip (T) rotatable from a zero position towards at least one of a normal direction and a reverse direction;
a rotor (2), rotatably disposed within a housing (1), the rotor (2) is connectable to the throttle grip (T), and being configured to rotate within the housing (1) based on rotation of the throttle grip (T);
a torsion spring (3) having a first end attached to the housing (1) and a second end attached to the rotor (2), wherein the torsion spring (3) is configured to bias the rotor (2) toward the zero position when the throttle grip rotates (T) in normal direction;
a friction mechanism (20), disposed within the housing (1) and adjacent to the rotor (2), the friction mechanism (20) comprising a friction spring (6) secured to the housing (1) and a friction plunger (7) loaded by the friction spring (6) onto the rotor (2) and oppose rotation of the rotor (2) in the normal direction;
a magnet (12) disposed on the rotor (2), wherein the magnet (12) rotates along with the rotor (2); and
a magnetic sensor (9), disposed within the housing (1), and configured generate a signal corresponding to variation in the magnetic field based on rotation of the throttle grip (T), wherein, a throttle position is adjusted based on the signal corresponding to variation in the magnetic field.
2. The throttle actuation device (100), comprises a cruise mode cancel mechanism
(30), disposed within a circular guide of the housing (1) and adjacent to the rotor

(2), wherein the cruise mode cancel mechanism (30) comprises a return spring (5) secured at one end with the housing (1) and another end coupled to a return plunger (4), wherein the return plunger (4) is adapted to contact an extended portion (2g) of the rotor (2) at the zero position and reverse rotation of the throttle grip (T) generates a cruise mode deactivation signal for cancellation.
3. The throttle actuation device (100) as claimed in claim 1, wherein the housing (1) is defined with a positive stopper (lb) adjacent to the friction plunger (7), wherein the positive stopper (lb) is adapted to abut a rotor surface (2f) and restrict the rotation of the throttle grip (T) and rotor (2) in the normal direction.
4. The throttle actuation device (100) as claimed in claim 1, comprises a projection (Tl) extending radially from the throttle grip (T) is adapted to contact a contact surface (2c) of the rotor (2) to actuate the rotor (2) in normal and the reverse direction.
5. The throttle actuation device (100) as claimed in claim 1, wherein the projection (Tl) defined on the throttle grip (T) is adapted to come in contact with a contact surface (2b) of the rotor (2) to actuate rotation of the rotor (2) in the normal direction.
6. The throttle actuation device (100) as claimed in claim 1 to 2, comprises a cover (8) coupled to the housing (1) to enclose the rotor (2), the torsion spring (3), the friction mechanism (20), the cruise mode cancel mechanism (30), the magnet (12) and the magnetic sensor (9) within the housing (1).

7. The throttle actuation device (100) as claimed in claim 1, wherein the magnetic sensor (9) is disposed on a printed circuit board (10) operated by a power supplied to an electronic control unit (ECU).
8. The throttle actuation device (100) as claimed in claim 7, wherein the electronic control unit (ECU) is coupled to a battery of the vehicle.
9. The throttle actuation device (100) as claimed in claim 1, wherein magnetic sensor (9) is configured to generate a signal to operate throttle by actuation of an actuator mounted on a throttle body.
10. The throttle actuation device (100) as claimed in claim 1, wherein the magnet (12) is potted with epoxy.
11. The throttle actuation device (100) as claimed in claim 2 to 6, wherein the return plunger is defined with a surface (4a) configured to maintain a line contact with the cover (8).
12. The throttle actuation device (100) as claimed in claim 2, wherein the return plunger (4) is an insert moulded with metal to increase durability.