Description:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
A DISC BRAKE ASSEMBLY OF A VEHICLE

Applicant:
River Mobility Private Limited
A company based in India,
Having its address as:
No. 25/3, KIADB EPIP Zone, Seetharampalya, Hoodi Road, Mahadevapura, Whitefield, Bengaluru, Karnataka, India- 560048

The following specification describes the invention and the manner in which it is to be performed.

PRIORITY INFORMATION
The present application is a patent of addition claiming priority from the parent application no. 202341045160 filed on 05th July, 2023.

FIELD OF INVENTION
The present invention generally relates to a brake assembly. More specifically, the present invention is related to a disc brake assembly.

BACKGROUND OF THE INVENTION
The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also correspond to implementations of the claimed technology.
Pressure transducers are widely used for measuring pressure across different systems. Based on pressure values measured by the pressure sensors, different operations of the systems are managed. This technology is commonly used for the measurement of highly dynamic pressure in a system. These sensors are used in many applications, such as in hydraulic as well as pneumatic systems.
Fig. 1 illustrates a front view of a conventional pressure sensor 100, in accordance with prior-art. The conventional pressure sensor 100 includes a housing/casing 102 including a pressure sensing element. An input-output cable 104 connected at one end of the conventional pressure sensor 100 powers the sensing element. At another end of the conventional pressure sensor 100, male threads 106 are present. With the help of such male threads 106, the conventional pressure sensor 100 is secured with an adaptor which may have female threads. The conventional pressure sensor 100 secured with the adaptor is then mounted over a system in which pressure is required to be measured. Therefore, the conventional pressure sensor 100 requires integration with additional components, such as the adaptor for mounting over a system, to measure the pressure. This increases the manufacturing process and assembly of components, and associated costs. Further, integration and disintegration of such components during installation or repairing also reduces their operational life.
In view of the above mentioned shortcomings, there arises a need for a pressure sensor which doesn’t require any additional components for fitment, has lower cost, and whose installation is quick and easy.
In an electrical vehicle, a range i.e. distance that could be covered by the electric vehicle before next recharging depends mainly on a total energy capacity of its battery pack. Optimising energy efficiency of the battery pack to a maximum extent is crucial for extracting the best possible range. One way to improve the energy efficiency is to regenerate mechanical energy lost during braking by turning the motor of the electric vehicle into a generator, thereby recharging the battery pack.
Some conventional mechanisms utilize a passive regeneration strategy where a set amount of regeneration current is regenerated into the battery pack during braking with respect to the speed of the motor. Such a strategy does not take into account a state of the battery pack or an amount of braking energy requested by an operator of the electric vehicle. Also, a single passive map is optimised for all modes of operation of the electric vehicle, such as under heavy loaded conditions, climbing steep gradients/slopes, and traffic conditions. As a result, the single passive map does not recover the braking energy to a maximum possible extent possible under different road conditions.
Other conventional mechanisms utilize force sensors or pressure sensors for determining braking force applied by an operator of an electric vehicle, and regeneration current is regenerated based on the outputs of such sensors. Such sensors are typically attached to mechanical systems such as ends of brake levers/push rods, end of master cylinder, brake pedals, or between brake hoses. Due to such arrangement of the sensors, there exists a time delay between
application of brakes by an operator and actuation of brake calipers. Further, such sensors aren’t able to capture direct and precise values of braking force.
Therefore, there arises a need for a braking system which can directly and precisely detect the braking force applied by an operator of the vehicle and generate regeneration current based on such braking force.

OBJECTS OF THE INVENTION
A general objective of the invention is to provide a pressure sensor which doesn’t require additional components for its fitment with a system.
Another objective of the invention is to provide a pressure sensor having optimized cost, size, and weight.
Yet another objective of the invention is to provide a pressure sensor which can be installed quickly and easily.
Still another objective of the invention is to provide a pressure sensor having a large operational life.
Still another objective of the invention is to mount a pressure sensor at an end of a caliper assembly for accurate and direction detection of braking force.
Still another objective of the invention is to produce a maximum possible amount of regeneration current based on the measured pressure, and operating conditions of the vehicle and its components.

SUMMARY OF THE INVENTION
This summary is provided to introduce aspects related to a pressure sensor, and the aspects are further described below in the detailed description. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.
In one embodiment, a pressure sensor comprises a sensing element positioned within a housing, and a banjo connector extending from a first end of the housing and an input-output cable extending from a second end of the housing. The input-output cable electrically powers the sensing element. The banjo connector allows connection of the pressure sensor with a system in which pressure is to be determined, and the sensing element senses the pressure.
In one aspect, the banjo connector is an integral part of the pressure sensor.
In one aspect, the sensing element senses the pressure through change in capacitance, inductance, or resistance.
In one aspect, the system is a pneumatic system or a hydraulic system.
In one aspect, the input-output cable communicates an amount of the measured pressure as a digital signal or an analog signal.
In one aspect, the second end of the housing is covered with a waterproof seal or a potting compound.
In one embodiment, a disc brake assembly of a vehicle comprises a pressure sensor integrated with a caliper assembly for determining a pressure corresponding to a braking force applied by an operator of the vehicle. The pressure sensor is integrated with the caliper assembly using a double banjo bolt.
In one aspect, the pressure sensor includes a sensing element positioned within a housing, and a banjo connector extending from a first end of the housing. The banjo connector allows connection of the pressure sensor with the caliper assembly, and the sensing element senses the pressure.
In one aspect, a second end of the housing connects with an input-output cable electrically powering the sensing element.
In one aspect, the double banjo bolt has an axial cavity, and a first hole and a second hole present at different positions on its lateral surface. The double banjo bolt allows fitment of a brake hose along the first hole and fitment of the pressure sensor along the second hole. The double banjo bolt distributes brake fluid received from the brake hose towards the caliper assembly through the axial cavity upon activation of brakes. The pressure sensor through the second hole for measurement of the pressure.
In one aspect, the pressure sensor measures the sensed pressure through change in capacitance, inductance, or strain.
In one aspect, an amount of measured pressure is provided as an input to a vehicle control unit either as a digital signal or an analog signal.
In one aspect, the vehicle is an electric vehicle or an internal combustion engine driven vehicle.
In one aspect, the pressure sensor is fitted along the second hole of the double banjo bolt through an adaptor.
In one aspect, the amount of the measured pressure is provided as an input to a vehicle control unit. The vehicle control unit determines an amount of regeneration current based on the amount of the measured pressure and one or more vehicle operational parameters. The one or more vehicle operational parameters include battery pack state of charge, battery pack temperature, motor temperature, battery pack maximum current limit, speed of vehicle, and an estimated load of the vehicle.
In one aspect, a motor control unit receives, from the vehicle control unit, a signal to produce the amount of the regeneration current by operating a motor of the vehicle in a generator mode. Further, a battery pack connected with the motor stores the regeneration current.
In one aspect, the regeneration current is the maximum amount of current that can be produced by a motor of the vehicle based on the amount of the measured pressure and the one or more vehicle operational parameters.
In one aspect, one or more motors coupled with one or more wheels of the vehicle are used for producing the regeneration current.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings constitute a part of the description and are used to provide a further understanding of the present invention.
Fig. 1 illustrates a front view of a conventional pressure sensor, in accordance with prior-art.
Figs. 2a and 2b illustrate front views of a pressure sensor, in accordance with an embodiment of the present invention.
Fig. 3 illustrates an actual image of the pressure sensor integrated with an input-output cable, in accordance with an embodiment of the present invention.
Fig. 4 illustrates a side perspective view of a disc brake assembly of a vehicle, in accordance with an embodiment of the present invention.
Fig. 5 illustrates a perspective top view of a top half of the disc brake assembly, in accordance with an embodiment of the present invention.
Fig. 6a illustrates an exploded perspective top view of a bottom half of the disc brake assembly, in accordance with an embodiment of the present invention.
Fig. 6b illustrates an exploded side view of the bottom half of the disc brake assembly, in accordance with an embodiment of the present invention.
Fig. 7a illustrates a sectional side view of a double banjo bolt and Fig. 7b illustrates a sectional front view of the double banjo bolt, in accordance with an embodiment of the present invention.
Fig. 8 illustrates a block diagram of an energy regeneration system, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION
The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. Each embodiment described in this disclosure is provided merely as an example or illustration of the present invention, and should not necessarily be construed as preferred or advantageous over other embodiments. The detailed description includes specific details for the purpose of providing a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.
The present invention pertains to a pressure sensor comprising a sensing element positioned within a housing and a banjo connector extending from a first end of the housing. An input-output cable extends from a second end of the housing, and the input-output cable electrically powers the sensing element. The banjo connector allows connection of the pressure sensor with a system in which pressure is to be determined.
Figs. 2a and 2b illustrate front views of a pressure sensor 200, in accordance with an embodiment of the present invention. The pressure sensor 200 includes a sensing element positioned within a housing 202. The pressure sensor 200 further includes a banjo connector 204 extending from a first end 206 of the housing 202. The banjo connector 204 is an integral part of the pressure sensor 200. An input-output cable extends from a second end 208 of the housing 202. Further, the second end 208 of the housing 202 may be covered completely with a waterproof seal or a potting compound. The potting compound may also be used to completely fill the inside of the housing 202 for providing the pressure sensor 200 resistance to shock and vibration, and for exclusion of water, moisture, or corrosive agents. The potting compound may be a thermosetting plastic, silicone rubber gel, or an epoxy resin.
The input-output cable supplies electrical power to the sensing element, for example through a battery. The banjo connector 204 allows connection of the pressure sensor 200 with a system in which pressure is to be determined. Once the pressure sensor 200 is connected with the system, the sensing element senses the pressure in the system. The pressure sensor 200 may utilize different types of sensing elements, for example capacitance, inductance, or resistance based sensing elements. Based on a change in value of the capacitance, the inductance, or the resistance, the pressure sensor 200 measures the pressure. The input-output cable may communicate an amount of measured pressure as a digital signal or an analog signal to a required unit, for example a control unit responsible for activating brakes in a vehicle. An overall length of the pressure sensor 200 may be defined during fabrication of the pressure sensor 200 to suit a final application. In preferred implementations, the overall length may range from 30mm to 150mm.
The pressure sensor 200 may be used for measuring pressure in pneumatic or hydraulic systems. The pneumatic systems may include, but not limited to, vehicle tyres, compressors, compressed-air engines, and vacuum pumps, industrial gas storage systems, and air brakes used in buses, trucks, trains, large vehicles such as trucks, buses, trailers, semi-trailers, and railroad trains. The hydraulic systems may include, but not limited to, hydraulic brakes, fuel pressure lines, water pressure measurement systems, oil pressure gauges, power steering systems, shock absorbers, utility vehicles such as excavators and aerial platforms, lifts and industrial machinery such as hydraulic press, mobile hydraulics, and diesel and gas engines.
Fig. 3 illustrates an actual image of the pressure sensor 200 integrated with an input-output cable, in accordance with an embodiment of the present invention. From Fig. 3 and the details provided above, it must be understood that the proposed pressure sensor (the pressure sensor 200) has an integrated structure and doesn’t require additional components for its fitment with a system in which pressure is required to be determined. Such integrated structure of the proposed pressure sensor overcomes the need of using different components that are generally required along with conventional pressure sensors, such as an adaptor. Further, the integrated structure of the proposed pressure sensor also eliminates the need of threaded and sealing connections generally required for joining conventional pressure sensors with their adaptors. Also, the process of joining a threaded end with a housing/body of the pressure sensor is avoided. Because of using the least number of components, the proposed pressure sensor has a more compact design, can be installed quickly and easily, has an optimized length, cost, size, weight, and a large operational life.
Fig. 4 illustrates a side perspective view of a disc brake assembly 400 of a vehicle, in accordance with an embodiment of the present invention. Specifically, Fig. 4 illustrates a Combined Braking System (CBS) including two disc brake assemblies of a 2-wheeled vehicle, one for a front wheel and another for a rear wheel. In some implementations, the disc brake assembly 400 could be provided only for a single wheel of the vehicle. Further, it must be understood that similar arrangements could be extended to a 3-wheeled vehicle, a 4-wheeled vehicle, or a vehicle running on more number of wheels. The 2-wheeled vehicle (alternatively referred to as the vehicle) is an electric vehicle, an internal combustion engine driven vehicle, or a hybrid electric vehicle. The disc brake assembly 400 includes a right brake lever 402a and a left brake lever 402b (cumulatively referred as brake levers 402a, 402b) operable by hands of an operator of the 2-wheeled vehicle. The right brake lever 402a is connected with a caliper assembly 404a to be installed on the front wheel. As Fig. 4 illustrates the CBS, it could be seen that the left brake lever 402b is connected with the caliper assembly 404a, and a caliper assembly 404b to be installed on the rear wheel. Therefore, front disc brakes could be activated upon operation of the right brake lever 402a and the front disc brakes as well as rear disc brakes could be activated upon operation of the left brake lever 402b. In a 3-wheeled vehicle, 4-wheeled vehicle, or other n-wheeled vehicle, the brake levers 402a, 402b may be replaced with a brake pedal for activation of the disc brakes through a foot of the operator.
For ease of explanation, arrangement of components and functioning of the disc brake assembly 400 provided on the rear wheel, including the left brake lever 402b and the caliper assembly 404b, has been described successively with reference to Fig. 5, Fig. 6a, and Fig. 6b.
Fig. 5 illustrates a perspective top view of a top half of the disc brake assembly 400, in accordance with an embodiment of the present invention. In one implementation, the left brake lever 402b may be connected with a brake pump. The brake pump may be connected with a reservoir tank 502 storing a hydraulic brake fluid. A brake hose 504 is connected with the reservoir tank 502 using a banjo connector 506 and a banjo bolt 508. Further, a brake hose 510 is connected with the reservoir tank 502 using a banjo connector 512 and the banjo bolt 508. The brake hose 504 carries the brake fluid towards the caliper assembly 404b and brake hose 510 carries the brake fluid towards the caliper assembly 404a. Additionally, one or more washers 514a, 514b may be used for leak-proof integration of the brake hoses 504, 510 with the reservoir tank 502.
Fig. 6a illustrates an exploded perspective top view of a bottom half of the disc brake assembly 400, in accordance with an embodiment of the present invention. Fig. 6b illustrates an exploded side view of the bottom half of the disc brake assembly 400, in accordance with an embodiment of the present invention.
The brake hose 504 connected with the reservoir tank 502 at one end is connected with the caliper assembly 404b at the other end. The brake hose 504 is connected with the caliper assembly 404b using a banjo connector 602 and a double banjo bolt 604. Further, the pressure sensor 200 is integrated with the caliper assembly 404b using the double banjo bolt 604. Specifically, the pressure sensor 200 is integrated with the double banjo bolt 604 using the banjo connector 204. In an alternate implementation, the pressure sensor 200 may be integrated with the double banjo bolt 604 using an adaptor instead of the banjo connector 204. It must be noted that any other pressure sensor having a different shape and operational mechanism from that of the pressure sensor 200 could be integrated with the caliper assembly 404b.
The double banjo bolt 604 has an axial cavity, and a first hole 606a and a second hole 606b present at different positions on its lateral surface. Fig. 7a illustrates a sectional side view of a double banjo bolt and Fig. 7b illustrates a sectional front view of the double banjo bolt, in accordance with an embodiment of the present invention. The double banjo bolt 604 allows fitment of the brake hose 504 along the first hole 606a and fitment of the pressure sensor 200 along the second hole 606b. Alternatively, the brake hose 504 may be fitted along the second hole 606b and the pressure sensor 200 may be fitted along the first hole 606a. Additionally, washers 608a, 608b, 608c may be used for leak-proof integration of the brake hose 504 and the pressure sensor 200 with the double banjo bolt 604.
To apply brakes, the operator presses the left brake lever 402b, and the left brake lever 402b pushes the brake pump. Successively, the brake pump pushes the brake fluid through the brake hose 504 towards the caliper assembly 404b, for pressing brake pads against a moving disc fixed at the rear wheel. The brake fluid is distributed towards the caliper assembly 404b through the first hole 606a and then through the axial cavity of the double banjo bolt 604. The brake fluid is also distributed towards the pressure sensor 200 through the second hole 606b of the double banjo bolt 604. From the distributed and compressed brake fluid, the pressure sensor 200 dynamically determines a pressure corresponding to a braking force applied by the operator.
In one implementation, electric energy may be regenerated based on the amount of pressure measured by the pressure sensor 200. Fig. 8 illustrates a block diagram of an energy regeneration system, in accordance with an embodiment of the present invention.
The amount of measured pressure may be provided by the pressure sensor 200 to a Vehicle Control Unit (VCU) 802 either as a digital signal or an analog signal. The VCU 802 determines an amount of regeneration current based on the amount of the measured pressure and one or more vehicle operational parameters. The one or more vehicle operational parameters may include, but not limited to, battery pack state of charge, battery pack temperature, motor temperature, battery pack maximum current limit, speed of vehicle, and an estimated load of the vehicle. The one or more vehicle operational parameters may be captured using different sensors integrated with the vehicle. For example, a temperature sensor mounted on a battery pack of the vehicle may determine the battery pack temperature. Further, an accelerometer or a speedometer may determine the speed of the vehicle. A Battery Management System (BMS) 804 connected with the VCU 802 may determine the battery pack state of charge. A Motor Control Unit (MCU) 806 connected with the VCU 802 may determine motor parameters, such as the motor temperature and a motor speed, and provide the motor parameters to the VCU 802.
The VCU 802 may provide a signal to the MCU 806 to produce the amount of the regeneration current by operating a motor 808 coupled with a wheel of the vehicle in a generator mode. Similarly, additional motors coupled with other wheels of the vehicle may also be used for producing the regeneration current. The regeneration current may be a maximum amount of current that can be produced by the motor 808 of the vehicle based on the amount of the measured pressure and the one or more vehicle operational parameters. A battery pack 810 connected with the motor 808 stores the regeneration current.
In one implementation, a maximum current acceptance limit of the battery pack 810 may be 50A. In one scenario, the VCU 802 may determine that the regeneration current that can be generated based on the measured pressure and the one or more vehicle operating parameters is 45A. In such a scenario, the VCU 802 may send a signal to the MCU 806 for operating the motor of the vehicle in the generator mode to generate 45A current. In another scenario, the VCU 802 may determine that the regeneration current that can be generated based on the measured pressure and the one or more vehicle operating parameters is 55A. In such a scenario, the VCU 802 may send a signal to the MCU 806 for operating the motor of the vehicle in the generator mode to generate 50A current as the maximum current acceptable limit of the battery pack is 50A.
Above proposed pressure sensor could be retrofitted with existing caliper assembly i.e. brake caliper using the double banjo bolt. New brake calipers could be designed to provide provisions for integrations of the pressure sensor. In the above described arrangements, since the pressure sensor is mounted at ends of a caliper assembly, a time delay between application of brakes at lever end and engagement of braking pads of the disc brakes remains negligible. Further, pressure drop arising due to lever stiffness, brake line flexure, and compressibility of the brake fluid is negated in the above described arrangements. The pressure sensor mounted at the brake calliper ends accurately and directly measures the braking force applied by the operator for vehicle deceleration and hence, any wear and tear related drop in pressure is also negated. The pressure sensor can also detect any leakage in the braking system. Also, the use of pressure sensors at the brake calliper end ensures accurate measurement of brake pressure and offers repeatability over time. Further, as the pressure sensor directly measures the braking force applied by the operator, the VCU isn’t required to perform complex computations, such as for determining an offset arising due to mechanical losses.
Above proposed braking system is more reliable compared to conventional braking systems for determining braking force for example, the ones using an Anti-lock Braking System (ABS) sensor, brake pedal stroke sensor, brake pedal sensor, force sensor, or any other brake sensor. In conventional braking systems, any damage to components associated with the braking can go unnoticed i.e., for example, when any of the above mentioned sensors fail, regeneration of brake energy will fail however, the brakes would still work. However, in the proposed braking system, the likelihood of failure of the pressure sensor is very low as the pressure sensor is connected directly with a critical part of the braking system i.e., the brake caliper.
The pressure sensor determines pressure demand from an operator and the VCU determines a proportional generator torque for the motor acting as a generator, based on operating conditions of the vehicle and its components. The VCU signals the MCU to cause the motor to generate the required torque (i.e., current) in a generator mode to produce a maximum possible amount of regeneration current. As the VCU considers the operating conditions of the vehicle and its components for production of a maximum possible amount of regeneration current, safety of the vehicle, battery pack, and other components is ensured.
Although implementations of the disc brake assembly have been described in language specific to structural features and/or methods, it is to be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features or methods are disclosed as examples of implementations of the disc brake assembly.
, C , Claims:We Claim:
1. A disc brake assembly (400) of a vehicle, comprising:
a pressure sensor (200) integrated with a caliper assembly (404a, 404b) for determining a pressure corresponding to a braking force applied by an operator of the vehicle, wherein the pressure sensor (200) is integrated with the caliper assembly (404a, 404b) using a double banjo bolt (604).

2. The disc brake assembly (400) as claimed in claim 1, wherein the pressure sensor (200) includes:
a sensing element positioned within a housing (202); and
a banjo connector (204) extending from a first end (206) of the housing (202), wherein the banjo connector (204) allows connection of the pressure sensor (200) with the caliper assembly (404a, 404b), and the sensing element senses the pressure.

3. The disc brake assembly (400) as claimed in claim 2, wherein a second end (208) of the housing (202) connects with an input-output cable electrically powering the sensing element.

4. The disc brake assembly (400) as claimed in claim 3, wherein the second end (208) of the housing (202) is covered with a waterproof seal or a potting compound.

5. The disc brake assembly (400) as claimed in claim 1, wherein the double banjo bolt (604) has an axial cavity, and a first hole (606a) and a second hole present (606b) at different positions on its lateral surface, the double banjo bolt (604) allows fitment of a brake hose (504) along the first hole (606a) and fitment of the pressure sensor (6200) along the second hole (606b),
and wherein the double banjo bolt (604) distributes brake fluid received from the brake hose (504) towards the caliper assembly (404b) through the axial cavity upon activation of brakes,
and the pressure sensor (200) through the second hole (606b) measures the pressure.

6. The disc brake assembly (400) as claimed in claim 1, wherein the pressure sensor (200) measures the sensed pressure through change in capacitance, inductance, or strain.

7. The disc brake assembly (400) as claimed in claim 1, wherein an amount of the measured pressure is provided as an input to a vehicle control unit (802) either as a digital signal or an analog signal.

8. The disc brake assembly (400) as claimed in claim 1, wherein the vehicle is an electric vehicle or an internal combustion engine driven vehicle.

9. The disc brake assembly (400) as claimed in claim 1, wherein the pressure sensor (200) is fitted along the second hole (606b) of the double banjo bolt (604) through an adaptor.

10. The disc brake assembly (400) as claimed in claim 7, wherein the amount of the measured pressure is provided as an input to the vehicle control unit (802), and the vehicle control unit (802) determines an amount of regeneration current based on the amount of the measured pressure and one or more vehicle operational parameters including battery pack state of charge, battery pack temperature, motor temperature, battery pack maximum current limit, speed of vehicle, and an estimated load of the vehicle.

11. The disc brake assembly (400) as claimed in claim 10, wherein
a motor control unit (806) receives, from the vehicle control unit (802), a signal to produce the amount of the regeneration current by operating a motor (808) of the vehicle in a generator mode, and
a battery pack (810) connected with the motor (808) stores the regeneration current.

12. The disc brake assembly (400) as claimed in claim 10, wherein the regeneration current is the maximum amount of current that can be produced by a motor (808) of the vehicle based on the amount of the measured pressure and the one or more vehicle operational parameters.

13. The disc brake assembly (400) as claimed in claim 11, wherein one or more motors (808) coupled with one or more wheels of the vehicle are used for producing the regeneration current.