WO2022172283A1

WO2022172283A1 - An electric machine

Info

Publication number: WO2022172283A1
Application number: PCT/IN2022/050071
Authority: WO
Inventors: Aravindakrishnan Srikumar; Krishnamurthy Harigovindh; Karuppaian ANUPAMA
Original assignee: Tvs Motor Company Limited
Priority date: 2021-02-12
Filing date: 2022-01-28
Publication date: 2022-08-18

Abstract

The present subject matter generally relates to an electric machine (800). The present subject matter specifically but not exclusively relates to a compact electric machine (800) and an integrated control unit (201) for the electric machine (800) of a compact type saddle type vehicle (100). The present subject matter specifically relates to an electric machine (800) such as an ISG machine which is integrated with a control unit e.g. an ISG controller enabling to maintain the axial length of the electric machine (800) even after accommodating the ISG controller. Present invention keeps the engine packaging and vehicle layout unaltered.

Description

AN ELECTRIC MACHINE

TECHNICAL FIELD

[0001] The present subject matter generally relates to an electric machine. The present subject matter specifically but not exclusively relates to a compact electric machine and an integrated control unit for the electric machine of a compact type saddle type vehicle.

BACKGROUND

[0002] A vehicle with an integrated starter-generator (ISG) system replaces separate use of a starter and an alternator and integrates both of them into a single electric device. The ISG system provides better fuel economy, electrical generation capacity and reduced emissions. ISG system also eliminates the requirement of a separate starter which remains in a passive state once an engine starts combustion and ISG system also provides fast control of a generator voltage during load dumps in order to improve the distribution power quality.

[0003] Generally, ISG machine is capable of generating electrical power by the method of electromagnetic induction in a plurality of coils that are wound around individual tooth of the stator of the ISG machine, which is caused due to the rotation of the rotor of the ISG machine. The rotor of the ISG machine is coupled to the crankshaft of the IC engine, and the rotor of the ISG machine rotates along with the rotation of the crankshaft of the IC engine. The electrical power generated by the ISG machine is supplied to recharge any power source in a vehicle, for example, a battery through a rectifier circuit. The ISG machine functions in a generation mode when the power is transmitted to the power source.

[0004] But when the ISG machine is functioning in the motoring mode, the power is drawn from the battery and ISG machine provides a necessary assisting torque to the IC engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The detailed description is described with reference to an embodiment of an electric machine and an electric machine in a saddle type vehicle along with the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.

[0006] Fig. 1 illustrates a right-side view of an exemplary saddle-ride vehicle in accordance with the present subject matter.

[0007] Fig. 2 illustrates a bottom perspective view of the electric machine in accordance with the present subject matter. [0008] Fig. 3 illustrates a top view of electric machine in accordance with the present subject matter.

[0009] Fig. 4 illustrates a top view of the electric machine in accordance with the present subject matter.

[00010] Fig. 5 illustrates a top view and a bottom view of the electric machine in accordance with the present subject matter.

[00011] Fig. 6 illustrates a side cross-sectional view of the electric machine in accordance with the present subject matter.

[00012] Fig. 7 illustrates a block diagram of the electric machine integrated with a control unit in a circuit layout of the vehicle in accordance with the present subject matter.

DETAILED DESCRIPTION

[00013] In the existing vehicle layout, the ISG machine mounted on a crankshaft cranks the engine for a predetermined duration based on an ignition start switch input and subsequently the same ISG machine acts as a generator and provides the required power for charging a battery and other electric loads in the vehicle. For driving the ISG machine as a motor, a DC input power from the battery has to be converted into three phase AC output power using an ISG controller. During generation mode, the generated three phase AC output power from a ISG is converted into a DC output power using a rectifier and a regulator unit, which are integrated with the ISG controller. Positioning of the ISG controller in a vehicle is critical and the existing system provides ISG controller located away from the ISG machine which results in increased length of the wiring harness, which incurs additional loss and reduces system efficiency. The increased length of the wiring harness is more susceptible to wiring cut due to sharp edges or weld spots in frame which can result in a short circuit. In order to protect the wiring harness from getting damaged, additional corrugated tubes are used which increases the weight as well as adds to the cost and also leads to assembly difficulty. Further, placement of ISG controller on the vehicle frame, in addition to existing components, makes the overall packaging difficult and requires additional frame bracket to securely mount the ISG controller which adds to weight, number of parts as well as to the cost.

[00014] The ISG machine is generally dipped in oil in the engine and the wires routed from the ISG machine to the ISG controller, placed outside, need to be carefully taken out from a perforation provided in the body of the engine. It is important to make that perforation leakage free and hence a rubber seal keeps the perforation air tight. But if the engine is of high capacity, then the cross section of the wire connecting the ISG machine with other components also increases. This increase in the cross section of the wire also requires larger size of the perforation to be created on the surface of the engine body which increases the chances of oil leakage if any damage occurs. With wider perforation, the surface area for potential chance of leak increases and thus the oil tends to lead out quicker or in higher quantity from the engine body.

[00015] The increase in the cross-section area of the wires, especially the high power cables that connect the ISG machine to the ISG controller, for instance, due to an increase in the engine capacity of the vehicle, would require larger wire-out holes to be casted on the engine crankcase. An increase in size of such holes also increases the complexity with respect to sealing of oil passages in the crankcase. Thus, additional measures have to be taken for preventing oil leakage in such engines. This also leads to higher exposure of water entry especially when the wire-out zone is more proximal to ground level.

[00016] Further, providing an ISG controller in as per known methods increase the axial length of the electric machine which again requires modification in the vehicle layout as well as leads to undesirable increase in the size of the electric machine. Thus, there is a need to design an improved ISG machine which overcomes all problems cited and other problems of known art.

[00017] Therefore, the present subject matter discloses an improved electric machine such as an ISG machine which is integrated to a control unit e.g., an ISG controller and is configured to maintain the axial length of the electric machine even after accommodating the ISG controller. The Present invention keeps the engine packaging and vehicle layout unaltered as well as compact. The present invention also eliminates any additional frame bracket and its associates cost impact. Also, the present invention eliminates potential engine oil leakage which exists in the existing design.

[00018] Another embodiment of the present invention provides an electric machine with a control unit for controlling the electric machine in which the control unit is mounted circumferentially adjoining said back iron. The control unit is specifically located in between a crankcase of the vehicle and the stator of the electric machine. This design configures the space between the crankcase and the stator to dispose the control unit without altering the axial length of the rotating axis of the electric machine.

[00019] Yet another embodiment of the present invention provides an electric machine with a control unit in form of a circuit board with an outer diameter equal to or lesser than an outer diameter of said stator and thereby it helps in maintaining the packaging of the electric engine. This also eliminates the routing of wire harness out of the crankcase as both the electric machine and the control unit are integrated. Hence, no perforation required and thereby no issue of leakage of oil. [00020] Still another embodiment of the present invention provides an electric machine with a control unit which comprises a circuit board with electrical components such that the electrical components such as a capacitor and a choke coil is disposed axially within a stator slot located between said plurality of stator teeth. This layout of the electrical components optimises the spaces between the stator teeth and also maintains small axial length of the electric machine.

[00021] Another embodiment of the present invention provides an electric machine with a control unit with heat dissipating electric components, which are kept in physical contact with a lamination of the stator. The heat dissipating components are a MOSFET bridge, a bridge isolator, a buck converter, a MOSFET bridge unit. By bringing the lamination of the stator of the electric machine in physical contact with the heat dissipating components direct heat dissipation is achieved and any additional heat sink is eliminated. [00022] Fig. 1 illustrates a right-side view of an exemplary saddle-ride vehicle

(100) in accordance with the present subject matter. The saddle-ride vehicle (referred to as ‘vehicle’ for brevity) (100) includes a main frame structure (130) shown schematically with dotted lines, that acts a structural member of the vehicle (100). Further, the vehicle (100) comprises a front wheel (101) and a rear wheel (102). The present subject matter is not limited to the motor vehicle with two- wheels, as it is considered only for ease of explanation, and it is applicable for any saddle-ride vehicle. The main frame structure (130) includes a head tube (131), a main tube (132) and one or more rear tube(s) (133). In accordance with the current embodiment, the head tube (131) is disposed in a front portion of the vehicle (100). The main tube (132) extends rearward from the head tube (131) and the main tube (132) then forms a bending portion (134). Subsequent to the bending portion (134), the main tube (132) extends substantially downward. The one or more rear tube(s) (133) extend rearward from the bending portion (134). In one implementation, main tube (132) is a single tubular member. In another implementation, the main tube (132) may be formed by two or more tubes that are contiguously connected to form a single structure. The one or more rear tube(s) (133) has a front end connected to the bending portion (134). The one or more rear tube(s) (133) that extend inclinedly rearward may further comprises one or more bends in order to adapt to a layout of the vehicle (100). In an embodiment having two rear tubes, a front portion (not shown) thereof converges towards the bending portion (134) and the two rear tubes, towards the rearward direction, are spaced apart and are connected together using one or more cross-member(s) (not shown).

[00023] The vehicle (100) comprises a steering system (not shown) and a front suspension unit (140), which is part of the steering system. The steering system is rotatably movable with respect to the head tube (131). A handlebar assembly (150) is connected to the steering system for manoeuvring the vehicle (100). The front suspension unit (140) rotatably supports the front wheel (101). A power unit (120) is fixedly mounted to the main frame structure (130). In one embodiment, the main frame structure (130) includes a down tube (135), which extends obliquely downward from the head tube (131). The power unit (120) is fixedly supported by the main tube (132) and the down tube (135). The internal combustion (IC) engine (120) is mounted to a crankshaft (not shown) to rotate therewith. An electrical machine (800) (refer fig. 2) is preferably, but not limited, to an integrated starter generator (ISG). The electric machine (800) is configured to perform starting operation of the IC engine, charge a battery of the vehicle (100) during operation of the IC engine, and even assist the IC engine by providing assisting torque.

[00024] A crankshaft (not shown) enables mounting of the electrical machine (800) shown in Fig 2 on one end of the crankshaft. A crankcase (502) (refer fig. 6) is disposed adjoining to one end of the crankshaft and enclosing the electric machine (800).

[00025] The vehicle (100) includes a fuel tank (740) that is mounted to the main tube (132) and is disposed rearward to the handlebar assembly (150). Further, a seat assembly (165) is disposed rearward to the fuel tank (740). The seat assembly (165), in one implementation, in an elongated structure, in longitudinal direction F-R, and is supported by the rear tubes (133). In another implementation, as depicted in Fig. 1, the seat assembly (165) is formed by a rider-seat (160) and a pillion-seat (162), which is disposed posterior to the rider- seat (160). Further, the vehicle (100) includes a front-fender (115) mounted to the front suspension unit (140) and configured to cover at least a portion of the first wheel (101). A rear-fender (170) is suspended below the seat assembly (165). The rear-fender (170) is configured to block splashing of water or dirt from the rear wheel (102) on to passers-by and other vehicles

[00026] Fig. 2 illustrates a top view of an ISG machine (800) with respect to an embodiment of the present subject matter. In an embodiment, the ISG machine (800) is a motor in a motoring mode and a generator in a generation mode. The ISG machine (800) of the present subject matter includes a rotor (801), which is made up of a plurality of magnets that are disposed on the inner surface of the rotor (801). The rotor (801) includes a circumferential wall (801a) and a back iron plate member (501) (refer fig 6) attached to a rotating axle (503) (refer fig. 6). In an embodiment, the back iron plate member (501) (refer fig. 6) rotates along with the rotation of the rotor (801). In an embodiment, the plurality of magnets is permanent magnets.

[00027] The rotor (801) is rotatably and circumferentially mounted around the crankshaft. The stator (802) is disposed circumferentially around the crankshaft and within the rotor (801). The stator (802) is removably mounted on the crankcase (502). The control unit (201) or the ISG controller (201) is mounted integrally on the stator (802) in a space formed between the stator (802) and the crankcase (502) (refer fig. 6).

[00028] Further, the back iron plate member can be made out of any one of iron, silicon steel, which is either made as one full block of iron or silicon steel. Alternatively, the back iron plate member is made of layers of iron or silicon steel with plurality of electrical insulation layers in between. In an embodiment, the plurality of magnets of the rotor (801) can be any one of arc type magnets and flat magnets. Further, in one embodiment, the plurality of magnets are disposed adjacently to each other circumferentially, without any gap. Alternatively, the plurality of magnets can be disposed adjacently to each other circumferentially with circumferential air gap between two adjacent magnets of the plurality of magnets.

[00029] Further, the ISG machine (800) includes a stator (802) having a centrally provided stator core (818) around which a plurality of stator teeth (812) are circumferentially disposed forming a plurality of stator slots (814) there between. In an embodiment, the plurality of stator slots (814) is further fdled with plurality of winding (816). In an embodiment, the stator (802) is enclosed within the rotor (801) and radially separated by an air gap (810). In an embodiment, each tooth of the plurality of stator teeth (812) includes a stem portion. In one embodiment, the stem portion of the tooth of the plurality of stator teeth (812) is provided with equal width on both ends of the stem portion, i.e., at a first end that is towards the stator core (818) and a second end that is away from the stator core (818) thereby making the stem portion of a rectangular in shape. In an alternative embodiment, each slot of the plurality of stator slots (814) is formed to have unequal width at both ends, i.e., one width at an end that is closer to the stator core (818) and another width at an end that is away from the stator core (818), which is achieved by two adjoining tooth of the plurality of stator teeth (812) having different widths at both its ends. In another alternative embodiment, each of the tooth of the plurality of stator teeth (812) and the each of the slot of the plurality of stator slots (814) are formed in such a manner that the width of the tooth and the slot at both the ends are not equal. In one embodiment, the stem portion of the each of the tooth of the plurality of stator teeth (812) ends with a head portion facing the rotor (801), and has a width that is wider than the stem portion.

[00030] Fig. 3 illustrates a bottom perspective view of the ISG machine (800). The ISG machine (800) is controlled by an ISG controller (201). The ISG controller (201) is responsible for the motoring mode and the generating mode of the ISG machine (201). The ISG controller (201) in the present embodiment eliminates the need of mounting the ISG controller (201) on a frame of a vehicle. There is no requirement of additional mounting support. The ISG controller (201) in the present invention is in the form of a circuit board which can be located between the stator and a crankcase. The ISG controller (201) is configured in a space between the stator and the crankcase. Also, ISG controller (201) as per the present invention is configured in the form of a circuit board rather than a bulky device, thereby reducing the overall space requirement, minimising cost as well as reducing weight. This configuration eliminates the problem related to the space constraint. Also, in the present invention the ISG controller (201) is not a separate device with an additional weight. The thickness of the ISG controller (201) being configured to be low, the present invention eliminates the requirement of increasing the height of the rotating axle (503). The ISG controller (201) comprises of a circuit board (202) which further comprises the electrical components.

[00031] Fig. 4 illustrates a top view of the electric machine (800) with electrical components. It is very important for a vehicle with a compact engine assembly that the ISG machine (800) should also be compact. The ISG controller (201) is a circuit board (202) with multiple electric components mounted on the circuit board. Some of those electrical components mounted on the circuit board may get obstructed in the space created between the crankcase (502) and the stator (802) and where the circuit board (202) is disposed. To overcome this problem, the electrical components (301) such as capacitors, choke coils are securely disposed in the stator slots (814). The electrical components (301) are aligned along the radial direction of the diameter (D) of the stator (802) of the ISG machine (800) such that the height of the electrical components (301) is parallel to the diameter (D) of the stator (802). This way the electrical components (301) is configured in a narrow and compact space between the stator teeth (812) and at the same time the electrical components (301) do not cause any obstruction to any nearby ISG machine (800) components such as rotor or stator. [00032] Fig. 5 illustrates a top view and a bottom view of the ISG machine (100).

[00033] Fig. 6 illustrates a side cross-sectional view of the ISG machine (800). The stator (802) having a back iron plate member (501) faces away from a crank case (502). The stator (802) comprising stator teeth (812) is wound by a windings made up of metal such as copper. The stator teeth (822) extend in an outward direction and away from a stator core (818) refer fig 2). The rotor (801) circumferentially encloses the stator (802). The ISG controller (201) for controlling the ISG machine (800) is securely disposed between the crankcase (502) and the stator (102) of the ISG machine (101). The ISG controller (201) is mounted circumferentially to the stator (201) and adjoining the back iron plate member (501). The outer diameter of the ISG controller (201) is equal to or lesser than an outer diameter of said stator (802). The ISG controller (201) has first set of components such as MOSFETS which eliminates more heat compared to any other electrical components and therefore the MOSFET bridge, bridge isolator, buck converter, MOSFET bridge unit (heat dissipating components) are configured to be in physical contact with the stator lamination for dissipation of heat and at the same time the requirement of the additional heat sink is also eliminated. [00034] Further, the ISG controller (201) of electric machine (800) has a second set of components configured for generation phase of said electrical machine (800); wherein, said second set components (not shown?) being a converter, a converter driver and a controller to control said converter driver.

[00035] Since, the ISG controller (201) is integrally mounted with the stator (802) of the ISG machine (800), the cost involved in the wire harness routed from the ISG machine (800) to the ISG controller (201) is eliminated. Further, the routing of the wire harness as per known art required a perforation to be created in the engine crankcase of the engine assembly of the vehicle. Now, through this present invention, the ISG controller (201) is integrated with the stator (802) which thereby eliminates the perforation and prevents any oil leakage from the engine crankcase.

[00036] Fig. 7 illustrates a block diagram of the ISG machine (800) integrated with an ISG controller (201) in a circuit layout in the vehicle (100). The stator (802) with the circuit board (202) is connected to a power source such as a battery (708) through wires harness and the wire harnesses are routed along with a pulser coil (not shown). The ISG machine (800) is connected to a controller (705) and an auxiliary supply unit (704) with multiple power lines. The first line of the multiple power lines is connected to the battery (708) and the second line of the multiple power line is connected to ISG machine line (800). DC power from battery is converted into AC power using MOSFET bridge (701) and the gate terminal of the MOSFET bridge (701) is controlled by a bridge driver unit (703) which is in turn is controlled by the controller (705). The Controller (705) provides a gate signal based on the position of the rotor (801) determined by a rotor position signal. The electrical power output from ISG machine (800) is isolated from the battery (708) using a bridge isolator (709), which is controlled by the controller (705). The rectified DC output power from MOSFET bridge unit (701) is regulated using a buck converter (707) and its gate driver unit is controlled by the controller (705).

[00037] Based on an ignition switch, an electric switch and/or other input parameters, the ISG machine (800) works in motor mode. DC input from battery (708) is provided to MOSFET bridge (701) and gate input is provided by the bridge driver unit (703) which is in turn controlled by the controller (705) and the converted AC output is provided to three phase windings in the stator (802). Three-phase current in stator windings generates a rotating magnetic field which interacts with the rotor magnetic field and ISG machine (800) starts rotating to crank the engine. After successful engine start, the three -phase current supply to the ISG machine (800) winding is interrupted. ISG Machine (800) acts as generator and the three-phase output generated by the ISG Machine (800) is converted to DC power using the same inverter unit and regulated using the buck converter (707). DC link capacitors or any other components with increased axial length are placed between the stator teeth (812).

LIST OF REFERENCE SIGNS vehicle (100) rotating axle (503) main frame (130) 25 stator (802) front wheel (101) crankcase (502) rear wheel (102) ISG controller (201) head tube (131) stator core (818) main tube (132) stator slots (814) rear tube (133) 30 stator teeth (812) bending portion (134) air gap (810) handlebar assembly (150) winding (816) seat assembly (165) circuit board (202) rider-seat (160) crankcase (502) pillion-seat (162) 35 electrical components (301) front-fender (115) battery (708) front suspension unit (140) controller (705) down tube (135) auxiliary supply unit (704) rear-fender (175) MOSFET bridge (701)

ISG machine (800) 40 bridge driver unit (703) rotor (801) bridge isolator (709) circumferential wall (801a) buck converter (707)

Claims

We claim:

1. An electric machine (800) comprising: a stator (102) having a back iron plate member (501), said stator (102) comprising a plurality of stator teeth (812) being wound by a plurality of windings, said plurality of teeth (812) extending outwardly from a stator core (818); a rotor (801) circumferentially enclosing said stator (802); and a control unit (201) for controlling said electric machine (800), wherein, said control unit (201) is mounted circumferentially adjacent to said back iron plate member (501).

2. The electric machine (800) as claimed in claim 1, wherein said control unit (201) is an ISG controller; wherein, said ISG controller is integrally mounted to said stator

(802).

3. The electric machine (800) as claimed in claim 1, wherein an outer diameter of said control unit (201) is equal to or lesser than an outer diameter of said stator (802).

4. The electric machine (800) as claimed in claim 1, wherein said control unit (201) comprises a circuit board (202); wherein, said circuit board (202) comprises one or more electrical components, wherein, said one or more electrical components configured to be disposed extending axially in a stator slot (814) located between said plurality of stator teeth (812).

5. The electric machine (800) as claimed in claim 4, wherein said one or more electrical components being a capacitor (301).

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6. The electric machine (800) as claimed in claim 4, wherein said one or more electrical components being a choke coil.

7. The electric machine (800) as claimed in claim 4, wherein one or more heat dissipating components being in physical contact with a lamination of said stator (802).

8. The electric machine (800) as claimed in claim 7, wherein said one or more heat dissipating components being a MOSFET bridge, a bridge isolator, a buck converter, a MOSFET bridge.

9. The electric machine (800) as claimed in claim 2, wherein a second set of component being configured for generation phase of said electrical machine (800); wherein, said second set components being a converter, a converter driver and a controller to control said converter driver.

10. An internal combustion engine for a vehicle, said internal combustion engine comprising: a crankshaft; an electric machine (800) mounted on one end of said crankshaft; at least one crankcase (502), said at least one crankcase (502) disposed adjoining said one end of said crankshaft and enclosing said electric machine (800); said electric machine (800) comprising: a rotor (801) rotatably and circumferentially mounted around said crankshaft, a stator (802) disposed circumferentially around said crankshaft, wherein said stator (802) being mounted on said crankcase; and

2 a control unit (201) mounted on said stator in a space formed between said stator and said at least one crankcase.

11. The internal combustion engine as claimed in claim 9, wherein said stator (802) having a back iron plate member (501), and a plurality of stator teeth (812) wound by a plurality of windings, said plurality of stator teeth (812) extending outwardly from said back iron plate member (501).

12. The internal combustion engine as claimed in claim 9 or 10, wherein said control unit (201) comprises one or more heat dissipating components, said one or more heat dissipating components being configured to physically contact a lamination of said stator (802) enabling efficient heat dissipation.

13. The internal combustion engine as claimed in claim 1, wherein said control unit (202) is an ISG controller; wherein, said ISG controller (202) being disposed between said stator (802) and a crankcase (502) of said internal combustion engine.

14. A stator (102) comprising : a plurality of stator teeth (812) being wound by a plurality of windings, said plurality of stator teeth (812) extending outwardly from a stator core (818); wherein, one or more electrical components being configured to extend axially in a stator slot (814) located between said plurality of stator teeth (812).

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