WO2018166581A1

WO2018166581A1 - On-demand purge pump system

Info

Publication number: WO2018166581A1
Application number: PCT/EP2017/055910
Authority: WO
Inventors: Ingo Geue; Florian Weigt; Jens Hunecke; Dominik NIESS; Thorsten SCHULTE
Original assignee: HELLA GmbH & Co. KGaA
Priority date: 2017-03-14
Filing date: 2017-03-14
Publication date: 2018-09-20

Abstract

The invention relates to a purge pump system (1) of a vehicle (2) for purging C-H-gas of a tank system (3) to an induction line (4) of a combustion engine (5) of the vehicle (2), comprising a purge pump (6) and gas connection lines (7) for connecting the purge pump (6) with the tank system (3) and the induction line (4), wherein the purge pump system (1) further comprises a motor (8) for driving the purge pump (6) and a control unit (9) for operating the motor (8). The control unit (9) is configured for operating the motor (8) with frequently changing rotational speeds. The invention further relates to a vehicle (2) and a method for operating a purge pump system (1) of a vehicle (2) according to the invention.

Description

On-Demand Purge Pump System

Description

The invention relates to an on-demand purge pump system of a vehicle for purging C- H-gas of a tank system to an induction line of a combustion engine of the vehicle. Moreover, the invention relates to a vehicle with such purge pump system and a method for operating a purge pump system of a vehicle.

Vehicles with a combustion engine comprise a tank system for storing liquid fuel. For such fuel tank systems, evaporation of hydrocarbon gas within the tank system is an issue. By means of an activated carbon filter, evaporated hydrocarbon gas of the tank system is bound. The tank system further comprises a duct line, for forwarding the hydrocarbons to an induction line for providing the combustion engine with filtered oxygen mixed with the hydrocarbons. Generally, the transport of the hydrocarbons from the active carbon filter to the combustion engine is evoked by a negative pressure within the induction line. For controlling a volumetric flow of the

hydrocarbons, a purge valve is provided between the induction line and the active carbon filter.

In some cases, the negative pressure of the induction line is not big enough for assuring a predetermined volumetric flow of the hydrocarbons. In order to overcome this drawback, a purge pump is provided between the active carbon filter and the purge valve. The purge pump is configured for the suction of fresh air via a separate air duct line through the active carbon filter, wherein, by these means, the fresh air is mixed with the hydrocarbons within the active carbon filter. The purge pump is further configured for the transport of the hydrocarbon-air-mixture to the induction line of the combustion engine. The purge pump is configured as a continuously operating pump, forwarding the hydrocarbon-air-mixture with a constant or at least substantially constant volumetric flow. In this case, the volumetric flow is still controlled by the purge valve. This has the advantage that a tank system architecture without such purge pump just needs minor adjustment for the integration of a purge pump. For ensuring a reliable continuous operation of the purge pump, standard purge pumps are operated by a brushless DC motor.

However, conventional purge pump systems have the substantial drawback that energy consumption and CO2 emissions are relatively high due to the purge pump that operates continuously.

It is therefore an object of the present invention, to provide a purge pump system, a vehicle and a method for operating a purge pump system of a vehicle that overcome or at least improve the drawbacks mentioned above. In particular, it is an object of the present invention, to provide a purge pump system, a vehicle and a method for operating a purge pump system of a vehicle that show less energy consumption and/or less CO2 emissions than state in the art solutions.

This object is solved by the patent claims. In particular, this object is solved by a purge pump system according to independent claim 1 , a vehicle with a combustion engine according to independent claim 9 and a method for operating a purge pump system of a vehicle according to independent claim 10. Further features and details of the invention are comprised in the dependent claims, the description and the drawings. In this context, features and details being described with respect to the inventive purge pump system are certainly valid for the inventive vehicle as well as the inventive method and the other way round. Therefore, with respect to the disclosure, reference can and will be made mutually between the different aspects of the invention.

According to a first aspect of the invention, the object is solved by a purge pump system of a vehicle for purging C-H-gas of a tank system to an induction line of a combustion engine of the vehicle. The purge pump system comprises a purge pump and gas connection lines for connecting the purge pump with the tank system and the induction line. The purge pump system further comprises a motor for driving the purge pump and a control unit for operating the motor. According to the invention, the control unit is configured to operate the motor with frequently changing rotational speeds, wherein the motor is configured for being operated with frequently changing rotational speeds.

A pump inlet of the purge pump is connected to the tank system, especially to the tank of the vehicle, by a first gas connection line. Thus, C-H-gas of the tank can be sucked into the purge pump. Preferably, the tank system comprises an active carbon filter for binding the C-H-gas of the tank. The active carbon filter is preferably interconnected in between the tank and the pump inlet via the first gas connection line. Furthermore, it is preferred that the tank system comprises an air inlet with an air filter and an air duct for connecting the air filter with the active carbon filter. Thus, filtered air can be mixed with the C-H-gas and sucked into the purge pump. A pump outlet of the purge pump is connected via a second gas connection line to the induction line of the combustion engine of the vehicle.

The purge pump comprises a motor for driving the purge pump, e.g. a pump unit of the purge pump to pump fluid from the first gas connection line to the second gas connection line. By these means, C-H-gas from the active carbon filter can be pumped towards the induction line. A rotational speed of the motor is proportional to a volume flow of pumped C-H-gas.

For operating the motor, the purge pump system comprises a control unit. The control unit is configured for providing and/or generating a current for effecting the relative rotation of a rotor of the motor to a stator of the motor. By means of the control unit, the motor can be operated at frequently changing rotational speeds. Since the volume flow of the pumped C-H-gas is proportional to the rotational speed of the motor, by controlling the rotational speed of the motor, the volume flow can be controlled.

Preferably, to reduce a delay between setting a target rotational speed of the motor by the control unit and achieving the target rotational speed by the motor, the motor shows a high dynamical characteristic, e.g. the motor is configured for acceleration from idleness to 90% of its maximum rotational speed within less than 1 second, preferably less than 0.8 seconds. Such motor has the advantage that control of the volume flow of the C-H-gas is improved.

The purge pump system of the invention has the advantage that due to the possibility of operating the motor of the purge pump with frequently changing rotational speeds, a volume flow of the C-H-gas through the purge pump can be easily controlled by controlling the rotational speed of the motor. By these means, the motor can be operated on demand instead of being operated continuously. Thus, energy

consumption and CO2 emissions are reduced significantly.

According to a preferred embodiment of the invention, the motor is a brushless DC motor. Preferably, the control unit is configured to generate the commutative current for operating the motor. A brushless DC motor has the advantage of high reliability, less inner friction and low energy consumption. Thus, energy consumption and CO2 emissions can be further reduced. Moreover, due to the high reliability of the brushless DC motor, maintenance intervals of the purge pump system can be extended and, thus, maintenance costs can be reduced.

It is preferred that the motor is configured for acceleration from idleness to 90% of its maximum rotational speed within less than 0.5 seconds. Such motor has a very high dynamical characteristic. A motor with a very high dynamical characteristic has the advantage that a target rotational speed, set by the control unit, is faster achievable than with a motor that has a weaker dynamical characteristic. Hence, with such motor, the volume flow of C-H-gas through the purge pump can be controlled with an improved accuracy.

It is further preferred that the purge pump system further comprises a check valve for preventing a fluid volume flow from the induction line towards the purge pump. The check valve is preferably a passive valve that blocks fluid volume flow from the induction line towards the purge pump and allows fluid volume flow from the purge pump towards the induction line. Preferably, the check valve is located at a gas connection line between the induction line and the purge pump. A check valve has the advantage, that a back volume flow of explosive gas in a direction from the induction line towards the tank system is prevented. Thus, the operation reliability and efficiency of the purge pump system is increased, while energy consumption and CO2 emissions can be further reduced.

Preferably, the purge pump system does not comprise a purge valve that is arranged between the tank system, the purge pump and the induction line. A purge valve is a valve that is configured for controlling a fluid volume flow through the gas connection lines. Since the purge pump is configured for controlling the fluid volume flow through the gas connection lines, an additional purge valve is not necessary. By these means, manufacturing costs of the purge pump system can be reduced.

According to a preferred embodiment of the invention, the purge pump system comprises a purge valve, wherein the purge valve is arranged between the induction line and the purge pump, wherein the purge valve is configured for controlling a fluid volume flow through the gas connection lines. In this configuration, it is preferred, that the purge valve is arranged at a gas connection line between the purge pump and the check valve. This configuration allows a suspension of the purge pump in case a negative pressure within the induction line is big enough for purging C-H-gas from the purge system. Moreover, in case of a purge pump failure, the function of the purge pump systems can still be fulfilled within acceptable limits. Thus, the purge pump system can be operated in an efficient and robust manner. By these means, energy consumption and CO2 emissions of the purge pump system can be further reduced.

It is further preferred that the control unit is configured to operate the motor and the purge valve. The motor can be operated by the control unit by controlling the rotational speed of the motor. Thus, the C-H-gas volume flow through the purge pump can be controlled. The purge valve can be operated by the control unit by controlling a fluid canal cross section size of the purge valve. Thus, the C-H-gas volume flow through the purge valve can be controlled. A control unit that is configured for controlling the motor and the purge valve has the advantage that a control of the C-H-gas volume flow is improved. Furthermore, since the control unit controls the motor and the purge valve, no additional sensors for determining a volume flow are necessary.

Preferably, the purge pump system comprises a converter unit for receiving a purge valve control signal of the vehicle and for converting the purge valve control signal into a motor control signal for controlling the rotation speed of the motor. The converter unit can be part of the control unit. A purge valve control signal of the vehicle is a signal that can be used to operate a purge valve of an ordinary purge system. Hence, from the purge valve control signal an intended C-H-gas volume flow can be determined by the converter unit. The converter unit is further configured to generate the motor control signal based on the intended C-H-gas volume flow. A converter unit has the advantage, that the purge pump system can be easily integrated in a vehicle architecture that has been designed for a purge system comprising a purge valve and no purge pump. Therefore, no substantial modifications have to be made. By these means, development and production costs for vehicles can be further reduced.

According to a second aspect of the invention, the problem is solved by a vehicle with a combustion engine, a tank system for providing the combustion engine with fuel and an induction line for providing the combustion engine with oxygen. The vehicle comprises a purge pump system according to the invention.

The vehicle has the same advantages over the prior art as previously described with regard to the purge pump system according to the first aspect of the invention. Hence, the vehicle has the advantage that due to the possibility of operating the motor of the purge pump with frequently changing rotational speeds, a volume flow of the C-H-gas through the purge pump can be easily controlled by controlling the rotational speed of the motor. By these means, the motor can be operated on demand instead of being operated continuously. Thus, energy consumption and CO2 emissions are reduced significantly. According to a third aspect of the invention, the problem is solved by a method for operating a purge pump system of a vehicle according to the invention. The method comprises the following steps:

- receiving a purge valve control signal of the vehicle by the converter unit;

- converting by the converter unit the purge valve control signal into a motor control signal for controlling the rotation speed of the motor of the purge pump; and

- operating the motor by the control unit based on the motor control signal.

The purge valve control signal is generated by the vehicle, e.g. by an engine control unit. The purge valve control signal is representing a desired C-H-gas volume flow from the tank system to the induction line. The converter unit is configured for receiving the purge valve control signal and for generating the motor control signal for controlling the rotation speed of the motor of the purge pump. This conversion is preferably done in a way that the desired C-H-gas volume flow is the same for the purge valve control signal and for the motor control signal. It can be intended that a pressure of the tank system and/or the induction line is considered for the conversion as well. By these means, the motor is operated in a way that the control of C-H-gas volume flow of the purge valve can be substituted by the purge pump.

The method according to the invention has the same advantages over the prior art as previously described with regard to the purge pump system according to the first aspect of the invention and the vehicle according to the second aspect of the invention. Hence, the method has the advantage that due to the possibility of operating the motor of the purge pump with frequently changing rotational speeds, a volume flow of the C-H-gas through the purge pump can be easily controlled by controlling the rotational speed of the motor. By these means, the motor can be operated on demand instead of being operated continuously. Thus, energy

consumption and CO2 emissions are reduced significantly.

In the following, preferred embodiments of the invention are described on the basis of supportive figures. In the figures, Fig. 1 schematically shows a preferred embodiment of a vehicle according to the invention in a top view;

Fig. 2 schematically shows a preferred embodiment of a purge pump system according to the invention; and

Fig. 3 schematically shows a flow chart of the method according to the invention.

In Fig. 1 , a preferred embodiment of a vehicle 2 according to the invention is schematically illustrated in a top view. The vehicle 2 comprises a combustion engine system 17. The combustion engine system 17 comprises a tank system 3 with a fuel tank 15 and an active carbon filter 1 6 for binding C-H-gas evading from the tank 15. An air filter 14 of the combustion engine system 17 is connected with the active carbon filter 1 6 for providing filtered air. The active carbon filter 1 6 is connected via a gas connection line 7 of the combustion engine system 17 with a purge pump system 1 of the combustion engine system 17. In this figure, gas connection lines 7 with a purge pump 6, a purge valve 12 and a check valve 10 of the purge pump system 1 are illustrated. The purge pump system 1 is connected via the gas connection line 7 with an induction line 4 of the combustion engine system 17. One end of the induction line 4 is connected with an air filter 14 for providing filtered air to the induction line 4.

Another end of the induction line 4 is connected to a combustion engine 5 of the combustion engine system 17.

In Fig. 2, a preferred embodiment of a purge pump system 1 according to the invention is schematically illustrated. The purge pump system 1 comprises a purge pump 6 for pumping C-H-gas from a not shown tank system 3 (c.f. Fig. 1 ) via a gas connection line 7 and a check valve 10 of the purge pump system 1 to a not shown induction line 4 (c.f. Fig. 1 ) of the combustion engine system 17 (c.f. Fig. 1 ). For pumping the C-H-gas, the purge pump system 1 comprises a motor 8. The purge pump system 1 further comprises a control unit 9 for operating motor 8. According to this preferred embodiment, the purge pump system 1 a purge valve 12 is arranged at a gas connection line 7 in between the purge pump 6 and the check valve 10. The control unit 9 is further configured for operating the purge valve 12. For converting a purge valve control signal of the vehicle 2 into a motor control signal, the control unit 9 comprises a converter unit 13. According to the invention, the bypass line 1 1 and the purge valve 12 can be omitted.

In Fig. 3, a method according to the invention is illustrated in a flow chart. In a first step 100, a purge valve control signal of the vehicle 2 is received by the converter unit 13. In a second step 200, the purge valve control signal is converted into a motor control signal for controlling the rotation speed of the motor 8 of the purge pump 6 by the converter unit 13. The conversion is preferably performed in a way that an intended C-H-gas volume flow is the same for the purge valve control signal and the motor control signal. In a third step 300, the motor 8 is operated by the control unit 9 based on the converted motor control signal.

Reference list

1 purge pump system

2 vehicle

3 tank system

4 induction line

5 combustion engine

6 Purge pump

7 gas connection line

8 motor

9 control unit

10 check valve

12 purge valve

13 converter unit

14 air filter

15 gas tank

1 6 active carbon filter

17 combustion engine system 100 first step

200 second step

300 third step

Claims

Patent claims

1 . Purge pump system (1 ) of a vehicle (2) for purging C-H-gas of a tank system

(3) to an induction line (4) of a combustion engine (5) of the vehicle (2), comprising a purge pump (6) and gas connection lines (7) for connecting the purge pump (6) with the tank system (3) and the induction line (4), wherein the purge pump system (1 ) further comprises a motor (8) for driving the purge pump (6) and a control unit (9) for operating the motor (8),

characterized in that the control unit (9) is configured for operating the motor (8) with frequently changing rotational speeds, wherein the motor (8) is configured for being operated with frequently changing rotational speeds.

2. Purge pump system (1 ) according to claim 1 ,

characterized in that the motor (8) is a brushless DC motor (8).

3. Purge pump system (1 ) according to claim 1 or 2,

characterized in that the motor (8) is configured for an acceleration from idleness to 90% of its maximum rotational speed within less than 0.5 seconds.

4. Purge pump system (1 ) according to any of the previous claims,

characterized in that the purge pump system (1 ) further comprises a check valve (10) for preventing a fluid flow from the induction line (4) towards the purge pump (6).

5. Purge pump system (1 ) according to any of the previous claims,

characterized in that the purge pump system (1 ) does not comprise a purge valve that is arranged between the tank system (3) and the induction line (4).

6. Purge pump system (1 ) according to any of claims 1 to 4, characterized in that the purge pump system (1 ) comprises a purge valve

(12) , wherein the purge valve (12) is arranged between the induction line (4) and the purge pump (6), wherein the purge valve (12) is configured for controlling a fluid volume flow through the gas connection lines (7).

7. Purge pump system (1 ) according to claim 6,

characterized in that the control unit (9) is configured to operate the purge valve (12).

8. Purge pump system (1 ) according to any of the previous claims,

characterized in that the purge pump system (1 ) comprises a converter unit

(13) for receiving a purge valve control signal of the vehicle (2) and for converting the purge valve control signal into a motor control signal for controlling the rotation speed of the motor (8).

9. Vehicle (2) with a combustion engine (5), a tank system (3) for providing the combustion engine (5) with fuel and an induction line (4) for providing the combustion engine (5) with oxygen,

characterized in that the vehicle (2) comprises a purge pump system (1 ) according to any of claims 1 to 8.

10. Method for operating a purge pump system (1 ) of a vehicle (2) according to any of claims 1 to 8, comprising the following steps:

- receiving a purge valve control signal of the vehicle (2) by the converter unit (13);

- converting by the converter unit (13) the purge valve control signal into a motor control signal for controlling the rotation speed of the motor (8) of the purge pump (6); and

- operating the motor (8) by the control unit (9) based on the motor control signal.