# US 8,465,392 B2 · Method for operating a vehicle hybrid drive train having an internal combustion engine and having an electric machine

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- Number: US 8,465,392 B2
- Document ID: US8465392B2
- Status: Granted
- Kind: B2
- Application number: 13/123,735
- Filed: 2009-11-18
- Published: 2011-11-17
- Granted: 2013-06-18
- Earliest claimed: 2008-12-02
- Assignees: ZF Friedrichshafen AG
- Applicants: Bernd Allgaier; Michael Sohler; Peter Schiele
- Inventors: Bernd Allgaier; Michael Sohler; Peter Schiele
- Web page: https://patentgrep.com/patent/US8465392B2

## CPC

- B60W 20/30: Control strategies involving selection of transmission gear ratio {(control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H)}
- B60K 6/48: Parallel type
- B60W 10/08: including control of electric propulsion units, e.g. motors or generators
- B60W 10/30: including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps
- B60W 30/18054: {at stand still, e.g. engine in idling state (hill holding B60W30/18118)}
- B60W 30/188: Controlling power parameters of the driveline, e.g. determining the required power
- F16H 61/0028: {using a single pump driven by different power sources}
- B60K 2006/268: {Electric drive motor starts the engine, i.e. used as starter motor}
- B60L 2240/421: Speed
- B60W 20/00: Control systems specially adapted for hybrid vehicles {(hybrid vehicle design, B60K6/00; electric vehicles B60L)}
- B60W 2710/081: Speed
- F16H 2312/14: Going to, or coming from standby operation, e.g. for engine start-stop operation at traffic lights
- Y02T 10/62: Hybrid vehicles
- Y02T 10/64: Electric machine technologies in electromobility
- B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- F16H: GEARING
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A method of operating a vehicle hybrid drive train comprising an internal combustion engine and electric machine whose torque is applicable to a drive output of the drive train. The drive train comprises a clutch arranged between the internal combustion engine and electric machine, an oil pump connected in the drive train downstream of the clutch in relation to the internal combustion engine, and the oil pump can be driven by the internal combustion engine and the electric machine, and a transmission which comprises a shifting elements for producing various gear ratios and which is supplied with hydraulic fluid by the oil pump in an operating-status-dependent manner. The speed of the electric machine is set independently of the speed of the internal combustion engine, in order to supply the transmission with a flow of a volume hydraulic fluid required for the operating point of the transmission present at the time.

## Claims

### Claim 1

A method of operating a vehicle hybrid drive train (1) comprising an internal combustion engine (2) and an electric machine (3) which are connected to the vehicle hybrid drive train such that torque from both the internal combustion engine and the electric machine is transmittable to a drive output (4) of the vehicle hybrid drive train (1), a clutch device (5) arranged between the internal combustion engine (2) and the electric machine (3) such that the internal combustion engine is roationally fixable to the electric machine, an oil pump device (7) arranged in the vehicle hybrid drive train (1), downstream of the clutch device (5), in relation to the internal combustion engine (2), and drivable by both the internal combustion engine (2) and by the electric machine (3), and a transmission device (6) which comprises a plurality of shifting elements for producing various gear ratios and which is supplied with hydraulic fluid by the oil pump device (7) in an operating-status-dependent manner such that a speed of the electric machine (3) is set, independently of a speed of the internal combustion engine (2), in order to supply the transmission device (6), in each case, with a hydraulic fluid volume flow required for an operating point of the transmission device (6) present at the time, the method comprising the steps of:
corresponding the speed of the electric machine (3) to an at-rest speed value which is lower than an idling speed of the internal combustion engine (2), when the vehicle is at least approximately at rest, such that the oil pump device (7) driven by the electric machine (3) maintains the shifting elements in an at least partially engaged condition so as to maintain a current operating status of the transmission device (6), and
increasing the speed of the electric machine (3), in a range when the vehicle is at rest, when there is at least one of a shift demand for a gear change from a starting gear to a higher gear step and a shift demand for a gear change from a higher gear step to a starting gear.

### Claim 2 (depends on 1)

The method according to claim 1, further comprising the step of, when the vehicle is at least approximately at rest and starting from the at-rest speed value, increasing the speed of the electric machine (3) when there is a demand to engage a gear in the transmission device (6), starting from a neutral operating condition during which a force flow of the vehicle's hybrid drive train (1) is interrupted in an area of the transmission device (6).

### Claim 3 (depends on 1)

The method according to claim 1, further comprising the step of, starting from the at-rest speed value, increasing the speed of the electric machine (3) if a starting process of the vehicle is called for.

### Claim 4 (depends on 1)

The method according to claim 1, further comprising the step of, starting from the at-rest speed value, increasing the speed of the electric machine (3) if starting the internal combustion engine is called for.

### Claim 5 (depends on 1)

The method according to claim 1, further comprising the step of, when the speed of the vehicle is greater than zero, setting the speed of the electric machine (3) as a function of the torque to be transmitted by the transmission device (6).

### Claim 6

A method of operating a hybrid drive train (1) of a vehicle which comprises an internal combustion engine (2) and an electric machine (3) which are both drivably connectable with a drive output (4) of the drive train (1), a clutch device (5) arranged in the drive train (1), between the internal combustion engine (2) and the electric machine (3) such that the internal combustion engine is rotationally fixable to the electric machine, an oil pump device (7) arranged in the drive train (1) downstream of the clutch device (5) in relation to a flow of power from the internal combustion engine (2) to the drive output (4), the oil pump device (7) drivably connectable with the internal combustion engine (2) and the electric machine (3), and a transmission (6) comprises a plurality of shifting elements which are actuatable to implement various gear steps, the method comprising the steps of:
driving the oil pump device (7) with the electric machine (3) and adjusting a rotational speed of the electric machine (3) independent of a rotational speed of the internal combustion engine (2) to adjust the drive of the oil pump device (7) and a supply of oil to the transmission (6) and the plurality of shifting elements depending an oil volume flow required for a currently operating status of the drive train (1);
adjusting the rotational speed of the electric machine (3), independent of the rotational speed of the internal combustion engine (2), such that when the vehicle is approximately at rest, the rotational speed of the electric machine (3) is at an at-rest speed which is lower than an idling speed of the internal combustion engine (2), such that the oil pump device (7), driven by the electric machine (3), maintains at least partial actuation of the shifting elements in a current operating status of the transmission (6); and
increasing the rotational speed of the electric machine (3), to increase the drive of the oil pump device (7), when the vehicle is at rest and when a demand is made for at least one of a gear change from a starting gear to a higher gear step and a gear change from a higher gear step to the starting gear; and
increasing the rotational speed of the electric machine (3), from the at-rest speed, when the vehicle is at least approximately at rest, if a demand is made for disengaging a parking lock device.

### Claim 7 (depends on 6)

The method according to claim 6, further comprising the step of increasing the rotational speed of the electric machine (3) from the at-rest speed, when the vehicle is at least approximately at rest and a demand is made for a gear change in the transmission device (6) from a neutral operating condition, during which a flow of power in the hybrid drive train (1) is interrupted in the transmission device (6).

### Claim 8 (depends on 6)

The method according to claim 6, further comprising the step of increasing the rotational speed of the electric machine (3), from the at-rest speed, if a vehicle starting process is requested.

### Claim 9 (depends on 6)

The method according to claim 6, further comprising the step of increasing the rotational speed of the electric machine (3), from the at-rest speed, if starting the internal combustion engine is requested.

### Claim 10 (depends on 9)

The method according to claim 9, further comprising the step of setting the rotational speed of the electric machine (3), when the speed of the vehicle is greater than zero, as a function of torque to be transmitted by the transmission device (6).

### Claim 11

A method of operating a vehicle hybrid drive train (1) comprising an internal combustion engine (2) and an electric machine (3) whose torque is applied to a drive output (4) of the vehicle hybrid drive train (1), a clutch device (5) arranged between the internal combustion engine (2) and the electric machine (3), an oil pump device 7 arranged in the vehicle hybrid drive train (1), downstream of the clutch device (5), in relation to the internal combustion engine (2), and drivable by both the internal combustion engine (2) and by the electric machine (3), and a transmission device (6) which comprises a plurality of shifting elements for producing various gear ratios and which is supplied with hydraulic fluid by the oil pump device (7) in an operating-status-dependent manner such that a speed of the electric machine (3) is set, independently of a speed of the internal combustion engine (2), in order to supply the transmission device (6), in each case, with a hydraulic fluid volume flow required for an operating point of the transmission device (6) present at the time, the method comprising the steps of:
corresponding the speed of the electric machine (3) to an at-rest speed value which is lower than an idling speed of the internal combustion engine (2), when the vehicle is at least approximately at rest, such that the oil pump device (7) driven by the electric machine (3) maintains the shifting elements in an at least partially engaged condition so as to maintain a current operating status of the transmission device (6),
increasing the speed of the electric machine (3), in a range when the vehicle is at rest, when there is at least one of a shift demand for a gear change from a starting gear to a higher gear step and a shift demand for a gear change from a higher gear step to a starting gear, and
when the vehicle is at least approximately at rest and starting from the at-rest speed value, increasing the speed of the electric machine (3) if there is a demand for disengaging a parking lock device.