Transfer case for hybrid conversion of a truck

Abstract

A transfer case for use in hybrid conversion of a truck, the transfer case comprising an input gear, an output gear, at least one electric motor gear, wherein the input gear is configured to connect via an input shaft to an internal combustion engine of the truck, wherein the output gear is configured to connect via an output shaft to a transmission of the truck, wherein the at least one electric motor gear is configured to connect to an electric motor, and wherein the output gear and the at least one electric motor gear are arranged to mesh with the input gear.

Description

TitleTRANSFER CASE FOR HYBRID CONVERSION OF A TRUCKField of the Invention

[0001] The invention relates to a Transfer Case for hybrid conversion of a truck.Background

[0002] The following discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge as at the priority date of the application.

[0003] Large trucks are used on mine sites for transport of ore, for example. Such trucks are also referred to as haul trucks, or dump trucks.

[0004] The shift in the industry toward electric power is desirable for a variety of reasons, including environmental, offering a reduction in greenhouse gasses.

[0005] Battery electric, and hybrid, trucks are in development and are beginning to appear on the market.

[0006] Trucks are particularly expensive and have a long service life of many decades. Replacement of a fleet of trucks is therefore a significant capital cost. Replacement of trucks well before the end of their service life is also bringing forward that capital cost undesirably.

[0007] There is a need to offer a solution to convert existing trucks to reduce the environmental impact, while avoiding the cost of replacement of the truck.

[0008] Such trucks have not been designed with conversion in mind, and the arrangement of the existing hardware restricts the available space and results instrict limitations with existing hardware interface, that prove problematic to integrate new hardware.

[0009] It is an aim of the invention to provide a system with which to convert a truck to hybrid power.

[0010] Throughout the specification unless the context requires otherwise, the word "motor" or variations such as "motors", will be understood to imply the inclusion of motor generator or motor generators, it is commonplace and known that electric motors can generally be operated in two modes, one to convert electricity to mechanical movement (motor), and one to generate electricity from mechanical movement (generator).

[0011] Throughout the specification unless the context requires otherwise, the word "battery" or variations such as "batteries", will be understood to imply the inclusion of other suitable energy storage means as would be understood by the skilled addressee to be suitable alternatives.

[0012] Throughout the specification unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0013] Throughout the specification unless the context requires otherwise, the word "include" or variations such as "includes" or "including", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.Summary of Invention

[0014] According to an embodiment of the invention, there is provided a transfer case for use in hybrid conversion of a truck, the transfer case comprising an input gear, an output gear, at least one electric motor gear, wherein the input gear is configured to connect via an input shaft to an internal combustion engine of the truck, wherein the output gear is configured to connect via an output shaft to a transmission of the truck, wherein the at least one electric motor gear is configured to connect toan electric motor, and wherein the output gear and the at least one electric motor gear are arranged to mesh with the input gear.

[0015] According to another embodiment of the invention, there is provided a system for hybrid conversion of a truck, the truck comprising an internal combustion engine, a torque converter, an original transfer case and a transmission, the system comprising a replacement transfer case, at least one electric motor, a motor controller, a battery and a hybrid system control unit.

[0016] According to another embodiment of the invention, there is provided a hybrid truck comprising an internal combustion engine, a torque converter, a transfer case, at least one electric motor, a motor controller, a battery and a hybrid system control unit, wherein the transfer case is arranged to selectively transfer power from either or both of the torque converter and the at least one electric motor to the transmission.

[0017] According to another embodiment of the invention, there is provided a method of converting a truck from an internal combustion powered drive train to a hybrid powered drive train, the truck comprising an internal combustion engine, a torque converter, an original transfer case and a transmission, wherein the original transfer case is arranged to transfer power from the torque converter to the transmission, the method comprising; removing the original transfer case, installing a replacement transfer case, wherein the replacement transfer case comprises at least one more gear than the original transfer case, and wherein the replacement transfer case is arranged to selectively transfer power from either or both of the torque converter or the at least one electric motor to the transmission.

[0018] In an embodiment, the method further involves installing at least one electric motor, a motor controller, a battery and a hybrid system control unit.

[0019] According to another embodiment of the invention, there is provided a kit of parts for converting a truck to hybrid power, the kit of parts comprising a replacement transfer case, at least one electric motor, a motor controller, a battery and a hybrid system control unit, wherein the transfer case is configured to engage with the at least one electric motor, a torque converter of the truck and a transmission of the truck.

[0020] In an embodiment, the truck is a haul truck or dump truck.

[0021] In an embodiment, the truck is an off-highway haul truck.

[0022] In an embodiment, the truck is a Caterpillar haul truck.

[0023] In an embodiment, the truck is Caterpillar 785 model dump truck.

[0024] In an embodiment, the original transfer case comprises an input gear and an output gear.

[0025] Preferably, a distance that the input shaft and the output shaft are offset by is the same as the distance before the conversion.

[0026] Preferably, the input gear is arranged on an input shaft and the output gear is arranged on an output shaft, wherein the input shaft is offset from the output shaft.

[0027] Preferably, the input gear is connected via the input gear shaft to an internal combustion engine. Preferably the internal combustion engine is a diesel engine.

[0028] Preferably the input gear shaft is connected to a torque converter, and the torque converter is connected to the internal combustion engine.

[0029] Preferably, the output shaft is an input shaft of the transmission.

[0030] In an embodiment, the at least one electric motor is coupled to at least one electric motor gear, wherein the electric motor gear is arranged to engage with the input gear.

[0031] In an embodiment, the at least one electric motor is two electric motors, being a first electric motor and a second electric motor.

[0032] Preferably, the first electric motor is coupled to a first electric motor gear, and the second electric motor is coupled to a second electric motor gear, wherein the first electric motor gear and the second electric motor gear are arranged to engage with the input gear.

[0033] In an embodiment, the at least one electric motor gear is a first electric motor gear and a second electric motor gear, wherein the first electric motor gear isconfigured to couple to a first electric motor, and the second electric motor gear is configured to couple to a second electric motor.

[0034] In an embodiment, the at least one electric motor gear is arranged to engage with the input gear via a spacer gear.

[0035] In an embodiment, the first electric motor gear is arranged to engage with the input gear via a first spacer gear.

[0036] In an embodiment, the second electric motor gear is arranged to engage with the input gear via a second spacer gear.

[0037] In an embodiment, the control unit is arranged to interface with the motor controller.

[0038] In an embodiment, the motor controller is configured to control the speed of the at least one electric motor.

[0039] Preferably, the motor controller is configured to match the speeds of the first electric motor and the second electric motor.

[0040] In an embodiment, the control unit is arranged to interface with the internal combustion engine.

[0041] In an embodiment, the control unit is configured to control the speed of the internal combustion engine.

[0042] In an embodiment, the control unit is arranged to interface with the torque converter.

[0043] In an embodiment, the control unit is configured to adjust the amount of torque transmitted from the internal combustion engine to the input shaft of the transfer case.

[0044] In an embodiment, the control unit is configured to selectively engage a mechanical clutch of the torque converter.

[0045] In an embodiment, the control unit is arranged to interface with the transmission.

[0046] In an embodiment, the control unit is arranged to select a suitable gear ratio of the transmission to optimise regenerative energy capture.

[0047] Unless the contrary is apparent, embodiments of the above-described principal aspects, may comprise or incorporate, either individually or in combination, any of the subsequently described features.Brief Description of Drawings

[0048] In order to provide a better understanding, embodiments of the present invention will be described, by way of example only, with reference to the accompanying drawings, in which:Figure 1 is a schematic diagram of a conventional unmodified internal combustion engine powered drive train.Figure 2 is a schematic diagram of a converted drive train according to an embodiment of the invention.Figure 3 is an elevation view of a replacement transfer case as used in an embodiment of the invention.Figure 4 is a front view of a replacement transfer case as used in an embodiment of the invention.Figure 5 is an isometric view of a replacement transfer case as used in an embodiment of the invention.Figure 6 is an isometric view of a replacement transfer case as used in an embodiment of the invention, with part of the housing omitted so that the internal arrangement of gears is visible.Figure 7 is a view of a truck with the transfer case and electric motors shown in position.Description of Embodiments

[0049] Referring to Figure 1, there is shown a conventional drive train of an internal combustion engine powered haul truck 500, for example of a Caterpillar 785 haultruck 500. The arrangement depicted is common across a number of other similar haul trucks 500, and the invention is not limited to only Caterpillar 785 models. Truck 500

[0050] The truck 500 may be a off-highway haul truck or dump truck. The system 10 of the invention has been designed with the Caterpillar model 785 in mind, although the same inventive concept can be applied to other such trucks 500.

[0051] The function of an off-highway haul truck is to transport large masses and volumes of product, for example ore, around mine sites. Mine sites may have steep inclines and the trucks 500 are required to transport significant loads.

[0052] Off-highway haul trucks 500 intended for such use may be too large to travel on roads in the conventional manner, and are transported to site either in parts, or on special wide transports with support vehicles.

[0053] As an example, the Caterpillar 785 haul truck 500 measures over 12m long, over 5.5m high, over 6m wide and has a wheel base of over 5m.

[0054] It has a maximum rated payload of 141t, and a maximum speed of around 55 km / h.

[0055] The drive train 1000 of a truck 500 of the type intended to be converted according to the invention, comprises an internal combustion engine 1200 connected to a torque converter 1300. The torque converter 1300 is connected to an input shaft 1130 of a transfer case 1100, and an output shaft 1140 of the transfer case 1100 is connected to a transmission 1400. The transmission 1400 then drives the wheels 1600 of the truck 500, via a differential 1500.

[0056] The drive train 1000 allows the rotational energy of the engine 1200 to be converted to a suitable output rotational speed to cause the haul truck 500 to commence moving from a stationary position. As the haul truck 500 accelerates the transmission 1400 will automatically disengage one set of gears and engage another to allow the engine 1200 to stay within a limited rotational speed and continue to increase the wheel 1600 speed until the optimum travel speed is achieved.

[0057] The transfer case 1100 in the exemplary embodiment comprises an input shaft 1130 that is offset from an output shaft 1140. The offset shafts allow for anassociated input gear 1132 and output gear 1142 to mesh with one another, whilst the overall length of the drive train 1000 is minimised.

[0058] The transfer case 1100 is arranged in the drive train 1000 between the torque converter 1300 and the transmission 1400.

[0059] The input shaft 1130 of the transfer case 1100 is the output shaft 1310 of the torque converter 1300. The torque converter 1300 is connected to the internal combustion engine 1200.

[0060] Typically, the internal combustion engine 1200 will be coupled to a torque converter 1300 and the output of the torque converter 1300 will drive the transmission 1400 via the transfer case 1100. A torque converter 1300 in its simplest form is a fluid coupling whereby two turbine fans are free to rotate on a common axis independent of each other. The turbines exist in a sealed container filled with a fluid, typically a viscus oil.

[0061] The internal combustion engine 1200 is connected to one turbine. The transmission input (or transfer case 1100 input) is connected to the second turbine. The viscous fluid will be deflected off the first turbine blades and onto the blades of the second turbine. The force exerted by the viscous fluid against the second turbine will cause it to rotate thus allowing the rotational energy of the internal combustion engine 1200 to be transmitted to the transmission 1400. A unique feature of a torque converter 1300 as opposed to a simple fluid coupling is the manner in which it can multiply the input torque to provide a much greater output torque which causes the stationary mass of the vehicle to commence moving.

[0062] The torque converter 1300 has an additional feature of a mechanical clutch 1310 which engages when the rotating speed of the driven turbine matches that of the input turbine and internal combustion engine 1200. This is referred to as "lock up clutch". When the truck 500 begins moving from a stationary position the turbines are free to rotate and the clutch 1310 will only move to the lock up position once the turbine speeds are matched.

[0063] This method provides dampening of shock loads that would otherwise be transmitted along the transmission 1400 gears and potentially lead to mechanicalfailures as well as offering a greater energy efficiency with no losses once the lock up clutch 1310 is engaged.

[0064] The truck 500 of the type intended to be converted according to the invention is a large truck, such as a haul truck or dump truck, an off-highway haul truck. Examples of trucks 500 to which the invention is intended to be applied are Caterpillar haul trucks, such as a Caterpillar 785 model, or 789 model.

[0065] The drive train 1000 of a truck 500 of the type intended to be converted according to the invention, has a limited available space in which to incorporate a means of hybridisation, for example electric motors.

[0066] An alternative conventional arrangement, not shown, is a diesel-electric haul truck, which uses a diesel powered internal combustion engine to drive a generator to produce electrical energy. The electrical energy is used to power electric motors connected to the drive wheels to provide tractive power.

[0067] A diesel-electric truck will consume diesel to provide tractive power to drive along flat ground or to travel up an incline. In many mining operations where dieselelectric trucks are in operation the truck will be required to travel up a gradient from the bottom of a quarry where ore is being excavated, up to the surface and along typically flat roads to a point where the ore is unloaded. The return trip completes a cycle and the truck is loaded once more with excavated ore.

[0068] The opportunity to reduce diesel consumption occurs when the unladen truck is driving down the incline. Over this change of elevation there is an energy change from potential energy to kinetic energy. Travelling downhill causes the vehicle to accelerate as the kinetic energy increases. As a speed increase is undesirable and can lead to catastrophic safety problems the vehicle must control the increase in kinetic energy by braking. In the case of a diesel-electric haul truck the "braking" is done by momentarily converting the electric motors into generators and unloading the electric energy they produce into large electrical resistors. In doing so the electric current produced is turned into heat and lost to the atmosphere.

[0069] In this way it is evident that a diesel-electric haul truck converts useful electrical energy into heat for the purpose of slowing down to maintain a constant speed down an incline.

[0070] A mechanical drive off highway haul truck 500 must control vehicle speed when travelling down an incline in the same way a diesel-electric off highway haul truck does. Kinetic energy is lost to heat by applying the brakes and / or using the rotation of the drive train in a reversed-torque fashion (with the drivetrain trying to accelerate the engine 1200) to force the engine 1200 to rotate faster. This also results in a loss of energy to heat.

[0071] Referring to Figure 2, there is shown a truck 500 converted to hybrid drive using a system 10 according to an embodiment of the invention, the truck 500 comprising an internal combustion engine 1200, a torque converter 1300, a replacement transfer case 100, at least one electric motor 20, a motor controller 30, a battery 40 and a hybrid system control unit 50, wherein the transfer case 100 is configured to selectively transfer power from either or both of the torque converter 1300 or the at least one electric motor 20 to the transmission 1400.

[0072] According to an embodiment of the invention, the truck 500 retains the original internal combustion engine 1200, torque converter 1300 and transmission 1400.

[0073] The original transfer case 1100 is replaced, the input shaft 1130, input gear 1132, and the output shaft 1140 and output gear 1142 may be retained. Alternatively, they may be replaced with a new input shaft 130, input gear 132, output shaft 140 and output gear 142.

[0074] The shafts and / or gears may be retained to save costs, in cases where the gear ratios for example are not required to be altered, and the wear of the gears does not indicate that they should be changed, the gears may be retained and encased in the replacement transfer case housing 110 as part of the replacement transfer case 100.

[0075] Further reference to the integers of the input shaft (130 or 1130), input gear (132 or 1132), output shaft (140 or 1140) and output gear (142 or 1142) should be taken to mean that either of the existing or replacement gears or shafts are considered to be suitable alternatives and within the scope of the invention.

[0076] In some circumstances, the gear ratios may be altered, for example to better integrate with the motor(s) 20 of the system 10.

[0077] To perform the conversion, the original transfer case 1100 is removed, and replaced with a replacement transfer case 100, the replacement transfer case 100 comprises at least one electric motor gear 120, which is configured to engage with at least one electric motor 20. The conversion also requires the addition of a motor controller 30, a battery 40 and a hybrid system control unit 50.

[0078] The control unit 50 may be arranged to interface with the motor controller 30. The motor controller 30 may be configured to control the speed of the at least one electric motor 20. The motor controller 30 may be configured to adjust and / or match the speeds of the first electric motor 22 and the second electric motor 24.

[0079] The control unit 50 may be arranged to interface with the internal combustion engine 1200. The control unit 50 configured to control the speed of the internal combustion engine 1200.

[0080] The control unit 50 may be arranged to interface with the torque converter 1300.

[0081] The control unit 50 may be configured to adjust the amount of torque transmitted from the internal combustion engine 1200 to the input shaft 130 of the transfer case 100. Adjustment of the amount of torque is achieved by control of the torque converter 1300. The control unit 50 may be further configured to selectively engage a mechanical clutch of the torque converter 1300.

[0082] The concept of inserting an electric motor 20 into the drive train in order to capture the excess energy offers an opportunity to reduce diesel consumption by first capturing energy when travelling down an incline and storing it in the battery 40 and then reusing the captured energy to assist in driving the mechanical power train 1000 when travelling back up the incline. The reduction in diesel consumption is directly proportional to the energy captured and reused. Thus, a reduction in greenhouse gas emissions can be demonstrated.

[0083] Other benefits include reduced wear to braking components, extended engine life due to the lower duty cycle the extra electrical energy enables.

[0084] Each manufacturer of mechanical drive train off highway haul trucks 500 has their own unique approach to the drive train design. Typically, the dimensions of a mechanical drive trains 1000 for off highway haul trucks 500 dictate the overall lengthof the vehicle. The combined length of an engine 1200, torque convertor 1300, drive shaft, transmission 1400 and differential 1500 leaves little opportunity to simply install an electric motor 20 in series within the drive train 1000.

[0085] In the case of the exemplary off highway haul truck 500 the transmission 1400 has an input shaft 1130 axis that is offset from the axis of the torque convertor 1300. The offset comprises two intermeshed helical gears. One sitting above the other. The input gear 1132 is connected to the output of the torque convertor 1300 via a drive shaft. The output gear 1142 is connected to the input of the transmission 1400. The two gears exist within a housing referred to as a transfer case 1100. The purpose of the transfer case 1100 is to transfer input energy to the transmission 1400 via the two intermeshed gears that exist on separate, parallel axis.

[0086] As shown in Figures 3 to 6, the invention enables at least one electric motor 20 to be added to the drive train 1000 by using an alternative design of replacement transfer case 100.

[0087] The electric motor gear 120 may be arranged to interface with the input gear 132, and the output gear 142 may also be arranged to interface with the input gear 132 so that power transfer is enabled from either or both of the at least one electric motor 20 or the torque converter 1300 to the transmission 1400.

[0088] The transfer case 100 and its associated gears are designed to withstand the significantly higher torque loads encountered in off-highway haul trucks 500 compared to passenger vehicles. The input gear 132, output gear 142, and electric motor gear 120 are dimensioned and manufactured from materials suitable for transmitting the combined torque of the internal combustion engine 1200 and the at least one electric motor 20, which may be in excess of several thousand newton-metres. The housing 110 of the transfer case 100 is designed to support the bearings and shafts under these high torque loads while maintaining precise gear alignment. The structural requirements of the transfer case 100 for off-highway haul truck applications are fundamentally different from those of gear train assemblies designed for passenger vehicle hybrid systems, which typically handle torque loads that are an order of magnitude lower. The at least one electric motor 20 may be configured to displace 100% of the power provided by the diesel engine.

[0089] The replacement transfer case 100 is configured such that the distance between the axis of the input shaft 130 and the axis of the output shaft 140 is the same as the corresponding distance in the original transfer case 1100. By maintaining the same shaft offset distance, the replacement transfer case 100 can be installed without requiring any modification to the alignment of the torque converter 1300 or the transmission 1400. This is particularly important in the context of off-highway haul trucks 500, where the drivetrain components are subject to very high loads and precise alignment is critical to avoid premature wear and mechanical failure. The replacement transfer case housing 110 is dimensioned to accommodate the at least one electric motor gear 120 and associated electric motor 20 while preserving the original shaft offset geometry.

[0090] The transfer case 100 provides a solution to the space constraints inherent in off-highway haul truck drivetrains 1000. Rather than adding length to the drivetrain 1000 by placing an electric motor in series with the driveshaft, the transfer case 100 accommodates the electric motor 20 in a direction perpendicular or at an angle to the drivetrain axis, by means of the electric motor gear 120 meshing with the input gear 132. The electric motor 20 is thereby positioned alongside the transfer case 100 rather than in-line with the drivetrain 1000, avoiding any increase in the overall length of the drivetrain 1000. This is advantageous because the combined length of the engine 1200, torque converter 1300, drive shaft, transmission 1400 and differential 1500 leaves little opportunity to install an electric motor 20 in series within the drivetrain 1000 without significant structural modification to the truck 500.

[0091] The at least one electric motor 20 may be two electric motors, being a first electric motor 22 and a second electric motor 24.

[0092] The first electric motor 22 is coupled to a first electric motor gear 122, and the second electric motor 24 is coupled to a second electric motor gear 124, wherein the first electric motor gear 122 and the second electric motor gear 124 are arranged to engage with the input gear 132.

[0093] Spacer gears may be required, to provide greater distance between the input gear 132 and the motor gear 120, or gears 122,124.

[0094] The at least one electric motor gear 120 may be arranged to engage with the input gear 132 via a spacer gear.

[0095] The first electric motor gear 122 may be arranged to engage with the input gear 132 via a first spacer gear 126, and the second electric motor gear 124 may be arranged to engage with the input gear 132 via a second spacer gear 128.

[0096] The use of two electric motors 22, 24, each coupled to a respective electric motor gear 122, 124, provides several technical advantages in the context of off-highway haul truck conversion.

[0097] First, two smaller electric motors 22, 24 can be more readily accommodated within the available space envelope around the transfer case 100 than a single larger motor of equivalent total power. Second, the use of two electric motors 22, 24 provides redundancy, such that the truck 500 can continue to operate in a hybrid mode even if one of the electric motors 22, 24 fails. This is particularly important in remote mining operations where immediate repair may not be possible. Third, the two electric motors 22, 24 can be independently controlled by the motor controller 30 to balance the load on the input gear 132, reducing asymmetric gear loading and extending the service life of the transfer case gears. Fourth, the two electric motors 22,24 results in two points of engagement with the input gear 132, rather than a single point of engagement. The two points of engagement provides smoother interaction, resulting in increased operability and reduced wear.

[0098] The invention may be provided as a kit of parts for conversion of a truck 500 to hybrid power, the kit of parts comprising a replacement transfer case 100, at least one electric motor 20, a motor controller 30, a battery 40 and a hybrid system control unit 50, wherein the transfer case 100 is configured to engage with the at least one electric motor 20, a torque converter 1300 of the truck 500 and a transmission 1400 of the truck 500.

[0099] The kit of parts may comprise a first electric motor 22 and a second electric motor 24, and the transfer case 100 may comprise a first electric motor gear 122 and a second electric motor gear 124.

[0100] The kit of parts may further comprise a first spacer gear 126 and a second spacer gear 128.

[0101] The invention may be provided as a transfer case 100 for use in hybrid conversion of a truck 500, the transfer case 100 comprising an input gear 132, anoutput gear 142, at least one electric motor gear 120, wherein the input gear 132 is configured to connect via an input shaft 130 to an engine 1200, preferably via a torque converter 1300, of the truck 500, wherein the output gear 142 is configured to connect via an output shaft 140 to a transmission 1400 of the truck 500, wherein the at least one electric motor gear 120 is configured to connect to an electric motor 20, and wherein the output gear 142 and the at least one electric motor gear 120 are arranged to mesh with the input gear 132.

[0102] The input gear 132 serves as a central power distribution gear within the transfer case 100. Both the output gear 142 and the at least one electric motor gear 120 are arranged to mesh with the input gear 132. This arrangement enables power to be transferred from the torque converter 1300, via the input gear 132, to the transmission 1400 via the output gear 142, and simultaneously or alternatively, power to be transferred from the at least one electric motor 20, via the electric motor gear 120, to the input gear 132 and then to the output gear 142 and the transmission 1400. The common meshing of both the output gear 142 and the electric motor gear 120 with the input gear 132 enables bidirectional power flow, such that the electric motor 20 can both provide motive power to the drivetrain 1000 and regenerate electrical energy from the drivetrain 1000, without requiring any additional clutching or decoupling mechanisms within the transfer case 100.

[0103] The transfer case 100 may be specifically designed to operate in conjunction with a torque converter 1300. The torque converter 1300 provides important advantages in the context of large off-highway haul trucks 500, including dampening of shock loads that would otherwise be transmitted along the drivetrain 1000, and torque multiplication when the truck 500 is commencing movement from a stationary position under heavy load. The transfer case 100 receives the output of the torque converter 1300 via the input shaft 130, and the gear arrangement within the transfer case 100 is designed to accommodate the torque characteristics of the torque converter output, including the high torque multiplication that occurs during initial vehicle movement. The use of a mechanical friction clutch mechanism, independently of a torque converter 1300, as found in manual transmission vehicles, would be unsuitable for the high torque loads and operating conditions of off-highway haul trucks 500.

[0104] By providing the invention as a transfer case 100, the end user may opt to integrate the transfer case 100 into the truck 500 using optionally selected electric motors 20, and associated control unit 50 and motor controllers 30.

[0105] The system 10 according to the invention is able to facilitate either vehicle movement, or generation of power, in a number of different modes. A different mode may be applicable to different uses of the haul truck 500, with different modes being used for: down incline, flat, up incline, and stationary.

[0106] The control unit 50 may determine the operation of the motor controllers 30 to selectively engage the at least one motor 20 in a different manner for each mode.

[0107] When the truck 500 is driving down an incline, there is a need to maintain a constant safe maximum velocity. Conventionally this is achieved using either, or a combination of, brakes and engine braking, or, in the case of a diesel electric truck, by operating the electric motors as generators and offloading the electricity generated to resistors.

[0108] In each of these conventional examples, the energy is lost, and mechanical components may be worn to achieve the necessary constant safe maximum velocity.

[0109] In the case of the system 10 of the invention, when the vehicle is travelling down an incline, the at least one motor 20 operates as a generator, providing resistance. The resistance is transferred via the transfer case 100 and the transmission 1400 to the wheels 1600, restricting the speed accordingly. The electricity generated by the at least one motor 20 is stored in the battery 40, which may be achieved via the motor controller 30. Storing the energy then allows for it to be used in another application, to drive the at least one electric motor 20.

[0110] The arrangement of the invention therefore reduces wear on the engine 1200 and brakes, and conserves energy for subsequent use.

[0111] When the truck 500 is driving along a flat surface, the wheels 1600 may be ultimately driven by either or both of the engine 1200 and the at least one electric motor 20.

[0112] It is envisaged in the preferred embodiment that, when driving along a flat surface, the engine 1200 is driving the wheels 1600. The engine 1200 maysimultaneously turn the at least one electric motor 20 to operate as a generator and charge the battery 40.

[0113] The gear arrangement of the transfer case 100 enables selective power transfer. When the electric motor 20 is not energised, power from the torque converter 1300 is transferred via the input gear 132 to the output gear 142 and thence to the transmission 1400, with the electric motor gear 120 and electric motor 20 freewheeling. When the electric motor 20 is energised, the electric motor gear 120 transmits torque to the input gear 132, which combines with or substitutes for the torque from the torque converter 1300. The transfer case 100 thereby enables the truck 500 to operate in a purely internal combustion mode, a purely electric mode, or a combined hybrid mode, without requiring any mechanical clutching or decoupling within the transfer case 100 itself. This is in contrast to in-line motor arrangements where the motor is always mechanically coupled in the power path and introduces rotational inertia and drag losses even when not providing motive power

[0114] The at least one electric motor 20 may be selectively engaged in different circumstances to charge the battery 40, so that an adequate level of charge is maintained. The control unit 50 may determine when factors and / or conditions are required to engage or disengage the at least one electric motor 20.

[0115] Factors may include, but are not limited to, whether the truck 500 is loaded or empty, whether the truck 500 is setting off from rest, whether the ground is entirely flat or inclined to some extent, weather conditions, and battery and fuel levels.

[0116] When the truck 500 is stationary, the at least one electric motor 20 may be selectively engaged if the engine 1200 is running, to charge the battery. It is common that engines 1200 are kept running for periods of time, for example whilst waiting for the truck 500 to be loaded, or for an allocated "green light" on a narrow road, or to provide power to the systems such as air conditioning, for the comfort of the operators.

[0117] In these circumstances, much of the energy created by the engine 1200 at idle is lost, whereas by engaging the at least one electric motor 20, some of the energy can be stored in the battery 40.

[0118] When the truck 500 is travelling up an incline, the at least one electric motor 20 and the engine 1200 are engaged to drive the wheels 1600. The control unit 50 controls the engine 1200, the torque converter 1300 and the motor controller 30 to provide the required torque to the input shaft 130 and the electric motor gear 120 simultaneously, so that the required power is provided to the output shaft 140, and in turn the transmission 1400 and the wheels 1600.

[0119] The contribution to the provision of power by the at least one electric motor 20 reduces the load on the engine 1200, which in turn reduces fuel consumption and emissions, and wear on the components of the engine 1200. The reduced emissions may be particularly beneficial in underground mining applications, where the underground air quality is a significant concern.

[0120] By keeping the engine 1200 within narrower operating parameters, and not exposing the engine 1200 to extreme operating conditions, the wear is significantly reduced, and the time between service intervals, and overall life, can be increased.

[0121] It is further conceivable that an engine 1200 could be replaced with a smaller engine 1200, given the lower required duty as a result of the conversion to hybrid power according to the invention.

[0122] The skilled reader would readily appreciate the nature of the materials appropriate for making the components of the embodiments of the arrangements described herein. Modifications and variations as would be apparent to the skilled addressee are intended to be covered by the accompanying claims.

Claims

Claims1. A transfer case for use in hybrid conversion of a truck, the transfer case comprising an input gear, an output gear, at least one electric motor gear, wherein the input gear is configured to connect via an input shaft to an internal combustion engine of the truck, wherein the output gear is configured to connect via an output shaft to a transmission of the truck, wherein the at least one electric motor gear is configured to connect to an electric motor, and wherein the output gear and the at least one electric motor gear are arranged to mesh with the input gear.

2. The transfer case according to claim 1, wherein the truck is an off-highway haul truck.

3. The transfer case according to claim 1 or 2, wherein a distance that the input shaft and the output shaft are offset by is the same as the distance before the conversion.

4. The transfer case according to any one of the preceding claims, wherein the at least one electric motor gear is a first electric motor gear and a second electric motor gear, wherein the first electric motor gear is configured to couple to a first electric motor, and the second electric motor gear is configured to couple to a second electric motor.

5. The transfer case according to any one of the preceding claims, wherein the at least one electric motor gear is arranged to engage with the input gear via a spacer gear.

6. A system for hybrid conversion of a truck, the truck comprising an internal combustion engine, a torque converter, an original transfer case and a transmission, the system comprising a replacement transfer case, at least one electric motor, a motor controller, a battery and a hybrid system control unit.

7. The system according to claim 6, wherein the replacement transfer case is a transfer case according to any one of claims 1 to 5.

8. The system according to claim 6 or 7, wherein input shaft is connected to the torque converter, and the torque converter is connected to the internal combustion engine.

9. The system according to any one of claims 6 to 8, wherein the control unit is arranged to interface with the motor controller, the internal combustion engine, the transmission and the torque converter.

10. The system according to any one of claims 6 to 9, wherein the control unit is configured to control the speed of the internal combustion engine.

11. The system according to any one of claims 6 to 10, wherein the control unit is configured to adjust the amount of torque transmitted from the internal combustion engine to the input shaft of the transfer case.

12. The system according to any one of claims 6 to 11, wherein the at least one electric motor is two electric motors, being a first electric motor and a second electric motor.

13. The system according to claim 12, wherein the first electric motor is coupled to a first electric motor gear (or the first electric motor gear if dependent upon claim 4), and the second electric motor is coupled to a second electric motor gear (or the second electric motor gear if dependent upon claim 4), wherein the first electric motor gear and the second electric motor gear are arranged to engage with the input gear.

14. A method of converting a truck from an internal combustion powered drive train to a hybrid powered drive train, the truck comprising an internal combustion engine, a torque converter, an original transfer case and a transmission, wherein the original transfer case is arranged to transfer power from the torque converter to the transmission, the method comprising; removing the original transfer case, installing a replacement transfer case, wherein the replacement transfer case comprises at least one more gear than the original transfer case, and wherein the replacement transfer case is arranged to selectively transfer power from either or both of the torque converter or the at least one electric motor to the transmission.

15. The method according to claim 14, wherein the method further involves installing at least one electric motor, a motor controller, a battery and a hybrid system control unit.

16. The method according to claim 14 or 15, wherein the replacement transfer case is a transfer case according to any one of claims 1 to 5.

17. A kit of parts for converting a truck to hybrid power, the kit of parts comprising a replacement transfer case, at least one electric motor, a motor controller, a battery and a hybrid system control unit, wherein the transfer case is configured to engage with the at least one electric motor, a torque converter of the truck and a transmission of the truck.

18. A kit of parts according to claim 17, wherein the replacement transfer case is a transfer case according to any one of claims 1 to 5.

19. A hybrid truck comprising an internal combustion engine, a torque converter, a transfer case, at least one electric motor, a motor controller, a battery and a hybrid system control unit, wherein the transfer case is arranged to selectively transfer power from either or both of the torque converter and the at least one electric motor to the transmission.

20. A hybrid truck according to claim 19, wherein the transfer case is a transfer case according to any one of claims 1 to 5.

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