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Patent Searching and Data


Title:
A VEHICLE PROPULSION SYSTEM
Document Type and Number:
WIPO Patent Application WO/2019/013689
Kind Code:
A1
Abstract:
A vehicle propulsion system comprises a combustion engine (2) with a flywheel (3) secured to a crank shaft (4) of the engine. A starter motor and a generator are combined in one electric machine (10) having a stator (11) rigidly connected to a vehicle frame fixed part (8) and provided with windings (23) connected to an arrangement (24) storing electric energy for being fed with electric energy from the arrangement in motor operation of the electric machine and feeding electric energy to the arrangement in generator operation of the electric machine and a rotor (12) connected to the flywheel (3) so as to make the rotor and flywheel rotating in dependence of each other. At least one of the stator and rotor has a member (14, 15) projecting into a recess portion (17, 18) of the other so as to form air gaps (19-22) for magnetic flux between the rotor and the stator on both sides of the projecting member.

Inventors:
AREFI-SIGAROODI, Mehran (Marmorgatan 11, Stockholm, 118 67, SE)
DREHER, Holger (Terakottastigen 28, Södertälje, 151 55, SE)
Application Number:
SE2018/050732
Publication Date:
January 17, 2019
Filing Date:
July 04, 2018
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
SCANIA CV AB (151 87 Södertälje, 151 87, SE)
International Classes:
H02K21/24; H02K16/02; H02K23/54
Foreign References:
US20100072850A12010-03-25
US20130119789A12013-05-16
EP1102385A22001-05-23
US6459185B12002-10-01
US20120013216A12012-01-19
Attorney, Agent or Firm:
FORSELL, Hans (Scania CV AB, Södertälje, 151 87, SE)
Download PDF:
Claims:
A vehicle propulsion system comprising

a combustion engine (2) with a flywheel (3) secured to a crank shaft (4) of the engine,

a starter motor controllable to start the combustion engine, and

an electrical system comprising an arrangement (24) storing electric energy and to which the starter motor is connected to be fed thereby as well as a generator configured to generate electric energy to be delivered to said arrangement and electric equipment of the vehicle,

wherein the starter motor and the generator are combined in one electric machine (10) having a stator (11) rigidly connected to a vehicle frame fixed part (8) and provided with windings (23) connected to said arrangement for being fed with electric energy from the arrangement in motor operation of the electric machine and feeding electric energy to the arrangement in generator operation of the electric machine and a rotor (12) connected to the flywheel (3) so as to make the rotor and flywheel rotating in dependence of each other,

characterized in that at least one of the stator (11) and the rotor (12) has a member (14, 15, 14', 15') projecting into a recess portion (17, 18, 17', 18') of the other so as to form air gaps (19-22, 19'-22') for magnetic flux between the rotor and the stator on both sides of said projecting member.

A vehicle propulsion system according to claim 1, characterized in that said projecting member (14, 15) is projecting in parallel with an axis of rotation (16) of the flywheel (3) while forming a ring concentrically arranged with respect to said axis and received in a recess portion (17, 18), and that the projecting member and the recess portion are circular as seen in the direction of said axis of rotation (16).

A vehicle propulsion system according to claim 1, characterized in that said projecting member (14', 15') projects radially with respect to an axis of rotation (16) of the crank shaft (4) into a radially directed recess portion (17', 18').

A vehicle propulsion system according to claim 3, characterized in that the projecting member (14', 15') has an outer edge (30) concentrically surrounding said axis of rotation (16).

A vehicle propulsion system according to any of the preceding claims, characterized in that said at least one of the stator (11) and the rotor (12) has at least two said projecting members (14, 15, 14', 15') and the other equally many said recess portions (17, 18, 17', 18') each receiving such a projecting member.

A vehicle propulsion system according to any of the preceding claims, characterized in that at least the rotor (12) of the electric machine is received within an annular space (7) defined by an outer surrounding axially directed part (6) of the flywheel (3).

A vehicle propulsion system according to any of the preceding claims, characterized in that the rotor (12) is connected to the flywheel (3) through a gear (13).

8. A vehicle propulsion system according to claim 7, characterized in that the rotor (12) is connected to the flywheel (3) through a planetary gear (13).

9. A vehicle propulsion system according to claim 8, characterized in that the sun gear (26) of the planetary gear (13) is secured to the flywheel (3) and the ring gear (27) secured to the rotor (12).

10. A vehicle propulsion system according to any of the preceding claims, characterized in that it comprises a device controllable to change the relationship between the rotation speed of the flywheel (3) and the rotation speed of the rotor (12).

11. A vehicle propulsion system according to claims 8 and 10, characterized in that said device is controllable to change said relationship by acting upon the planetary gear (13).

12. A vehicle propulsion system according to any of the preceding claims, characterized in that the rotor (12) is provided with permanent magnets.

A motor vehicle, especially a heavy wheeled motor vehicle, such as a bus or a truck, characterized in that it is provided with a propulsion system according to any of the preceding claims.

Description:
A vehicle propulsion system

TECHN ICAL FI ELD OF TH E INVENTION The present i nvention relates a vehicle propulsion system comprising

• a combustion engi ne with a flywheel secured to a crank shaft of the eng ine,

• a starter motor controllable to start the combustion engi ne, and

• an electrical system comprising an arrangement storing electric energy and to which the starter motor is con nected to be fed thereby as well as a generator configured to generate electric energy to be delivered to said arrangement and elec- trie equipment of the vehicle.

The invention is di rected to such a propulsion system for all types of motor vehicles, although it is particularly directed to wheeled heavy motor vehicles, such as trucks and buses. The invention will for that sake hereinafter mainly be discussed for heavy trucks and buses so as to il luminate the invention but accordingly not restrict the i nvention thereto.

When constructi ng especially these types of motor vehicles there has been and is an ongoing attempt to make components smaller and less space demandi ng which has led to propulsion systems with small sizes of starter motors and generators and this has resulted i n an increased current-weight ratio. The consequences thereof may be a reduced qual ity and a hig her risk for very high temperatures and fire hazard. In spite of the smaller size of the starter motor and the generators they do together need a considerable space si nce the generator has to be ru n by a separate belt. BACKG ROUN D ART

US 6 278 1 96 B1 discloses a vehicle propulsion system of the type defined in the introduction in wh ich the starter motor and the generator are combined in one electric machine resulti ng in saving of weight and space.

SU MMARY OF TH E I NVENTION

The object of the present invention is to provide a vehicle propul- sion system of the type known through the publication mentioned above bei ng improved i n at least some aspect with respect to such known veh icle propulsion systems.

This object is according to the i nvention obtained by providing a vehicle propulsion system according to the appended patent claim 1 .

The construction of the electric machine thereof , which has a sta- tor rig idly connected to a vehicle frame fixed part and provided with windings con nected to the arrangement for being fed with electric energy from the arrangement in motor operation of the electric machine and feeding electric energy to the arrangement in generator operation of the electric mach ine and a rotor connected to the flywheel so as to make the rotor and flywheel rotati ng inde- pendent of each other, so that at least one of the stator and the rotor has a member projecting into a recess portion of the other so as to form air gaps for magnetic flux between the rotor and the stator on both sides of said projecti ng member the performance of the electric machine may be increased and an electric machine for a certain transfer of power may be made more compact, and thus space be saved. Thus, each air gap creates an additional torque, so that the torque transferrable through such an electric machine wi ll be increased by increasing the n umber of said air gaps. The creation of said air gaps by a member projecting into a recess portion makes the design of the electric machine even more compact.

Accordi ng to an embodiment of the invention said at least one of the stator and the rotor has at least two said projecti ng members and the other equally many said recess portions each receivi ng such a projecti ng member. By choosing the n umber of such ai r gaps the desired magnitude of torque of the electric machi ne may be obtained. Accordi ng to another embodi ment of the i nvention said projecting member is projecting in parallel with an axis of rotation of the flywheel while formi ng a ring concentrically arranged with respect to said axis and received in a recess portion , and the projecting member and the recess portion are circu lar as seen in the direction of said axis of rotation . Such a circular desig n of the projecti ng member and the recess portion makes it possible to obtain h igh torques transferrable between the stator and the rotor for a given size of the electric machi ne. Accordi ng to another embodi ment of the i nvention said projecting member projects radial ly with respect to an axis of the rotation of the crank shaft into a radially directed recess portion . The projecting member may then have an outer edge concentrical ly surround- ing the axis of rotation . This is another possible desig n of the projecting member and the recess portion resulting in a hig h possible torque for a given size of the electric mach ine.

According to another embodiment of the invention at least the rotor of the electric machine is received in an ann ular space defined by an outer su rrounding axially directed part of the flywheel . Using said an nular space normally present around a hub of the flywheel for separating the hub with respect to a mass of the flywheel located more distant to the axis of rotation of the flywheel for obtain- ing the required inertia of the flywheel to accommodate at least the rotor of the electric machine resu lts in a compact design of the vehicle propulsion system according to the invention .

According to another embodiment of the i nvention the rotor is con- nected to the flywheel throug h a gear, which means that this gear may be selected for obtain ing a desi red relationship between the rotation speed of the flywheel and that of the rotor.

According to another embodiment of the i nvention the rotor is con- nected to the flywheel through a planetary gear. This results in the possibility to change the relationship between the rotation speed of the flywheel , i .e. of the crankshaft, and the rotor by acting on the planetary gear so as to adapt this relationship to the operation mode of the electric machi ne, i .e. whether it is operated as a motor or as a generator. Accordi ng to another embodiment of the invention the sun gear of a planetary gear is secured to the flywheel and the ring gear secured to the rotor. This constitutes a suitable way of arrangi ng such a planetary gear, in which the sun gear may be arranged on a h ub of the flywheel .

Accordi ng to another embodiment of the invention the vehicle propulsion system comprises a device controllable to change the re- lationsh ip between the rotation speed of the flywheel and the rotation speed of the rotor. Such a device makes it possible to change this relationsh ip so as to be adapted to the actual operation mode of the electric machine. According to another embodiment of the invention said device is controllable to change said relationship by acti ng upon the planetary gear.

According to another embodiment of the invention the rotor is pro- vided with permanent mag nets, which promotes a high possible torque for a certai n size of the electric machine.

The i nvention also relates to a motor vehicle accordi ng to the appended claim directed to such a motor vehicle.

Further advantageous featu res as well as advantages of the present i nvention appear from the description followi ng below. BRIEF DESCRIPION OF THE DRAWING

With reference to the appended drawing, below follows a specific description of embodiments of the invention cited as examples.

In the drawing:

Fig. 1 is a schematic view showing a vehicle propulsion sys- tern according to a first embodiment of the invention in cross-section, and

Fig.2 is a view similar to that of fig. 1 of a part of the rotor and the stator of an electric machine in a vehicle pro- pulsion system according to a second embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Fig. 1 illustrates schematically a part of a vehicle propulsion system arranged in a vehicle 1 and having a combustion engine 2 with a flywheel 3 secured to a crank shaft 4 of the engine. The flywheel 3 has a central hub 5 and an outer part 6.

The flywheel is arranged in a casing 8 fixed to an engine block 9 fixed with respect to a frame of the vehicle. An electric machine 10 is arranged inside the casing 8 and has a stator 11 rigidly connected to the casing. A rotor 12 is connected to the flywheel 3 through a planetary gear 1 3. This rotor may be provided with permanent magnets i n the case of a permanent magnet electric machi ne. However, other types of electric machines, such as a synchronous electric machine, are also possible.

The stator is provided with two projecti ng members 1 4, 1 5 projecting in paral lel with an axis of rotation 1 6 of the flywheel 3 wh ile formi ng rings concentrical ly arranged with respect to th is axis and received in a recess portion 1 7, 1 8 each of the rotor 1 2. This means that air gaps 1 9-22 are formed on opposite sides of the respective projecti ng member for magnetic flux between the rotor and the stator.

Furthermore, the stator is provided with wi ndings 23 schematical ly indicated on each of the projecting members, and these windings are through an inverter 28 controlled by a control unit 29 connected to an arrangement 24 storing electric energy, such as 24V electric batteries 25. The su n gear 26 of the planetary gear is secured to the flywheel 3 and the ring gear 27 is secured to the rotor 1 2. Th us, the electric machine will nearly completely be arranged inside said annular space 7 of the flywheel 3 and by that demand a minim um of space. When starting the combustion engine 2 electric energy will be fed from the batteries 25 to the windings 23 of the stator 1 1 for drivi ng the rotor 1 2 and by that the flywheel 3 to rotate whi le functioning as a starter motor. Once the combustion eng ine is runni ng the electric machine may instead operate as a generator feeding electric energy from the stator windings to the electric batteries 25 and electric equipment of the vehicle. The number of air gaps so formed, the number of the poles of the electric machine as well as the ratio of the planetary gear may be chosen to adapt the electric machine to the requirements of the operation thereof as starter motor and generator. Fig.2 illustrates schematically the design of the rotor and the stator of the electric machine in a second embodiment of the invention, in which the rotor 12' has projecting members 14', 15' projecting radially with respect to an axis of rotation of the crankshaft into radially directed recess portions 17', 18' of the stator 11' so as to form air gaps 19'-22' axially directed for magnetic flux between the stator and rotor. The projecting members have an outer edge 30 concentrically surrounding the axis of rotation of the flywheel. The invention is of course in no way restricted to the embodiments described above, since many possibilities for modifications thereof are likely to be obvious to one skilled in the art without having to deviate from the scope of invention defined in the appended claims.