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Title:
HYBRID VEHICLES WITH AUXILIARY LOADS
Document Type and Number:
WIPO Patent Application WO/2015/079238
Kind Code:
A2
Abstract:
The invention relates to the field of hybrid vehicle propulsion systems, where there is more than one source of on-board rotary motion. A hybrid vehicle comprises a battery (10) for powering means for driving the vehicle, a motor/generator (40) having a motor/generator shaft (45), and an engine (50) having an output shaft (55). The engine output shaft (55) is coupled to the motor/generator shaft (45) by a one-way clutch (70). The one-way clutch (70) is arranged to allow the motor/generator (40) to rotate faster than the engine output shaft (55), and does not allow the engine output shaft (55) to rotate faster than the motor/generator shaft (45). The one-way clutch (70) is arranged to never transmit torque from the motor/generator shaft (45) to the engine shaft (55), and to transmit torque from the engine output shaft (55) to motor/generator (40) output when the clutch (70) locks the engine output shaft (55) and the motor/generator shaft (45) together to rotate to the same speed. The hybrid vehicle comprises one or more auxiliary loads (60), the one or more auxiliary load(s) (60) being connected directly to the motor/generator output shaft (45) so that the one or more auxiliary loads (60) are driven whenever the motor/generator shaft (45) rotates. The auxiliary load(s) (60) is/are driven by motor/generator (40) alone when the motor/generator (40) functions as a motor and rotates the motor/generator shaft (45) faster than the engine output shaft (55). The auxiliary load(s) (60) is/are driven by the engine (50) when torque is transmitted via the one way clutch (70) from the engine output shaft (55) to the motor/generator (40).

Inventors:
SCHEY ALEXANDER (GB)
SCHULZ TOBY (GB)
Application Number:
PCT/GB2014/053516
Publication Date:
June 04, 2015
Filing Date:
November 27, 2014
Export Citation:
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Assignee:
VANTAGE POWER LTD (GB)
International Classes:
B60K6/383
Attorney, Agent or Firm:
BOULT WADE TENNANT (70 Grays Inn Road, London Greater London WC1X 8BT, GB)
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Claims:
CLAIMS :

1. A hybrid vehicle, comprising:

a battery for powering means for driving the vehicle; a motor/generator having a motor/generator shaft; and an engine having an output shaft,

wherein :

the engine output shaft is coupled to the

motor/generator shaft by a one-way clutch;

the one-way clutch is arranged to allow the

motor/generator to rotate faster than the engine output shaft and does not allow the engine output shaft to rotate faster than the motor/generator shaft; and

the one-way clutch is arranged to never transmit torque from the motor/generator shaft to the engine shaft and to transmit torque from the engine output shaft to

motor/generator output when the clutch locks the engine output shaft and the motor/generator shaft together to rotate to the same speed,

wherein:

the hybrid vehicle comprises one or more auxiliary loads; and

the one or more auxiliary load(s) are connected

directly to the motor/generator output shaft so that the one or more auxiliary loads are driven whenever the

motor/generator shaft rotates, whereby:

the auxiliary load(s) is/are driven by motor/generator alone when the motor/generator functions as a motor and rotates the motor/generator shaft faster than the engine output shaft; and the auxiliary load(s) is/are driven by the engine when torque is transmitted via the one way clutch from the engine output shaft to the motor/generator . 2. The hybrid vehicle of claim 1, wherein the clutch is a mechanical clutch.

3. The hybrid vehicle of any preceding claims, further comprising a controller, wherein the controller controls the engine based upon the power drawn by the auxiliary loads.

4. The hybrid vehicle of claim 3, wherein the controller commands the engine to run at a speed or torque determined in dependence upon the power drawn by the auxiliary loads.

5. The hybrid vehicle of claim 3 or claim 4, wherein the controller measures the power drawn by the auxiliary loads using :

the speed of the motor/generator shaft 45;

the torque applied by the motor/generator 40; and the torque applied by the engine 50.

6. The hybrid vehicle of claim 3 or claim 4, wherein the controller measures the power drawn by the auxiliary loads using:

the speed of the motor/generator shaft 45; and

the speed of the engine shaft 55.

7. The hybrid vehicle of any preceding claims, wherein the one or more auxiliary loads are connected to the

motor/generator output shaft via a belt or pulley.

8. The hybrid vehicle of any preceding claims, wherein the one or more auxiliary loads include one or more of: an oil pump; a cooling pump; a cooling fan; a hydraulic pump; an air conditioning system; an air compressor.

9. A series hybrid vehicle according to any preceding claim .

10. The series hybrid vehicle of claim 9, wherein further comprising an electric motor.

11. The hybrid vehicle of claim 9 or claim 10, wherein the electric motor and the battery are mounted on a first sub- frame, and the motor/generator and the engine are mounted on a second sub-frame.

12. The hybrid vehicle of claim 11, wherein the second sub- frame is slidably and detachably mounted on the first sub- frame .

13. A parallel hybrid vehicle according to any one of claims 1 to 8.

Description:
HYBRID VEHICLES WITH AUXILIARY LOADS

The invention relates to the field of hybrid vehicle

propulsion systems, where there is more than one source of on-board rotary motion.

In a hybrid vehicle, an internal combustion engine can be configured to drive a motor/generator, which generates electricity to charge an electrochemical or electrical storage system and/or power an electric motor (typically known as a series hybrid vehicle); or can be configured to drive the wheels of the vehicle in conjunction with an electric motor and/or charge an electrochemical or

electrical storage system using said electric motor

(typically known as a parallel hybrid system) .

It is often the case that such a system will power further auxiliary equipment which are essential for those vehicle's operation and require rotary input. It is known to drive the auxiliary loads directly from the internal combustion engine. However, in a hybrid vehicle it is preferable that the internal combustion engine can be deactivated so that the vehicle may be driving under electric power only, in which case an alternative means of providing power to the auxiliary loads is required.

There is therefore a need in the art for an efficient and more cost effective method of driving auxiliary loads in a hybrid vehicle.

According to the invention, there is provided a hybrid system defined by claim 1. For a better understanding of the invention and to show how the same may be put into effect, reference is now made, by way of example only, to the accompanying drawings in which:

Figure 1 shows a schematic representation of a series hybrid system;

Figure 2 shows a layout of components in the system of Figure 1; and

Figure 3 shows a schematic representation of a parallel hybrid system.

The invention has utility in both series and hybrid

architectures. Figure 1 shows a first embodiment in the form of a series hybrid system.

The series hybrid system of Figure 1 comprises: a battery 10, an electric motor 20; a primary load 30; a

motor/generator 40; an engine 50; and one or more auxiliary load(s) 60.

Preferably, inverters 5, 15 are provided to convert the charging current to DC and to provide the driving current in AC (although DC motors and a DC motor/generator are

possible) .

The electric motor 20 is arranged to drive the primary load 30. The electric motor 20 is powered by one or both of the battery 10 and/or the motor/generator 40. The battery 10 is arranged to supply electricity to the electric motor 20 and/or receive charge from the

motor/generator 40. The engine 50 has an output shaft 55.

The motor/generator 40 has a shaft 45, which is driven by the output shaft of the engine 50. The output shaft 55 of the engine 50 is coupled to the shaft 45 of the motor/generator 40 by a one-way clutch 70.

The one-way clutch 70 is not automated or controlled in any way. The one-way clutch 70 is preferably a mechanical clutch. Most preferably, the one-way clutch 70 is a sprag clutch .

The one-way clutch always allows relative rotation between the engine shaft 55 and the motor/generator shaft 45 in a first direction of rotation. The one-way clutch always prevents relative rotation between the engine shaft 55 and the motor/generator shaft 45 in a second direction of rotation . The one-way clutch 70 is arranged to never transmit torque from the engine 50 to the motor/generator 40 when the engine shaft 55 rotates in a first direction at a lower rotational speed than the motor/generator shaft 45. In this way, the one-way clutch 70 is arranged to transmit torque from the engine 50 to the motor/generator 40 when the engine shaft 55 rotates in a first direction at a rotational speed matching that of the motor/generator shaft 45; Once the speed of the engine shaft is increased to match the speed of the motor/generator shaft 45 and then thereafter, as the speed of the engine shaft increases further, the engine shaft and the motor/generator shaft are locked to rotate together at the same speed.

Previously it has been conventional for the motor/generator 40 to act as a starter motor for the engine 50, but the inventors have adapted a different approach by providing a one-way mechanical clutch between the motor/generator 40 and the engine 50 have arranged for, the auxiliary load(s) 60 to be driven in a more efficient way. As can be seen in Figure 1, the auxiliary load(s) 60, which may be driven via a shaft 65 are coupled directly to the motor/generator 40 and rotation of the motor/generator shaft 45 drives the auxiliary load(s) 60. For example, at least one auxiliary load 60 may be driven via a shaft 65, which is directly coupled to the

motor/generator shaft 45 via a belt and pulley 80.

The series hybrid system of the invention is therefore arranged such that the engine 50 will drive the

motor/generator 40 and auxiliary loads 60 when the

motor/generator 40 is acting as a generator. However, the engine 50 will not drive the motor/generator 40 and

auxiliary loads 60 when the motor/generator 40 is acting as a motor and in this condition the motor/generator 40 is used to drive the auxiliary loads 60. A hybrid system such as that described above can therefore use the battery 10 to power the motor/generator 40 to drive the auxiliary load(s) 60 when the engine 50 is deactivated, warming up, or idling. In such operating conditions the motor/generator 40 drives the auxiliary loads 60 without also driving the engine shaft 55 to rotate, since the oneway clutch 70 allows the shaft of the motor/generator 40 to rotate relative to the engine shaft 55 in the first

direction .

On start-up of the engine 50 there is therefore a seamless transition as the engine 50 rotational speed increase up to its operating point. Until the engine 50 rotational speed reaches the rotational speed of the motor/generator 40 in the first direction, the clutch 70 will allow relative rotation between the engine shaft 55 and the motor/generator shaft 45.

Once the engine 50 rotational speed has reached the

rotational speed of the motor/generator 40 in the first direction, then the clutch 70 can transmit torque from the engine shaft 55 to the motor/generator shaft 45. Thus, the engine can be used to drive the motor/generator 40 and the auxiliary load(s) 60.

The provision of the one-way clutch 70 thus allows the hybrid system to drive the auxiliary load(s) 60

independently of the engine speed. A starter motor separate to the motor/generator 40 is preferably provided. In particular, some engines require a starter motor, and in the disclosed series hybrid system the provision of the clutch 70 prevents the motor/generator 40 from acting as a starter motor.

It is envisaged that the above-disclosed series hybrid system will be useful in hybrid vehicles (for example, hybrid automobiles) . Preferably, large vehicles (e.g., those weighing more than 7.5 tonnes) are considered, such as buses, coaches, or lorries. Series hybrid vehicles may have auxiliary loads including one or more of: an oil pump; a cooling pump; a cooling fan; a hydraulic pump; an air conditioning system; an air

compressor for a vehicle braking system; and/or an air compressor for a vehicle suspension system.

The system described above with reference to Figure 1 (and the system described below with reference to Figure 3) greatly benefits from the provision of a controller 90 that sets the torque or speed of the engine 50 (when in use) in dependence upon the power drawn by the auxiliary loads 60.

Since the power collectively drawn by the auxiliary loads 60 is difficult to measure directly, preferred embodiments determine this by measuring the speed of the motor/generator shaft 45, the torque applied by the motor/generator 40, and the torque applied by the engine 50.

For example, the power drawn by the auxiliary load 60 may be estimated as the speed of the motor/generator shaft 45 multiplied by the difference in torque between the engine shaft 55 and the motor/generator shaft 45. The torques applied by the engine 50 and motor/generator 40 need not be measured directly. These can be determined from one or more parameter (s) of the engine 50 and

motor/generator 40, using a look-up table calibrated using a dynamometer. In other words, the parameter (s) of the engine 50 and the parameter (s) of the motor/generator 40 can be used to determine the difference in torque between the engine shaft 55 and the motor/generator shaft 45. For example, the engine 50 torque may be determined from the speed of the output shaft 55 (for example, if the engine has been calibrated to run with a particular fuel rate) . It is also possible to determine the engine 50 torque from the speed of the output shaft 55 and one or more of: fuel rate; fuel injection timing; ambient humidity; pressure; engine air inlet temperature; and ambient temperature.

Similarly, the motor/generator 40 torque may be determined from the speed of the output shaft 45, or the speed of the output shaft 45 and one or more of: driving voltage; and drawn current .

A sensor 95 for each of the engine shaft 55 and the

motor/generator shaft 45 may be used to provide the

controller 90 with speed and/or torque information.

In preferred embodiments, the controller 90 is arranged to determine the most fuel efficient operating point for the engine 50 using the measurement of power drawn by the auxiliary loads 60. In preferred embodiments, the controller 90 uses the

measurement of power drawn by the auxiliary loads 60 to prevent the engine 50 from stalling. For example, the controller 90 may ensure that the torque applied by the engine 50 exceeds the torque required to power the auxiliary loads 60 for a given engine speed.

As would be appreciated by the Skilled Person, each of the engine 50 and motor/generator 40 is preferably controlled by providing either a speed or a torque signal (it is not necessary to provide both) . Whilst it is preferred to dictate the engine 50 speed and motor/generator 40 torque, embodiments are considered in which the engine 50 torque is controlled and embodiments are considered in which the motor/generator 40 speed is controlled.

The controller 90 may also control the motor/generator 40 when acting as a motor to drive the auxiliary loads 60. The controller 90 may also be used to bring the engine 50 up to speed when it starts during a period in which the

motor/generator 40 is acting as a motor to drive the

auxiliary loads 60. The controller 90 may control the engine speed when it is initiated to increase it to the speed of the generator/motor . The controller 90 may reduce the rate of increase of the engine speed as it approaches the speed of the generator/motor . This can prevent a high impact as the one-way clutch 70 locks the engine shaft 55 to rotate with the motor/generator shaft 45.

Preferably, the engine 50 is an internal combustion engine. In large vehicles (e.g., those weighing more than 7.5 tonnes), such as buses, coaches, or lorries, the engine size is preferably from 2 to 5 litres. Since the engine is not used to directly drive the wheels of the vehicle it can be operated for the majority of the time in a narrow band of operating conditions of engine speed and load in which the engine efficiency is maximised.

It is conventional in vehicle maintenance to consider the engine to be such an intrinsic part of the vehicle that any engine problems are considered to be serious enough that the vehicle must be taken off the road until fixed. This is particularly the case in large vehicles in which the engines must be large to provide the required torque. However, in series hybrid vehicles, in which the engine is not the prime mover, this does not need to be the case.

The inventors have envisaged assembling a series hybrid system in a vehicle in such a way as to allow easy removal of the engine 50 from the hybrid system.

In the embodiment depicted in Figure 2, the series hybrid system is mounted on a frame having at least two sub-frames.

The battery 10 and the electric motor 20 are mounted on a first sub-frame 110, while the motor/generator 40 and the engine 50 are mounted on a second sub-frame 120.

Preferably, the sub-frames are arranged such that the sub- frames may be decoupled (for example, slidably decoupled) . In the example shown in Figure 2, the second sub-frame 120 may be slid into the first sub-frame 110. Thus, when there is a mechanical problem with the engine 50, it is not necessary to stop using the entire vehicle.

Instead, the second sub-frame 120, along with the

motor/generator 40, the engine 50, and the one or more auxiliary load(s) 60, may be simply removed from the first sub-frame and replaced. The components mounted on the removed second sub-frame 120 may thus be serviced

independently of the vehicle.

Figure 3 shows a second embodiment in the form of a parallel hybrid vehicle.

As can be seen in Figure 3, a one-way clutch of the type described above is used to couple the output shaft 45 of the motor/generator 40 to the output shaft 55 of the engine 50.

As with the first embodiment, the auxiliary load(s) 60 is/are coupled directly to the motor/generator 40.

Preferably, a controllable clutch 200 is provided between the motor/generator 40 and the vehicle transmission.




 
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