Variable valve train

Patent metadata

Field	Value
Publication number	US-10890087-B2
Application number	US-201816016188-A
Country	US
Kind code	B2
Filing date	Jun 22, 2018
Priority date	Jun 29, 2017
Publication date	Jan 12, 2021
Grant date	Jan 12, 2021

Abstract

The disclosure concerns a variable valve train for an internal combustion engine, comprising a camshaft, a gas exchange valve and a cam carrier. The cam carrier is arranged rotationally fixedly and axially displaceably on the camshaft and has a first cam and a second cam. The variable valve train has a force transmission device with a force transmission element, in particular a finger follower or rocker arm, which, depending on an axial position of the cam carrier, creates an active connection either between the first cam and the gas exchange valve or between the second cam and the gas exchange valve. The variable valve train has a first actuator for axial displacement of the cam carrier, wherein the first actuator is received at least partially in the force transmission device.

First claim

We claim:

1. A variable valve train for an internal combustion engine, comprising:
a camshaft;
a gas exchange valve;
a cam carrier which is arranged rotationally fixedly and axially displaceably on the camshaft and has a first cam and a second cam;
a force transmission device with a force transmission element, which, depending on an axial position of the cam carrier, creates an active connection either between the first cam and the gas exchange valve or between the second cam and the gas exchange valve; and
a first actuator for axial displacement of the cam carrier, wherein the first actuator is received at least partially in the force transmission device;
furthermore comprising a control fluid supply device for the first actuator, and including:
a bearing block which mounts the camshaft rotatably and has a first control fluid supply channel and a second control fluid supply channel arranged downstream of the first control fluid supply channel,
wherein the first control fluid supply channel and the second control fluid supply channel can be brought selectively into fluidic connection depending on a rotary angle of the camshaft via a channel.

2. The variable valve train according to claim 1 , wherein:
the force transmission device has a lever shaft, and
the first actuator is received at least partially in the lever shaft.

3. The variable valve train according to claim 2 , wherein the lever shaft is a rocker arm shaft or a finger follower shaft.

4. The variable valve train according to claim 1 , wherein:
the force transmission device has a lever shaft bearing block, and
the first actuator is received at least partially in the lever shaft bearing block.

5. The variable valve train according to claim 1 , wherein:
the first actuator is received at least partially in the force transmission element.

6. The variable valve train according to claim 1 , wherein:
the first actuator is electromagnetically, pneumatically or hydraulically actuated; and
a control line for actuating the first actuator is received at least partially in the force transmission device.

7. The variable valve train according to claim 1 , wherein the first actuator comprises:
an extendable and retractable pin which can be brought into engagement with a first engagement track extending around longitudinal axis of the camshaft, for axial displacement of the camshaft.

8. The variable valve train according to claim 7 , wherein the first actuator comprises a lift device with a first cylinder and a control piston which is arranged movably in the first cylinder, wherein the control piston is actively connected with or formed integrally with the pin.

9. The variable valve train according to claim 8 , wherein:
the lift device is arranged movably in a second cylinder of the first actuator.

10. The variable valve train according to claim 9 , wherein:
a push-out ramp is arranged at one end of the first engagement track and, when the pin leaves the track, the push-out ramp moves the lift device in the second cylinder from a first position to a second position in a direction opposite the cam carrier.

11. The variable valve train according to claim 10 , wherein a first elastic element pretensions the lift device in a direction towards the first position.

12. The variable valve train according to claim 10 , wherein the first actuator furthermore comprises:
a control fluid supply channel which, in the first position of the lift device, is fluidically connected to a control fluid chamber of the lift device; or
a control fluid discharge channel which, in the second position of the lift device, is fluidically connected to a control fluid chamber of the lift device.

13. The variable valve train according to claim 8 , wherein the first actuator furthermore comprises:
a second elastic element which pretensions the control piston in a direction opposite the cam carrier.

14. The variable valve train according to claim 8 , wherein the lift device is a hydraulic lift device.

15. The variable valve train according to claim 1 , furthermore comprising a second actuator for axial displacement of the cam carrier, wherein:
the second actuator is at least partially received in the force transmission device; or
the second actuator is configured like same as the first actuator.

16. The variable valve train according to claim 1 , wherein the channel is a transverse channel of the camshaft.

17. The variable valve train according to claim 1 , wherein the force transmission element is a finger follower or a rocker arm.

18. A motor vehicle comprising:
an internal combustion engine; and
a variable valve train including,
a camshaft;
a gas exchange valve;
a cam carrier which is arranged rotationally fixedly and axially displaceably on the camshaft and has a first cam and a second cam;
a force transmission device with a force transmission element which, depending on an axial position of the cam carrier, creates an active connection either between the first cam and the gas exchange valve or between the second cam and the gas exchange valve; and
a first actuator for axial displacement of the cam carrier, wherein the first actuator is received at least partially in the force transmission device;

furthermore comprising a control fluid supply device for the first actuator, and including:
a bearing block which mounts the camshaft rotatably and has a first control fluid supply channel and a second control fluid supply channel arranged downstream of the first control fluid supply channel,
wherein the first control fluid supply channel and the second control fluid supply channel can be brought selectively into fluidic connection depending on a rotary angle of the camshaft via a channel.

19. The variable valve train according to claim 18 , furthermore comprising a second actuator for axial displacement of the cam carrier, wherein:
the second actuator is at least partially received in the force transmission device; or
the second actuator is configured the same as the first actuator.

Assignees

• Man Truck & Bus Ag

Inventors

• Hirschmann Steffen
• Dietrich Jens
• Malischewski Thomas

Classifications

• F01L1/18 Primary

  Rocking arms or levers · CPC title

• F01L13/0036

  the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction · CPC title

• F01L1/047 Primary

  Camshafts · CPC title

• F01L2013/0052

  with cams provided on an axially slidable sleeve · CPC title

• F01L13/0042 Primary

  with cams being profiled in axial and radial direction · CPC title