A motor assembly with overrunning clutch

Abstract

A motor assembly, the motor assembly comprising an electric motor and an overrunning clutch, wherein a shaft of the overrunning clutch is adapted to engage with an external engine, the shaft being connected to an inner part of the overrunning clutch, and an outer part of the overrunning clutch is adapted to engage with a rotor shaft of the electric motor.

Description

[0001] A motor assembly with overrunning dutch

[0002] Field of the invention

[0003] The present inventive concept relates to motor assemblies, for example for use with drives for vehicles and vessels.

[0004] Background to the invention

[0005] Traditionally and for many decades, vehicles and vessels have been driven by internal combustion engines (ICEs) of various types and designs according to the requirements. More recently, environmental concerns have led to the development of alternative drive arrangements with the aim of reducing fossil fuel consumption and accompanying pollution and greenhouse gases.

[0006] Electric-only drives have been found useful in certain circumstances - for example road-going vehicles. However, electric-only drives require large energy stores which currently tend to be heavy.

[0007] Hybrid drives, where an electric motor is supplied by energy stored in a battery and / or electricity generated by an ICE, are also commonplace in road-going vehicles. However, hybrid drives are complex and space-inefficient. Hybrid drives are not suitable where space is at a premium, especially when the drive shaft space is restricted. Hybrid drives also tend to have a separate clutch.

[0008] One particular example in which space is at a premium is in vessels such as boats, where traditionally the drive is close to the load, e.g. the propeller.

[0009] The present inventive concept aims to provide a more efficient and environmentally appropriate arrangement - without requiring a comprehensive redesign of the intended vehicle or vessel. It also provides potential for retro-fitting to an existing vehicle or vessel. Summary of the invention

[0010] The present inventive concept provides a motor assembly, the motor assembly comprising an electric motor and an overrunning clutch arranged within the motor assembly, wherein a shaft of the overrunning clutch is adapted to engage with an external engine, the shaft being connected to an inner part of the overrunning clutch, and an outer part of the overrunning clutch is adapted to engage with a rotor shaft of the electric motor.

[0011] The overrunning clutch may be arranged within a hollow tubular portion of the assembly and coaxially with the rotor shaft of the electrical motor.

[0012] The overrunning clutch may be a freewheel clutch. The overrunning clutch may be a sprag clutch.

[0013] The motor assembly may engage with an external engine by way of mechanical connection to a part of the external engine, for example a flywheel. The external engine may be an internal combustion engine (ICE).

[0014] Preferably, the hollow tubular portion of the assembly forms part of the rotor shaft of the electric motor. The hollow tubular portion of the assembly may be the rotor shaft of the electric motor.

[0015] Preferably the said hollow tubular portion comprises engagement portions suitable for engagement with corresponding engagement portions of an external load. Such an external load may comprise, for example, a gearbox.

[0016] The engagement portions may comprise ridges or splines or the like. Ridges or splines are intended to provide efficient torque transfer whilst maintaining angular correspondence between the tubular portion of the motor assembly and an external load.

[0017] One or more of the engagement portions may be provided with a spline adapter, the spline adaptor having splines on at least its outside surface and an external diameter selected to match an internal diameter of a corresponding connection of an external device such as an external engine or an external load. A spline adapter provides for use of the motor assembly with a range of different external devices. Thus, the present invention can be used with external devices made by a range of different manufacturers for example. The overrunning clutch is preferably arranged so that the clutch slips when the rotor shaft of the electric motor is turning faster than the shaft in at least one rotational sense. This prevents the electric motor from turning the said external engine - which would be wasteful of energy and potentially damaging to the electric motor and the said external engine.

[0018] The overrunning clutch may comprise two sprags arranged in parallel with one another. Preferably, the two sprags are arranged adjacent one another and co-axially. When the overrunning clutch comprises two adjacent co-axial sprags the overrunning clutch can transfer a wider range of torque at a wider range of axial rotational speeds. This provides for a more adaptable and efficient arrangement while minimising the overall size (and thus space required) of the motor assembly.

[0019] The underlying inventive concept, therefore, is the provision of an overrunning clutch within a motor assembly. Compared with previously known electric motor arrangements, the present inventive concept provides a hollow region where a drive shaft would normally not provide a space in which an overrunning clutch could be located. Thus the present arrangement provides space advantages over previously known arrangements as well as efficiencies in the transfer of torque from an engine to an electric motor but not in the reverse direction.

[0020] This facilitates configurations of traditional ICE and electric power drives in vehicles and vessels, for example, which were not feasible previously. This provides opportunities for reducing fuel consumption and thus the environmental impact of power drives in situations where other forms of impact reduction are not suitable.

[0021] The present inventive concept enables a shortening of overall axial length of connection between an external engine and an external load, whilst providing sufficient transmission of torque to drive a vehicle or vessel. This is important where space is at a premium, for example in vehicles and vessels.

[0022] Especially, the present inventive concept facilitates a setup where an ICE and an electric motor can each provide torque to a load, such as a gearbox or propeller etc. in line with one another. For example, a setup can be provided in which in a first mode the ICE can drive the electric motor to generate electricity when needed and / or in turn provide torque to the load, and in a second mode the same electric motor can draw electricity to provide torque to the load. Crucially, when in this second mode, the overrunning clutch of the present inventive concept prevents the electric motor from driving the ICE - which would be inefficient, counterproductive and could result in damage to the ICE.

[0023] The present inventive concept can be used with a range of engines and vehicle / vessel configurations. The motor assembly can optionally be provided as a retro-fit device. Preferably, such a retro-fit device has dimensions adapted to fit components of an existing configuration for which it is to engage with.

[0024] The motor assembly may further comprise an electrical controller and wherein the electrical controller is connected to each of the electric motor, an external engine and a battery and wherein the electrical controller is adapted to monitor and control the output of each of the electric motor, the said external engine and the said battery.

[0025] Especially, the arrangement as described can be put into effect as part of an electrical supply system, for example for a vessel. A significant issue for vessels - such as boats - is the efficient use of scarce energy resources. Vessels typically must carry enough energy stored as fuel or battery storage for long periods. Wastage must be minimised where possible. For example, when an ICE engine is idling or running at cruising speeds, it operates inefficiently and some of its fuel consumption may be wasted. The overrunning clutch arrangement as described can harness some of that wasted ICE power and store it as electrical energy in a battery.

[0026] Furthermore in some situations the vessel may be required to operate entirely from electrical energy stored in a battery - for both drive power and to operate other electrical apparatus on the vessel.

[0027] Thus, the present inventive concept also provides an electrical supply system for a vessel, comprising a motor assembly having an electric motor and an overrunning clutch arranged within the motor assembly, wherein a shaft of the overrunning clutch is adapted to engage with an internal combustion engine (ICE), the shaft of the ICE being connected to an inner part of the overrunning clutch, and an outer part of the overrunning clutch is adapted to engage with a rotor shaft of the electric motor, the system further comprising an electrical controller and a battery and wherein the electrical controller is connected to each of the electric motor, the ICE and the battery and wherein the electrical controller is adapted to control the output of each of the electric motor, the ICE and the battery. This provides for an arrangement by which the electrical controller can determine whether and to what extent the power requirements for a vessel are met by the ICE, the electric motor, the battery or a mixture of the three as well as whether and to what extent electrical power is used to charge or discharge the battery.

[0028] The electrical supply system may further comprise a battery management system. The electrical supply system may further comprise a battery safety monitor. The electrical supply system may further comprise an inverter. The inverter may be arranged between the electric motor and the battery. Alternatively, the inverter may be connected to the electric motor on one side and to the battery management system and battery safety monitor on the other side.

[0029] The electrical supply system may further comprise a user interface. A user interface can provide for overall supervision and / or adjustment by a user.

[0030] The various elements of the electrical supply system may be connected electrically via DC or AC current as well as with data / control connections.

[0031] Some exemplary modes of operation can be described. If the ICE is being used to drive the vessel then some of the ICE's power output may be used to turn the electric motor to generate electrical energy to be stored in the battery. If it is not desirable to use the ICE to drive the vessel - for pollution and noise reasons - then electrical energy may be used from the battery to drive the electric motor.

[0032] The electrical controller may be adapted to operate the electrical supply system in one or more of the following modes: controlling the ICE to generate torque to drive the electrical motor to generate electrical power to charge the battery and / or provide electrical power to other electrical apparatus onboard the vessel; controlling the ICE and electrical motor to both generate torque; controlling the ICE to not generate torque and controlling the electrical motor to generate torque using energy stored in the battery; controlling the ICE to not generate torque and controlling the electrical motor to not generate torque and using energy stored in the battery to provide electrical power to other electrical apparatus onboard the vessel.

[0033] The electrical supply system may thus be used to reduce overall fuel demand - because energy from wasted combustion energy can be stored in the battery for use later. This would generally reduce fuel consumption and resulting carbon emissions and pollution. Furthermore, fuel consumption and pollution can be reduced in situations where the noise and pollution may have a particularly negative impact - such as in harbour. Thus the electrical supply system of the present invention can provide synergistic advantages.

[0034] Detailed description of exemplary embodiments

[0035] Exemplary embodiments of the present inventive concept will now be described in further detail, with reference to the accompanying drawings.

[0036] Figure 1 shows an exploded view of an exemplary embodiment of the assembly of the present inventive concept.

[0037] Figure 2 shows the same assembly as shown in Figure 1, in its assembled form.

[0038] Figure 3 shows the same assembly as shown in Figures 1 and 2, in cross section perpendicular to the axis of the assembly.

[0039] Figure 4 shows the same assembly as shown in Figures 1 to 3, in cross section along the axis of the assembly.

[0040] Figure 5 shows how an exemplary embodiment of a motor assembly of the present inventive concept could be arranged within a wider system.

[0041] Figure 6 shows an extract of a view of an exemplary embodiment of the assembly, having two sprag clutches.

[0042] Figure 7 shows diagrammatically electrical connections between an exemplary electrical controller for use as described above.

[0043] Figure 8 shows diagrammatically electrical and data connections between an exemplary electrical controller for use as described above, as part of an exemplary electrical supply system.

[0044] In Figure 1, the assembly 10 has an electric motor (only key rotor elements of which are shown) which has components including a rotor 14, magnets 16, tube nuts 18, a retaining ring 20, and a target ring 22. The electric motor has a rotor shaft 24 which has a hollow tubular portion 26 formed within it. The hollow tubular portion 26 may be provided with a splined region 28 at at least one end thereof, for engagement with a part of an external load, such as a shaft thereof. In this exemplary embodiment, the overrunning clutch is a sprag clutch 30. The hollow tubular portion 26 also accommodates and engages an outer freewheel clutch unit 32 of a sprag clutch 30. An inner part 34 of the sprag clutch 30 is joined to a sprag shaft 36 which can engage with an external engine.

[0045] The assembly 10 also has a seal ring 38, lip seals 40, 42, snap rings 44, 46 and socket head screws 48.

[0046] The outer part 32 of the sprag clutch 30 is connected to the hollow tubular portion 36 of the electric motor by a press fit connection. The inner part 34 of the sprag clutch 30 is connected to the sprag shaft 36 by a press fit connection. Using a press fit to connect the two parts of the sprag clutch 30 to the respective hollow tubular portion 36 and sprag shaft 36 provides for substantially equal pressure on the sprag clutch 30 from both sides thereof. Alternatively, pawls and ball races could be fitted to run on hardened faces of the respective shafts.

[0047] Elements of the electric motor can be held together in place by tube nuts 18 and socket head screws 48 passing through the other elements and being attached together. Such an attachment can be further improved by providing an adhesive.

[0048] The key components of the assembly 10 are arranged co-axially along an axis of the assembly X. As can be seen in Figure 1, the electric motor, the sprag clutch 30, the rotor shaft 24 and the sprag shaft 36 are co-axial along the axis X of the assembly 10.

[0049] The sprag clutch 30 is configured so that, in use, when the sprag shaft 36 (and thus the inner part 34 of the sprag clutch 30) is rotating faster than the outer part 34 of the sprag clutch 30 in the rotational sense of the configured drive then the sprag engages, transferring torque from the sprag shaft 36 to the inner part 34 of the sprag clutch, and in turn to the rotor shaft 24 of the electric motor. When the rotor shaft 24 is rotating faster than the sprag shaft 36, then the sprag clutch 30 slips so that torque transference is significantly reduced. The result is that the electric motor does not tend to transfer torque to the sprag shaft 36 and onwards to an external engine. In Figure 2, the same assembly 10 as shown in Figure 1, and described above, is shown in its assembled form. Certain components are not labelled, to aid clarity. The electric motor (again only key rotor elements of which are shown) has the sprag clutch 30 arranged within it, so that only certain parts of the sprag clutch 30 are seen in Figure 2 - for example where they extend from the electric motor. On one side of the electric motor, the splined region 28 of the hollow tubular portion 26 extends from the sprag clutch 30 and electric motor for engagement with an external load. On the other side, the sprag shaft 36 extends from the sprag clutch 30 for engagement with an external engine.

[0050] The key components of the assembly 10 are arranged co-axially along an axis of the assembly X. As can be seen in Figure 2, the electric motor, the sprag clutch 30, the tubular portion 26 and the sprag shaft 36 are co-axial along the axis X of the assembly 10.

[0051] In use, the sprag shaft 36 can turn the sprag clutch 30 and thus the electric motor when the sprag shaft 36 is rotating faster than the electric motor in the configured rotational sense. When the electric motor is rotating faster than the sprag shaft 36, the sprag clutch 30 slips so that torque transference is significantly reduced.

[0052] In Figure 3, a cross section view of the same assembly 10 as shown in Figures 1 and 2 is shown. Certain components are not labelled, to aid clarity. The electric motor (again only key rotor elements of which are shown) has the sprag clutch 30 arranged within it, with the outer part 32 in connection with the hollow tubular portion 26 of the motor. The inner part 34 of the sprag clutch 30 is joined to the sprag shaft 36. The sprag clutch 30 is arranged at one side of the hollow tubular portion 26, so that the sprag shaft 36 extends from one end thereof. At the other side of hollow tubular portion 26 is the splined region 28 which is for engagement with an external load. The electric motor, the sprag clutch 30, the tubular portion 26 and the sprag shaft 36 are co-axial along the axis X of the assembly 10.

[0053] As can be seen especially in Figures 2 and 3, the assembly 10 provides a compact arrangement so that axial space requirements are reduced compared with previous arrangements. For example, with reference to Figure 3, the length of the embodiment shown, i.e. the length of assembly 10 between the opening of the hollow tubular portion 26 on the left-hand side of the drawing and the end of the sprag shaft 36 on the right-hand side of the drawing is approx. 160 mm. The overall diameter of the embodiment, whose largest dimension is the outer surface of the rotor is approx. 320 mm. In Figure 4, an alternative cross section view of the same assembly 10 is shown, along the axis X of the assembly. Certain components are not labelled, to aid clarity. The electric motor, the sprag clutch 30, the tubular portion 26 and the sprag shaft 36 are co-axial along the axis X of the assembly 10.

[0054] In Figure 5, an exemplary assembly 10 is shown within a wider system. The system has an internal combustion engine (ICE) E and a load L which includes a gearbox and other parts. Only certain components of the assembly 10 are labelled, to aid clarity. The sprag shaft 36 is connected to a flywheel F of the engine E to transfer torque from the engine E to the sprag clutch 30. On the other side of the assembly 10, the load L can engage with the hollow tubular portion 26 by way of a gearbox shaft S.

[0055] The sprag clutch 30 is configured so that, in use, when the sprag shaft 36 (and thus the inner part 34 of the sprag clutch 30) is rotating faster than the outer part 34 of the sprag clutch 30 in the rotational sense of the configured drive - when the engine E is providing torque - then the sprag engages, transferring torque from the sprag shaft 36 to the inner part 34 of the sprag clutch, and in turn to the rotor shaft 24 of the electric motor. When the rotor shaft 24 is rotating faster than the sprag shaft 36, then the sprag clutch 30 slips so that torque transference is significantly reduced. The result is that the electric motor does not tend to transfer torque to the sprag shaft 36 and onwards to the engine E. Thus, the load L can be driven by the engine E or the electric motor but torque is generally not transferred from the electric motor to the engine E.

[0056] Figure 6 shows elements of another exemplary embodiment of the assembly as described. The exemplary embodiment of the assembly 10' with certain elements of an electric motor shown, such as a rotor 14'. The electric motor has a rotor shaft 24' which has a hollow tubular portion 26' formed within it. The hollow tubular portion 26' has a splined region 28' for engagement with another part such as a propeller. The hollow tubular portion 26' also accommodates and engages an overrunning clutch. In this embodiment the overrunning clutch has two sprag clutches 30', 31' arranged in parallel with one another arranged adjacent one another and coaxially. Thus an outer part of the sprag clutches 30', 31' engage with the hollow tubular portion 26'. An inner part of the sprag clutches 30', 31' is joined to a sprag shaft 36' which can engage with an external engine. The sprag shaft 36' has splines on its outside surface. The splined outside surface can engage with a corresponding connection of an external device or a spline adapter.

[0057] The key components of the assembly 10' are arranged co-axially along an axis of the assembly X'. As can be seen in Figure 6, the electric motor, the sprag clutches 30', 31 ’, the rotor 24' and the sprag shaft 36' are co-axial along the axis X' of the assembly 10'.

[0058] The sprag clutches 30', 31 ’ are configured so that, in use, when the sprag shaft 36' (and thus the inner part 34' of the sprag clutches 30', 3T) is rotating faster than the outer part of the sprag clutches 30', 31 ’ in the rotational sense of the configured drive then the sprags engage, transferring torque from the sprag shaft 36' to the inner part 34' of the sprag clutches, and in turn to the rotor 24' of the electric motor. When the rotor 24' is rotating faster than the sprag shaft 36', then the sprag clutches 30', 31' slip so that torque transference is significantly reduced. The result is that the electric motor does not tend to transfer torque to the sprag shaft 36' and onwards to an external engine.

[0059] Figure 7 shows diagrammatically how an electrical controller as described above may be connected electrically to other elements. In general the electrical controller is connected to each of the electric motor, an external engine such as an ICE and a battery. The electrical controller is adapted to monitor and control the output of each of the electric motor, the said external engine and the said battery as described above. Furthermore, the electrical controller can be put into effect as part of an electrical supply system, for example for a vessel, as described above. The ICE and electric motor as shown in Figure 7 form part of a motor assembly as described herein.

[0060] Figure 8 shows diagrammatically how an electrical controller as described above may be connected electrically and data connected to other elements to form an exemplary electrical supply system. Some of the electrical connections are via direct current (DC) and others are via alternating current (AC). Some of the data connections also provide control so that one element can send instructions / control signals to another element. In Figure 8 data connections are shown as dashed arrows with an arrow in one direction only to indicate the direction of data flow; data and control connections are shown as double-headed arrows with a solid line to indicate that data or control signals can flow in either direction; AC electrical power connections are shown as dashed lines with no arrows; DC electrical power connections are shown as solid lines with no arrows. Figure 8 includes a legend accordingly.

[0061] An electrical controller 100 is data connected to a battery management system 102, with the data flowing from the battery management system 102 to the electrical controller 100. In turn the battery management system 102 is DC electrically connected to a load 104 such as electrical apparatus on a vessel and an inverter 104 (which is AC electrically connected to an electric motor which is part of a motor assembly 10 of the present disclosure). The battery management system 102 and inverter 104 are DC electrically connected to a battery safety monitor 106. The battery safety monitor 106 is in turn DC electrically connected to a battery 108. The electrical controller 100 is adapted to monitor and control the output of each of the electric motor and inverter 104, the said external engine and the battery 108 as described above, via the battery management system 102 and battery safety monitor 106. The electrical controller 100 is in data connection with the battery management system 102 and adapted to receive data therefrom. The electrical controller 100 also receives data from the ICE and electric motor. The electrical controller 100 can send and receive data and control signals to and from the battery safety monitor 106 and also can send and receive data and control signals to and from the inverter 104. Thus the electrical supply system can monitor and control the flow of electrical energy around the supply system according to need and conditions as described. A user interface 110 is in two-way data control connection with the electrical controller 100; thus a user can supervise and / or make adjustments to the operation of the electrical supply system.

Claims

Claims1. A motor assembly, the motor assembly comprising an electric motor and an overrunning clutch arranged within the motor assembly, wherein a shaft of the overrunning clutch is adapted to engage with an external engine, the shaft being connected to an inner part of the overrunning clutch, and an outer part of the overrunning clutch is adapted to engage with a rotor shaft of the electric motor.

2. A motor assembly according to claim 1, wherein the overrunning clutch is arranged within a hollow tubular portion of the assembly and coaxially with the rotor shaft of the electrical motor.

3. A motor assembly according to claim 2, wherein the hollow tubular portion of the assembly forms part of the rotor shaft of the electric motor.

4. A motor assembly according to claim 2 or claim 3, wherein the said hollow tubular portion comprises engagement portions suitable for engagement with corresponding engagement portions of an external load.

5. A motor assembly according to claim 4, wherein the engagement portions comprise ridges or splines.

6. A motor assembly according to claim 4 or 5, wherein one or more of the engagement portions is provided with a spline adapter.

7. A motor assembly according to any preceding claim, wherein the overrunning clutch is arranged so that the clutch slips when the rotor shaft of the electric motor is turning faster than the shaft in at least one rotational sense.

8. A motor assembly according to any preceding claim, wherein the overrunning clutch is a freewheel clutch.

9. A motor assembly according to claim 6, wherein the overrunning clutch is a sprag clutch.

10. A motor assembly according to claim 9, wherein the overrunning clutch comprises two sprags arranged in parallel with one another.

11. A motor assembly according to claim 10, wherein the two sprags are arranged adjacent one another and co-axially.

12. A motor assembly according to any preceding claim, further comprising an electrical controller and wherein the electrical controller is connected to each of the electric motor, an external engine and a battery and wherein the electrical controller is adapted to monitor and control the output of each of the electric motor, the said external engine and the said battery.

13. A retro-fit device, comprising a motor assembly according to any preceding claim.

14. An electrical supply system for a vessel, comprising a motor assembly having an electric motor and an overrunning clutch arranged within the motor assembly, wherein a shaft of the overrunning clutch is adapted to engage with an internal combustion engine (ICE), the shaft of the ICE being connected to an inner part of the overrunning clutch, and an outer part of the overrunning clutch is adapted to engage with a rotor shaft of the electric motor, the system further comprising an electrical controller and a battery and wherein the electrical controller is connected to each of the electric motor, the ICE and the battery and wherein the electrical controller is adapted to control the output of each of the electric motor, the ICE and the battery.

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