CO-PENDING APPLICATIONS

This application is filed concurrently with the application titled TWO- STAGE GEARBOX INTEGRATED IN AN ELECTRIC MOTOR ROTOR by the same applicant.

TECHNICAL FIELD

This application relates to a method of designing and/or producing a module for a propulsion axle with an electrical motor arrangement.

BACKGROUND

In the vast market that is the market for personal cars or automobiles, or more specifically for four wheeled cars for personal transport, there is a huge variety in the demands posed by the customers that a manufacturer need to take into account. These demands often relate to the overall cost, the operating cost, the acceleration, the top speed, the power and the range. For the car manufacturers to be able to

accommodate all demands and desires posed by the clients, the sub contractors as well as the car manufacturers must be able to provide compatible components and thereby compatible cars.

Manufacturers of wheel axles with electrical motors for four wheeled cars are also subjected to the same demands and to be able to provide a competitive product without sacrificing the quality it is of utmost importance to accommodate the end users' requirements and to do so at a low cost.

It is of course possible to build a propulsion axle and associated electrical motor from scratch for each set of requirements to make sure that all the requirements are properly met. However, such a procedure is not very cost-efficient and the finished product is not likely to be competitive on what is commonly known to be a highly competitive market. There is thus a need for a manner of manufacturing propulsion axles with electrical motors for four wheeled vehicles that is able to meet a wide range of requirements while still being highly cost efficient.

SUMMARY

It is an object of the teachings of this application to overcome the problems listed above by providing a method of producing a propulsion axle with an electrical motor arrangement for an electrical four wheel road vehicle. The method comprises receiving a requirement relating to propulsion axle performance, selecting a planetary gear set to provide a gear ratio, selecting an electrical motor from a small set of electrical motors, selecting a cooling arrangement to enable said electrical motor to provide a required output power, and arranging said planetary gear set, said electric motor and said cooling arrangement as an electrical motor arrangement module in a propulsion axle, said module being adapted to fulfill said requirement relating to axle performance.

By realizing that by limiting the choice of components to a few key components a wide range of performance characteristics can be achieved. The careful selection of the few key components is based on that the components should be of such type that they bring about a great influence on the overall performance when combined with the other components.

Further, the inventors realized that by using key components allows for a very small subset of each component to be available to select from while still being able to provide arrangements with a wide range of possible performances.

This provides a very simple solution to the complicated problems underlying the sophisticated design process of designing a module for an electrical drive axle assembly.

This manner of producing a module also has the benefit that a module can easily be ordered by giving simple specifications to a sub contractor and then easily be installed into a four wheeled vehicle.

The inventors have thus realized through insightful reasoning that by intelligently selecting certain key components a manufacturer only needs to keep a few versions of each component in stock and it also simplifies the design process of a new module. One benefit of such a module system is that a more cost-efficient product is provided, the logistics becomes easier and the maintenance of old models also becomes easier.

Also, the design of an arrangement using a modular system as disclosed herein is very easy and time efficient.

Further, the benefits of such a system are further amplified by an easy to use software modeling module as disclosed in the detailed description. BRIEF DESCRIPTION OF DRAWINGS

The invention will be described in further detail below under reference to the accompanying drawings, in which

FiglA shows a schematic view of a propulsion axle and electric motor arrangement module according to one embodiment of the teachings of this application;

Fig IB shows a schematic view of a propulsion axle and electric motor arrangement module according to one embodiment of the teachings of this application;

FiglC shows a schematic view of a propulsion axle and electric motor arrangement module according to one embodiment of the teachings of this application;

Fig ID shows a schematic view of a propulsion axle and electric motor arrangement module according to one embodiment of the teachings of this application;

Fig 2A shows a flowchart of method according to the teachings of this application;

Fig 2B shows a flowchart of method according to the teachings of this application;

Fig 2C shows a flowchart of method according to the teachings of this application;

Fig 2D shows a flowchart of method according to the teachings of this application;

Fig 2E shows a flowchart of method according to the teachings of this application; Fig 2F shows a flowchart of method according to the teachings of this application;

Fig 3 shows an example embodiment of an example user interface according to the teachings of this application, and

Fig 4 shows an example embodiment of an example user interface according to the teachings of this application.

DETAILED DESCRIPTION

In the automotive industry there exists a vast selection of different motor and propulsion axle designs and each design comprises a multitude of different parts and options. This offers a designer a wide range of components to choose from and to change when designing a new propulsion axle and electrical motor arrangement. To make the right selection is often a choice of great importance as it will affect the performance and price of the finished arrangement. The sophisticated operation of selecting the right components therefore requires a cumbersome and lengthy design process. Also, some designs will require that special parts are made especially for that design which lengthens production time and increases the overall cost of the

arrangement.

In order to be able to provide a propulsion axle and electrical motor

arrangement, especially for personal cars and in particular especially for electrical, four- wheeled drive personal cars in an easy to design and cost-efficient manner, the inventors of the teachings of this application have designed a modular system. After much insightful reasoning and inventive thinking the inventors realized that a modular system based on a few key components provides a design system which is both easy to use, offers a great range of possibilities and is highly cost-efficient.

After careful reasoning and analysis the inventors came to the inventive insight and realized that a selection of key components such as described below would provide the necessary wide range of performance options to meet all future requirements from prospective clients. The inventors have thus provided a simple solution to a

sophisticated design process for solving the complicated problem of designing a module for an electrical drive axle assembly. The simple solution is made possible through an intelligent selection of key components. Figure 1 A shows a schematic view of a propulsion axle and electrical motor arrangement 100 for a four wheel automobile according to the teachings of this application. The arrangement 100 comprises a propulsion axle 110 adapted to connect two wheels 105 to an electrical motor 140. The motor 140 is operative ly connected to the axle 110 through a planetary gear set 120.

The use of planetary gear sets 120 makes it possible to connect a wide variety of different components to an axel in an easy manner. The focus on planetary gear sets 120 is thus ingenious in that it simplifies combining different components without requiring any significant modifications.

How the planetary gear set 120 is arranged on a wheel axle arrangement is disclosed in application WO 20100101506 by the same applicant, where the planetary gear set 120 includes two planetary gears for providing a differential functionality.

In one embodiment the planetary gear sets 120 available are one providing a ratio of about 5.7 and one providing a ratio of about 8.3. That is, determining a planetary gear set 120 having the desired ratio includes the selection of two planetary gears, each having the same ratio.

In one embodiment there are two different electrical motors 140 to choose from, one with a high torque and one with a low torque. In one embodiment the electrical motor has a peak power of 20 kW. In one embodiment the electrical motor has a peak power of 60 kW. This makes it very easy to select an appropriate motor for a specific requirement specification compared to selecting an electrical motor from the vast offering of electric motors on a contemporary market. Also associated with the motor 140 is a cooling system 130. In the schematic view of figure 1 the cooling system is shown to be a separate unit, but it should be understood that the cooling system 130 can also be incorporated in the motor 140. The cooling system 130 is selected to control the level of continuous power delivered from the electric motor 140.

In one embodiment there are two types of cooling systems 130, one internal and one external.

In one embodiment there are two types of external cooling systems 130 using different cooling fluids, one water and one air. A water cooling system 130 provides a higher continuous power from the electrical motor 140. An air cooling system 130 provides a lower continuous power from the electrical motor 140. It should be noted that other cooling systems are also possible to use in a modular system such as disclosed herein. It should be noted that other cooling systems such as oil cooling is also possible.

In one embodiment there are two types of internal cooling systems 130 designed to work with different flows, either high flow or low flow. A cooling system 130 working with a low flow provides a low continuous power and a cooling system 130 with a high flow provides a high continuous power.

WO2011089564, claiming priority from SE 1000071-9 by the same applicant discloses a cooling system which can beneficially be used as a cooling system 130 in a module as disclosed herein.

Other benefits and disadvantages of the four different types of cooling systems 130 are known to a person skilled in cooling and such a skilled person will be able to select the appropriate cooling system to meet the specific requirements.

In the embodiment of figure 1 A only three different components are used, namely the motor 140, the cooling system 130 and the planetary gear set 120 and a designer thus only have to select three different components which makes the design process very easy. It also allows a manufacturer to only have a warehouse storing three different types of components which components can all be used for different designs. The advantages of this should be clear in that it will be easier to keep an updated storage among other benefits. Furthermore, as only a few key components are needed manufacturers of such components may streamline their production further as there will be a demand for only a few components model allowing the manufacturer to focus his production on these components thereby reducing the production costs in that larger volumes are produced and less machinery (at least types of machinery). Also, the number of spare parts that are needed is reduced and also the training of technical or support staff as fewer components need to taught to the support or technical staff.

Figure 2A shows a flow chart of a method according to the teachings of this application. The basic concept is that the planetary gear set 120, including two planetary gears having the same gear ratio, may be combined with a reduction gear for providing four different fixed gears as well as two options of a controllable two-stage reduction gear. By combining the gear concept with two electrical motors having different characteristics as well as with different modular cooling concepts a wide range of power and torque ranges may be provided.

In a first step 210 a requirement specification is received. Thereafter a designer selects a planetary gear set to provide a suitable gear ratio 220. The planetary gear set 120 is selected from a small set of possible planetary gear sets 120. In one embodiment there is two planetary gear sets 120 to select from, each planetary gear set including two planetary gears having the same ratio. The designer also selects an electrical motor 140 to provide a suitable torque 230. The electrical motor 140 is selected from a small set of possible electric motors 140. In one embodiment there are two electrical motors to select from. Thereafter a cooling system 130 is selected to provide a suitable continuous power output 240. In one embodiment the cooling system 130 is selected to be either external or internal. In a final step the arrangement is assembled in step 280.

This provides a manner to produce a propulsion axle with an electrical motor arrangement 100 by only selecting a very few number of components from an easy to overview subset of available components to meet a wide range of possible requirements.

In one embodiment the requirement specification is analyzed to find a suitable arrangement of components step 215, see fig 2B, by determining the characteristics of the module. The analysis is performed by a computer or other calculative means in one embodiment. The analysis is based on that the size requirements and the price requirements are matched against the different alternatives for the various components to match against the required performance of the propulsion axle.

As the number of components is quite low (in this application up to 6) and the options for each component are also low the total number of combinations is limited and an exhaustive matching is therefore possible. In the example of table 1 (see further on), where there are six components each having two options, the total number of combinations is 2 ⁶ = (2 raised to the power of 6) = 64. A designer would therefore be able to easily input the requirements and then by himself, or using a computer, match the requirements (both cost and performance and other) to the possible combinations, one combination at a time or through a more insightful selection. It should be noted that the set of components is kept small and that a small set is to be understood to be a set that can be easily overviewed and for which the number of available combinations is not to large but to be handled in a manner that is possible to perform manually.

The number of components to be selected is preferably below or equal to 7 and the number of options for each component is less than or equal to 4.

In an embodiment where at least one component is preselected the number of available combinations, in the example above, is reduced to 32.

The first choices are often the most easy to make as some choices will be more or less apparent to a designer. For example, if a high-power machine is to use the resulting module the low-power motor will not be an option. Also, if a vehicle that possibly traverses rough terrain (such as heavy duty jeeps) air cooling is perhaps not an option.

In one embodiment the computer or other calculative means is arranged to perform at least a partial analysis for selecting the needed components. In one such embodiment the computer makes a preliminary determination of the key components needed (for example a high power motor for an assembly to be used in a high- performance vehicle) and the designer or user selects the remaining components. In one such embodiment the designer or user makes a preliminary determination of the key components needed (for example high power motor for an assembly to be used in a high-performance vehicle) and the computer selects the remaining components after analyzing the selected components and the specifications.

In one embodiment where a computer or other calculation means provide a full or partial proposal for components to be selected a user or designer is enabled to amend or change the proposed selection. In one such embodiment the computer is arranged to adapt the proposal for selection of components according the user's or desinger's changes.

One benefit of calculating the resulting performance for each combination when an arrangement is to be designed is that it takes into account changes that might have been made recently to one or several components or their options.

It would also be possible to keep a list of the resulting performance and cost (and other characteristics) of all the possible combinations and simply match the requirements to this list selecting the combination which comes closest. One benefit of comparing to a list is that it can be checked very quickly even if the design phase is done manually.

Hence, it is obvious that the design phase for a propulsion axle and electrical motor becomes very simple using the module system as disclosed herein.

Figure IB shows a further embodiment where a fourth component is added to the modular arrangement 100. The fourth component is a reduction stage 150. The reduction stage 150 is arranged so as to co-operate with the planetary gear set 120 to provide a suitable overall gear ratio. In one embodiment the reduction stage 150 is arranged to provide a gear ratio of about 1.7. The arrangement of the reduction stage 150 is selected from the group of being connected in series with a planetary gear set 120, in series with a disconnect (more on this below) or in a selectable 2-step gear box (more on this further below). The reduction stage 150 and its arrangement are selected in a step 250, see fig 2C. One example of a reduction stage 150 that can be used is disclosed in the application titled TWO-STAGE GEARBOX INTEGRATED IN AN ELECTRIC MOTOR ROTOR filed concurrently as this application and by the same applicant.

Figure 1C shows a further embodiment where a fifth component is added to the modular arrangement 100. The fifth component is a disconnect 160. In one embodiment having an external cooling system 130 the disconnect 160 chosen to have one clutch arrangement for a disconnect function or to have two clutch arrangements for a two-step gear box arrangement.

For an internal cooling system 130 operating at a high flow the disconnect 160 can be chosen to have one valve for a disconnect function or two valves for a two-step gear box arrangement.

The disconnect 160 and its arrangement are selected in a step 260, see fig 2D.

Figure ID shows a further embodiment where a sixth component is added to the modular arrangement 100. The sixth component is a torque vectoring unit 170. Torque vectoring units are described in the application WO2010101506 by the same applicant. A torque vectoring unit has the advantage of allowing or improving traction control as is also disclosed in the application WO2010101506.

The torque vectoring unit 170 is selected in a step 270, see fig 2E. It should be noted that although the reduction stage 150, the disconnect 160 and the torque vectoring unit 170 have been referred to as the fourth, fifth and sixth components respectively the order of selecting them is by no means limited by these references. An embodiment having a reduction stage 150 and a torque vectoring unit 170, but no disconnect is plausible as is any other combination of these components.

It should also be noted that even though the figures only show one selection of the reduction stage 150, the disconnect 160 and the torque vectoring unit 170 they can be selected in any combination and figure 2F shows an embodiment where all three are selected.

A module for a propulsion axle and an electrical motor resulting from a combination as disclosed above can generate continuous power outputs of 5 to 40 kW and maximum torque from 400-3200 Nm which fully covers most prospective clients' requirements.

In one example embodiment a combination of a 60 kW electrical motor 140, an external water cooling system 130, a reduction stage 150 with a ratio of 1.7, a planetary gear set 120 including two planetary gears with a ratio of 5.7 and a selectable two-step disconnect 160 and a torque vectoring unit 170 provides a propulsion axle and electrical motor arrangement generating a total performance of continuous power of 40 kW, a maximum torque of 2000 Nm and a maximum speed of 250 kph.

In one example embodiment a combination of a 60 kW electrical motor 140, an external water cooling system 130, a planetary gear set 120 including two planetary gears with a ratio of 8.3, a direct disconnect 160 and a torque vectoring unit 170 (no reduction stage 150) provides a propulsion axle and electrical motor arrangement generating a total performance of continuous power of 40 kW, maximum torque of 1800 Nm and a maximum speed of 160 kph.

In one example embodiment a combination of a 20 kW electrical motor 140, an external air cooling system 130, a reduction stage 150 with a ratio of 1.7, a planetary gear set 120 including two planetary gears with a ratio of 8.3 and a direct disconnect 160 provides a propulsion axle and electrical motor arrangement generating a total performance of a continuous power of 5 kW, a maximum torque of 1000 Nm and a maximum speed of 100 kph. To illustrate how simple and easy to use a design process according to the teachings herein is to use an example of a user interface is shown in figure 3.

The user interface 300 in figure 3 shows a screen image where a user can select the components. Each component is presented for selection to a user through a displayed icon 310, one for each option. In the user interface 300 6 major options are shown, two for the motor (20 kW and 60 kW), two for the cooling (AIR and H20) and two for the planetary gear (5.7 and 8.3). I the example of figure 3, a user has made three selections which are marked by the corresponding icon having a thicker border. In this example the selection is MOTOR 20 kW, COOLING: AIR, GEAR 8.3.

The resulting characteristics for the electrical drive axle assembly are shown in a result view 320. In this example characteristics such as the power, the maximum torque, the cost and the availability of components for the assembly are shown. Also, graphs or diagrams 340 may be shown to illustrate certain characteristics. This provides the designer with a quick and clear view of the characteristics of a resulting electrical drive axle assembly. It also provides financial data such as cost and/or availability which may be beneficial to sales or support staff.

In an alternative embodiment, icons 330 for further components are also displayed in the user interface 300. The further components may be a reduction stage (150), a torque vectoring unit (170) and/or a disconnect (160). In the example of figure 3 the reduction stage is selected.

It should be noted that the user interface may have a different screen layout than the one shown in figures 3 and 4. For example the icons 310, 330 and 315 may be shown as bullets, drop-down menus or similar. Also, the number of further components may be different and other further components may alternatively or additionally be displayed. Or, no further components are displayed.

By using a user interface 300 such as in figure 3 a designer is thus able to design a complicated electrical drive axle assembly by simply clicking on 3 to 6 icons 310, 330.

It should be clear that due to the simplicity of a design procedure according to herein the actual design of an electrical drive axle system can be made by a lay person, for example a sales person perhaps even during a sales meeting. The sales person would thus be able to give an exact quota based on the availability of all major parts that are required for a specification without having to directly consult an engineer.

Figure 4 shows an alternative user interface 300 which is arranged with at least one input field through which a user can enter requirements or specifications. The user interface is arranged to feed such requirements to a computer or other calculative means arranged to perform a method according to herein and at least partially propose components to be used. In this example the electrical motor of 60 kW is proposed (as is indicated by the corresponding icon 315 being selected). The designer may then supplement or complement the proposal by selecting or deselecting icons, for example by selecting the icon for a reduction stage 330.

The user interfaces 300 of figures 3 and 4 thus enable a designer or user to design an electrical drive axle assembly in a manner that is simple and easy to use. The user interface 300 of figure 4 further enables a user to simply enter requirements and be provided with a proposal (at least partial) of what components should be part of the required electrical drive axle assembly in a manner that is simple to use and to overview.

The ingenious simplicity of the method and manner taught herein should thus be clear from the illustration of an example user interface 300 for implementing the method and manner.

A further benefit of the teachings herein is that it is easy to overview the technical requirements for a whole array of different arrangements. Table 1 shows an example of such an overview where a number of models of arrangements are listed and their selected components respectively. As can be seen from table 1 it is easy for both a designer and for the logistics manager to quickly get an overview of the available components and also which components are necessary to keep in stock.

Motor, kW Cooling Planetary Reduction Torque Disconnect

Model 60 20 Water Air 5.7 8.3 Vectoring

Ml X X X O

M2 X X X O M3 X X X X 0

M4 X X X X 0

M5 X X X X X X

Table 1 Overview of models and associated components.

X: required component, O: optional component.

The models presented in Table 1 are examples only, and further combinations are available. For example, the disconnect component may be optional for all models.

Another benefit of a modular system as disclosed herein is that simulation and planning of manufacturing propulsion axle and electrical motor modules becomes highly intuitive and easy to implement and as simulation is a big part of the automotive industry this is a major benefit.

According to another aspect of the teachings herein there is provided a software modeling module. The user interface of the software modeling module comprises a table similar to table 1. In the user interface a user simply marks the options wanted and the software modeling module calculates the resulting performance and displays it on a screen. Such a modeling module is employed in the analysis step 215 in one embodiment.

It should thus be clear that selecting from the cleverly selected subset of available components a wide range of performance requirements can be met in a highly cost-efficient manner resulting in competitive propulsion axle and electrical motor arrangements for electrical four wheel vehicles, especially for four-wheel drive.