DE102018128526A1 - Actuators for variable adjustment of the compression in an internal combustion engine - Google Patents

Abstract

The invention relates to an actuator system for variably adjusting the compression in an internal combustion engine with an adjusting shaft (2) which can be driven in rotation and which is at least partially surrounded by a housing (1), characterized in that, in order to limit the adjusting range, the adjusting shaft (2) turns in the direction of rotation an end stop (5) arranged for hydraulic stop damping in an oil sump (3) can be placed on the housing (1).

Description

Field of the Invention

The invention relates to an actuator for variable adjustment of the compression in an internal combustion engine according to the kind defined in the preamble of claim 1.

Out DE 10 2014 112 689 A1 an arrangement for adjusting the rotational position of an adjusting shaft is known. The adjusting shaft is designed as an eccentric shaft, via which the expansion stroke and the compression ratio can be adjusted in an internal combustion engine with a multi-joint crank drive. For the adjustment, an adjustment shaft is rotated and the adjustment movement is transmitted via an adjustment connecting rod and an adjustment lever which is articulated to the adjustment connecting rod.

Furthermore, in US8726858 , EP2787196 and DE 102008060932 Actuators for adjusting a control or eccentric shaft are described, which are used to adjust the compression ratio of an internal combustion engine. The adjustment range of the actuator or the adjustment shaft is limited for technical, in particular thermodynamic reasons. This limitation is usually achieved by stops in the adjustment path. In the event of a malfunction of an electric motor of the actuator, for example, the plug falling off, loss of the signal, etc., it is possible for the electric motor to drive the adjusting shaft to the end stop at a high speed in an uncontrolled manner. Due to the inertia of the rapidly rotating components, especially on the electric motor, a high moment arises at the end stop. Depending on the design, this moment can exceed the permissible voltage of the actuator, in particular of a housing thereof.

Summary of the invention

The invention is therefore based on the object of reducing the loads on an end stop in order to limit the adjustment range in the case of actuators of the aforementioned type.

The object is achieved by the features of patent claim 1. Further advantageous configurations result from the description and the drawings.

An actuator system for variable adjustment of the compression in an internal combustion engine is proposed. The actuator system has an adjusting shaft which can be driven in rotation and which is at least partially surrounded by a housing. According to the invention, in order to limit the adjustment range of the actuator system, the adjustment shaft can be placed in the direction of rotation on an end stop arranged on the housing for hydraulic stop damping in an oil sump. In this way, hydraulic stop damping is achieved in the oil sump. The speed of the rapidly rotating components of the actuator system before the contact at the end stop is reduced by the hydraulic damping in the oil in the oil sump, thus significantly reducing the resulting stop torque. Alternatively, the oil sump can serve as an oil reservoir for a hydraulic spring stop element in the housing-side stop. For hydraulic stop damping, existing lubrication devices of the actuators, in particular the oil supply, can be used to generate an oil sump in the area of the end stop. It is also possible to arrange the end stop in an already existing oil sump in the housing.

Figure list

• 1 eine Schnittdarstellung einer erfindungsgemäßen Aktorik zur variablen Einstellung der Kompression in einer Brennkraftmaschine in einem ersten Ausführungsbeispiel,
• 2 einen vergrößerten Ausschnitt aus 1,
• 3 eine Schnittdarstellung aus 2,
• 4 eine geschnittene Teilansicht einer erfindungsgemäßen Aktorik in einem zweiten Ausführungsbeispiel.

Further features of the invention result from the following description and from the drawings, in which several exemplary embodiments of the invention are shown in simplified form. Show it:

• 1 1 shows a sectional illustration of an actuator system according to the invention for variable adjustment of the compression in an internal combustion engine in a first exemplary embodiment,
• 2nd an enlarged section 1 ,
• 3rd a sectional view 2nd ,
• 4th a partial sectional view of an actuator according to the invention in a second embodiment.

Detailed description of the drawings

1 shows a sectional view of an actuator according to the invention for variable adjustment of the compression in an internal combustion engine. The actuator system has one in a housing 1 rotatable adjustment shaft 2nd on, partially in an oil sump indicated by an oil level P. 3rd immersed. The adjustment shaft 2nd is on the outside diameter with a radial projection 4th with a flat stop surface aligned in the direction of rotation 6 executed. The lead 4th is with the stop surface 6 to limit the adjustment range of the actuator system when it rotates on a corresponding counter-stop surface 7 an end stop 5 on the housing 1 can be created. The end stop 5 is in the oil sump 3rd arranged in the direction of gravity below the oil level P and is, for example, by a projection or shoulder on the inner wall of the housing 1 educated. Because the end stop 5 on the housing 1 , in the area of the oil sump 3rd is below the oil level P, the protrusion 4th on the adjustment shaft 2nd upon rotation of the same to stop on the housing-side end stop 5 in the oil sump immerse. This will prevent the tab from contacting 4th with the end stop on the housing side 5 the adjusting shaft 2nd slowed down by the friction of the oil displaced at the latter, which is indicated by an arrow. This is the rotational energy of the adjusting shaft 2nd reduced and the resulting torque before striking the housing-side end stop 5 subdued. The damping can be achieved through the oil level P in the housing 1 be set accordingly. The existing lubricating oil supply to the actuator system can be used for this. In this way, a simple hydraulic stop damping in the oil sump 3rd of the housing 1 reached.

To increase the damping effect, according to 2nd and 3rd at the end stop 5 in the housing 1 additionally a recess or groove 8th be provided. This extends in the direction of rotation of the adjusting shaft 2nd and forms the counter stop surface at its end 7 . In this way, the lead dives 4th the adjusting shaft 2nd when striking the end stop 5 into the recess or groove 8th a. Here are these and the lead 4th on the outside diameter of the adjusting shaft 2nd executed such that when the projection is immersed 4th into the recess or groove 8th a small gap between this and the latter S in the housing 1 through which the oil, as indicated by arrows, rotates the adjusting shaft further 2nd to stop at the end stop 5 must be pressed out. The viscous friction is increased and additional stroke damping is achieved.

Another version of a hydraulic stop damping is in 4th shown. Here is the end stop on the housing side 5 a hydraulic spring stop element 9 provided that is similar to a hydraulic tappet or hydraulic shock absorber. The spring stop element 9 is at the end stop 5 for example in a hole 10th on the housing 1 , here a blind hole, pressed or clipped in the form of a cartridge. It consists of one in the hole 10th slidably guided piston 11 , the counter-stop surface at one end in the direction of displacement 7 forms and at the other end with a T-shaped spring support in the longitudinal profile 12th is executed, which is a flat spring support surface 13 forms. One in the hole 10th led spring 14 , for example a helical compression spring, is at one end on the spring support surface 13 and with the other end at the inner end of the hole 10th supported. The piston is at its stop end 11 tapered on the outer diameter, being between this and the inner diameter of the bore 10th a ring 14 , is arranged, the piston 11 against falling out of the hole 10th backs up.

By deliberately setting an oil sump with the oil level P such that the area of the end stop 5 in the housing 1 covered with oil and below the oil level P in the direction of gravity, the hole fills up 10th with the hydraulic spring stop element 9 with oil. In the event of a stop, the contact of the projection 4th the adjusting shaft 2nd with the piston 11 at the end stop on the housing side 5 against the feather 14 in the hole 10th pressed. The oil passes through a small gap S between the outside diameter of the piston 10th and the inside diameter of the hole 10th pressed out and thereby reducing the impact energy.

The adjustment shaft 2nd is connected via a drive connection (not shown), for example a wave gear, to an actuator, in particular an electric motor, for transmitting an adjusting torque. The adjustment shaft 2nd is designed as an eccentric shaft to which an adjusting connection, in particular with an articulated connecting rod, can be connected via an eccentric bolt. About this is through the adjustment shaft 2nd the compression or compression of the internal combustion engine is variably adjustable.

Reference symbol list

1

casing

2nd

Adjustment shaft

3rd

Oil sump

4th

head Start

5

End stop

6

Abutment surface

7

Counter stop surface

8th

Recess, groove

9

Spring stop element

10th

drilling

11

piston

12

Spring support

13

Spring support surface

14

feather

S

gap

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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.

Patent literature cited

• DE 102014112689 A1 [0002]
• US 8726858 [0003]
• EP 2787196 [0003]
• DE 102008060932 [0003]

Claims (1)

Actuator for variable adjustment of the compression in an internal combustion engine with a rotationally drivable adjusting shaft (2), which is at least partially surrounded by a housing (1), characterized in that to limit the adjusting range, the adjusting shaft (2) in the direction of rotation on one for hydraulic stop damping in an oil sump (3) arranged end stop (5) on the housing (1) can be applied.

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