DE102014204447A1 - Engine operation method and motor vehicle - Google Patents

Abstract

An engine operating method (20) is provided for operating a multi-cylinder reciprocating engine (11). The reciprocating engine (11) is configured to operate at least one of the cylinders as a standby cylinder (12) in either a load mode or a shutdown mode while simultaneously operating at least one other of the plurality of cylinders in the load mode, with a cylinder operated in load mode with fuel is supplied and a operated in the shutdown mode cylinder is not supplied with fuel. In the engine operation method (20), at least the standby cylinder (12) is operated in the shutdown mode while at least one other of the plurality of cylinders is operated in the load mode. According to the invention, in the shutdown mode, a valve (13, 14) of the standby cylinder (12) is opened with a smaller maximum stroke (28) than a maximum stroke (26) with which the valve (13, 14) of the standby cylinder (12) is opened in load mode. In addition, a motor vehicle (10) with a reciprocating engine (11) is claimed.

Description

The present invention relates to an engine operating method for operating a multi-cylinder reciprocating engine having a cylinder deactivation. In addition, the present invention relates to a motor vehicle which is designed to exercise the engine operating method.

In reciprocating engines with multiple cylinders, it is known to operate a so-called cylinder shutdown to reduce fuel consumption and emissions. In this case, individual cylinders of the reciprocating engine are switched off in that they are not supplied with fuel.

The DE 10 2005 010 673 A1 shows a method for operating a multi-cylinder internal combustion engine, by means of which, starting from an idle, a considerably shortened response of an internal combustion engine to a load request is to be ensured. For this purpose, during idling operation in a multi-cylinder internal combustion engine, a first group of cylinders is fired and a second group of cylinders operated unfired. The valve drive may be partially or fully variable, with variable timing and / or variable valve lifts for inlet and / or outlet valve, be formed. A fully variable valve train is used, which is variable both in terms of timing and in terms of its valve lift.

Also the US 5271229 A deals with the solution of the improved response and discloses a method and a corresponding device. The method of operating an engine having a plurality of combustion chambers, an intake passage and an exhaust passage for each of the combustion chambers, a turbocharger with a compressor of a turbine and a certain pressure level, a reciprocating piston in each of the combustion chambers comprises the steps Monitoring the operating condition of the engine, outputting a control signal to an inlet means and an outlet means, actuating each of the inlet means and the outlet means independently in response to a control signal, actuating the inlet means of a selected subset of the combustors during each inlet and expansion stroke to allow flow of air into the combustion chambers, and actuating the exhaust means of the selected subset of combustors during each compression and exhaust stroke to increase the flow of air through the turbine and increase the boost pressure level.

During a cylinder deactivation, the pistons continue to move in the cylinder. As a result of the movements of the piston, a pressure in the deactivated cylinder can arise, in particular at the bottom dead center of the piston, which pressure is lower than a pressure in the crankcase, if the valves are closed at this time. This pressure difference can lead to leaks and pull oil from the crankcase into the deactivated cylinder. This can result in undesirable operating conditions and increased emission levels in the further operation of the reciprocating engine.

The present invention has for its object to provide an engine operating method, with which the aforementioned disadvantages are eliminated and to provide a motor vehicle, which is designed to carry out the engine operating method.

This object is achieved with an engine operating method according to claim 1 and a motor vehicle according to claim 8. Advantageous developments of the invention are specified in the subclaims and described in the description.

In the engine operating method of the invention for operating a multi-cylinder reciprocating engine, at least one standby cylinder is operated in a shutdown mode while at least one other of the plurality of cylinders is operated in a load mode. The reciprocating engine is configured to operate at least one of the cylinders as a standby cylinder in either the load mode or the shutdown mode while simultaneously operating at least one other of the plurality of cylinders in the load mode. A cylinder operated in load mode is fueled and a cylinder operating in shutdown mode is not fueled. In the engine operating method according to the invention, the valve of the standby cylinder is opened in the shutdown mode with a smaller maximum stroke than a maximum stroke, with which the valve of the standby cylinder is opened in the load mode.

This advantageously makes it possible to equalize the pressure in the deactivated standby cylinder and to prevent a negative pressure from building up in the standby cylinder in the shutdown mode relative to the crankcase of the reciprocating engine and resulting in leaks.

The smaller maximum stroke is sufficient for pressure equalization in the deactivated standby cylinder and for flushing with hot exhaust gases. At the same time, less work is done with the smaller maximum stroke and the efficiency of the reciprocating engine is improved.

In an advantageous embodiment of the engine operating method according to the invention, the maximum stroke of the valve of the standby cylinder is in shutdown mode, 5 percent to 15 percent of the maximum lift of the standby cylinder valve in load mode.

The range between 5 percent to 15 percent of the maximum lift of the valve in load mode is particularly favorable.

In a further advantageous embodiment of the engine operating method according to the invention, the valve of the standby cylinder which is opened is an outlet valve.

As a result, hot exhaust gases of the cylinder operated in the load mode can reach the deactivated standby cylinder and heat it up or prevent it from cooling down on the standby cylinder.

In a further advantageous embodiment of the engine operating method according to the invention, the valve of the standby cylinder is opened in the shutdown mode for a shorter opening duration than an opening duration for which the valve of the standby cylinder is opened in the load mode. In particular, the opening duration of the valve of the standby cylinder in the shutdown mode is 15 percent to 25 percent of the opening duration of the valve of the standby cylinder in the load mode.

The shorter opening time is sufficient for pressure equalization in the deactivated standby cylinder and for flushing with hot exhaust gases. At the same time, less work is done with the shorter opening time and the efficiency of the reciprocating engine is improved. The range between 15 percent to 25 percent of the opening duration of the valve in load mode is particularly favorable.

In a further advantageous embodiment of the engine operating method according to the invention, the valve of the standby cylinder is opened in the shutdown mode in such a way that the valve of the standby cylinder reaches its maximum stroke at a different crank angle than the crank angle at which the valve of the standby cylinder reaches its maximum stroke in the load mode. In particular, the crank angle of the valve of the standby cylinder is 30 degrees to 90 degrees smaller than the crank angle of the valve of the standby cylinder when reaching the maximum stroke in the shutdown mode when reaching the maximum stroke in the load mode.

Due to the shifted time of the opening of the pressure compensation can take place in particular near the bottom dead center of the piston in the standby cylinder. In this piston position, the expected negative pressure would be greatest. An opening of one of the valves is thus most effective at this point of the piston and the opening duration and the maximum stroke of the valve can be reduced thereby.

The motor vehicle according to the invention has a reciprocating piston engine comprising several cylinders. In this case, the reciprocating engine is configured to operate at least one of the cylinders as a standby cylinder in either a load mode or a shutdown mode while simultaneously operating at least one other of the plurality of cylinders in load mode, fueling a cylinder operated in load mode and powering off mode operated cylinder is not supplied with fuel. The reciprocating engine also has at least one inlet valve and one outlet valve per cylinder and the reciprocating engine is designed to carry out the engine operating method according to the invention.

Thus, a motor vehicle is provided, which is favored by the advantages of the engine operating method according to the invention.

Embodiments of the invention will be explained in more detail with reference to the drawings and the description below. Show it:

1 a motor vehicle according to the invention; and

2 an engine operating method according to the invention.

In the 1 is the motor vehicle according to the invention 10 sketched in an exemplary embodiment in a sectional view. The car 10 has according to the invention a reciprocating engine 11 with several cylinders on. In the embodiment shown, the motor vehicle has 10 via a transversely mounted in-line engine 11 with four cylinders. According to the invention, other configurations are also conceivable, for example a V arrangement of the cylinders. In each cylinder is as usual a piston 16 arranged. The piston 16 is over a connecting rod 19 with one in a crankcase 18 stored crankshaft 17 connected. Controlled or regulated is the reciprocating engine 11 from an engine control unit 15 ,

The reciprocating engine 11 According to the invention, each cylinder has at least one inlet valve 13 and an exhaust valve 14 on. The valves 13 . 14 are preferred by one with the crankshaft 17 controlled in operative connection camshaft, as it is widely used.

The reciprocating engine 11 is preferably a four-stroke engine. The reciprocating engine 11 is formed according to the invention, at least one of the cylinders as a standby cylinder 12 either in one Operate load mode or in a shutdown mode, while at the same time at least another of the plurality of cylinders is operated in the load mode. Load mode here means that the cylinder operated in load mode is supplied with fuel in the corresponding power stroke. Shutdown mode here means that the cylinder operated in the shutdown mode is not supplied with fuel in the corresponding power stroke. Has the reciprocating engine 11 as a four-stroke engine via a port injection, the corresponding power stroke is the intake stroke, has the reciprocating engine 11 via a direct injection, the corresponding power stroke can also be the compression stroke.

The non-supply of cylinders with fuel is known as so-called cylinder deactivation. The reciprocating engine 11 has such a cylinder deactivation. The reciprocating engine 11 includes corresponding devices for performing the cylinder deactivation. For example, the camshaft of the reciprocating engine 11 be slidable, so the valves 13 . 14 depending on the modes with different cams in operative connection. It is also conceivable according to the invention that the valves 13 . 14 be controlled electro-hydraulically.

In conventional Zylinderabschaltsystemen remain the valves 13 . 14 completely closed in shutdown mode. By the movement of the piston 16 In the cylinder, this can result in a pressure in the cylinder, which is lower than the prevailing pressure in the crankcase 18 , This can cause leakage and oil from the crankcase 18 be pulled into the cylinder. In addition, a cylinder shutdown according to conventional manner can adversely affect the thermal situation of the reciprocating engine and cool down the cylinder located in the off mode unintentionally strong. The reciprocating piston engine according to the invention 11 prevents these phenomena in that it is formed, an engine operating method according to the invention 20 perform.

The engine operating method according to the invention 20 is to operate the reciprocating engine 11 suitable. According to the invention, the engine operating method 20 in shutdown mode, a valve 13 . 14 of the standby cylinder 12 open.

The engine operating method according to the invention 20 is in the 2 illustrated in an exemplary embodiment. A vertical axis of the diagram indicates a valve lift 21 in millimeters and a horizontal axis of the graph gives a crank angle 22 the crankshaft 17 in degrees.

In the engine operating method according to the invention 20 will at least be the standby cylinder 12 operated in the shutdown mode, while at least one other of the cylinders is operated in load mode. In the 2 are the valve lift curves 23 . 24 . 25 of the inlet valve 13 and the exhaust valve 14 of the standby cylinder 12 mapped in both modes. In load mode, the exhaust valve points 14 an exhaust valve lift stroke 23 and the intake valve has an intake valve lift course 24 on.

The outlet valve 14 reaches a Auslassventillastmaximalhub in load mode in the embodiment shown 26 between 7 mm and 8 mm at a crank angle 22 from about 240 degrees. The outlet valve 14 is here in a range of the crank angle 22 from about 120 degrees to about 400 degrees. The outlet valve 14 is thus opened in load mode via a crank angle change of about 280 degrees.

The inlet valve 13 reaches an intake valve load maximum lift in load mode in the embodiment shown 27 between 7 mm and 8 mm at a crank angle 22 from about 460 degrees. The inlet valve 13 is here in a range of the crank angle 22 from about 330 degrees to about 610 degrees. The inlet valve 13 is thus opened in load mode via a crank angle change of about 280 degrees.

According to the invention, in the shutdown mode, the inlet valve 13 or the outlet valve 14 be opened. In the embodiment of the engine operating method shown 20 becomes the exhaust valve 14 opened in shutdown mode. 2 shows a Auslassventilabschalthubverlauf 25 the exhaust valve 14 in shutdown mode. The outlet valve 14 reaches a Auslaßventilabschaltmaximalhub in the illustrated embodiment in the shutdown mode 28 between 5 mm and 9 mm at a crank angle 22 from about 180 degrees. The outlet valve 14 is here in a range of the crank angle 22 open from about 150 degrees to about 210 degrees. The outlet valve 14 is thus opened in the shutdown mode via a crank angle change of about 60 degrees. Compared to the load mode here is the exhaust valve 14 opened in shutdown mode later, it opens shorter and it is less open.

Would the inlet valve 13 In the shutdown mode, an intake valve shutoff stroke would be in the same proportion to the intake valve lift stroke 24 as in the embodiment shown, the Auslassventilabschalthubverlauf 25 to Auslassventillasthubverlauf 23 stands.

LIST OF REFERENCE NUMBERS

10

 motor vehicle

11

 reciprocating engine

12

 willingness cylinder

13

 intake valve

14

 outlet valve

15

 Engine control unit

16

 piston

17

 crankshaft

18

 crankcase

19

 pleuel

20

 Engine operating procedures

21

 valve

22

 crank angle

23

 Auslassventillasthubverlauf

24

 Einlassventillasthubverlauf

25

 Auslassventilabschalthubverlauf

26

 Auslassventillastmaximalhub

27

 Einlassventillastmaximalhub

28

 Auslassventilabschaltmaximalhub

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005010673 A1 [0003]
• US 5271229 A [0004]

Claims (8)

Engine operating method ( 20 ) for operating a multi-cylinder reciprocating engine ( 11 ), which is formed, at least one of the cylinders as a standby cylinder ( 12 ) operate in either a load mode or a shutdown mode while simultaneously operating at least one other of the plurality of cylinders in load mode, fueling a cylinder operated in load mode and not fueling a cylinder operating in shutdown mode, at least the standby cylinder ( 12 ) is operated in the shutdown mode, while at least one other of the plurality of cylinders is operated in the load mode, characterized in that in the shutdown mode, a valve ( 13 . 14 ) of the standby cylinder ( 12 ) with a smaller maximum stroke ( 28 ) is opened as a maximum lift ( 26 ), with which the valve ( 13 . 14 ) of the standby cylinder ( 12 ) is opened in load mode. Engine operating method ( 20 ) according to claim 1, wherein the maximum stroke ( 28 ) of the valve ( 13 . 14 ) of the standby cylinder ( 12 ) in the shutdown mode 5 percent to 15 percent of the maximum lift ( 26 ) of the valve ( 13 . 14 ) of the standby cylinder ( 12 ) in load mode. Engine operating method ( 20 ) according to claim 1 or 2, wherein the valve ( 13 . 14 ) of the standby cylinder ( 12 ), which is opened, an exhaust valve ( 14 ). Engine operating method ( 20 ) according to one of claims 1 to 3, wherein the valve ( 13 . 14 ) of the standby cylinder ( 12 ) is opened in shutdown mode for a shorter opening duration than an opening duration for which the valve ( 13 . 14 ) of the standby cylinder ( 12 ) is opened in load mode. Engine operating method ( 20 ) according to claim 4, wherein the opening duration of the valve ( 13 . 14 ) of the standby cylinder ( 12 ) in shutdown mode, 15 percent to 25 percent of the opening time of the valve ( 13 . 14 ) of the standby cylinder ( 12 ) in load mode. Engine operating method ( 20 ) according to one of claims 1 to 5, wherein the valve ( 13 . 14 ) of the standby cylinder ( 12 ) is opened in shutdown mode in such a way that the valve ( 13 . 14 ) of the standby cylinder ( 12 ) its maximum stroke ( 28 ) at a different crank angle ( 22 ) reached as the crank angle ( 22 ), in which the valve ( 13 . 14 ) of the standby cylinder ( 12 ) its maximum stroke ( 26 ) in load mode. Engine operating method ( 20 ) according to claim 6, wherein the crank angle ( 22 ) of the valve ( 13 . 14 ) of the standby cylinder ( 12 ) when reaching the maximum lift ( 28 ) in shutdown mode is 30 degrees to 90 degrees less than the crank angle ( 22 ) of the valve ( 13 . 14 ) of the standby cylinder ( 12 ) when reaching the maximum lift ( 26 ) in load mode. Motor vehicle ( 10 ) with a multi-cylinder reciprocating engine ( 11 ), which is formed, at least one of the cylinders as a standby cylinder ( 12 ) operate in either a load mode or a shutdown mode while simultaneously operating at least one other of the plurality of cylinders in load mode, fueling a cylinder operated in load mode and not fueling a cylinder operating in shutdown mode, the reciprocating engine ( 11 ) at least one inlet valve per cylinder ( 13 ) and an outlet valve ( 14 ) and the reciprocating engine ( 11 ), the engine operating method ( 20 ) according to one of the preceding claims.

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