Valve timing control device for internal combustion engine

1. An internal combustion engine valve timing control device comprising:

a housing structured to receive a torque from a crankshaft, wherein a working chamber is defined in the housing;

a vane rotor fixed to a camshaft, and rotatably mounted in the housing, and including a vane separating the working chamber into a plurality of separated working chambers, wherein one of the housing and the vane rotor is a first rotating member, and another of the housing and the vane rotor is a second rotating member;

an accommodation hole formed in the first rotating member;

a lock member slidably mounted in the accommodation hole, and structured to be made by a hydraulic pressure to slide in a first slide direction, and including a pressure-receiving part structured to receive the hydraulic pressure from at least one of the separated working chambers;

a biasing member mounted in the accommodation hole, and structured to bias the lock member in a second slide direction;

a lock hole formed in the second rotating member, and structured to receive insertion of a tip portion of the lock member under a biasing force of the biasing member when the first rotating member and the second rotating member are in a predetermined relative rotational position;

a back pressure chamber formed in the first slide direction from a rear end portion of the lock member in the accommodation hole;

an exhaust passage formed in at least one of the first rotating member and the second rotating member, and structured to provide communication between the back pressure chamber and an outside; and

a communication passage formed in the first rotating member to communicate with the working chamber, and including a first opening, wherein:

the first opening is structured to be opened to the back pressure chamber when in a first state that the tip portion of the lock member is inserted in the lock hole, and be closed by the lock member when in a second state that the tip portion of the lock member is out of the lock hole;

a first cross-sectional area is smaller than a second cross-sectional area;

the first cross-sectional area is a smaller one of a minimum cross-sectional area of the communication passage and an open cross-sectional area of the first opening; and

the second cross-sectional area is a smaller one of a minimum cross-sectional area of the exhaust passage and an open cross-sectional area of an opening of the exhaust passage opened to the back pressure chamber.

2. The internal combustion engine valve timing control device as claimed in claim 1 , wherein the first cross-sectional area and the second cross-sectional area are set to have a ratio of the first cross-sectional area to the second cross-sectional area that is smaller than or equal to 0.18.

3. The internal combustion engine valve timing control device as claimed in claim 2 , wherein the first cross-sectional area is set larger than or equal to 1 mm 2 .

4. The internal combustion engine valve timing control device as claimed in claim 1 , wherein the first cross-sectional area is noncircular.

5. The internal combustion engine valve timing control device as claimed in claim 1 , wherein:

the lock member is structured such that the rear end portion of the lock member closes a part of the first opening of the communication passage facing the back pressure chamber when in the first state that the tip portion of the lock member is inserted in the lock hole; and

the first cross-sectional area is of the first opening of the communication passage.

6. The internal combustion engine valve timing control device as claimed in claim 1 , wherein:

the first rotating member is the vane rotor;

the communication passage includes a second opening opened to the working chamber; and

the second opening includes a part located inside of a central axis of the accommodation hole in a radial direction about a rotation axis of the vane rotor.

7. The internal combustion engine valve timing control device as claimed in claim 1 , wherein:

the first rotating member is the vane rotor;

the lock member includes a flange at an outer periphery of the rear end portion, wherein the flange is larger in diameter than the tip portion;

the accommodation hole includes a larger-diameter hole section for slidably supporting the flange, and a smaller-diameter hole section for slidably supporting a first part of the lock member closer to the tip portion than the flange;

the vane rotor includes an unlock passage;

the unlock passage is structured to provide communication between the working chamber and a first part of the larger-diameter hole section closer to the tip portion than the flange, when in the first state that the tip portion of the lock member is inserted in the lock hole; and

the first opening of the communication passage facing the back pressure chamber includes a part located outside of an opening of the unlock passage in a radial direction about a rotation axis of the vane rotor, wherein the opening of the unlock passage faces the back pressure chamber.

8. The internal combustion engine valve timing control device as claimed in claim 1 , wherein the first cross-sectional area is circular.

9. The internal combustion engine valve timing control device as claimed in claim 8 , wherein:

the first rotating member is the vane rotor;

the lock member includes a flange at an outer periphery of the rear end portion, wherein the flange is larger in outside diameter than the tip portion;

the accommodation hole includes a larger-diameter hole section for sliding of the flange, and a smaller-diameter hole section for sliding of a first part of the lock member closer to the tip portion than the flange;

the vane rotor includes an unlock passage;

the unlock passage is structured to provide communication between the working chamber and a first part of the larger-diameter hole section closer to the tip portion than the flange, when in the first state that the tip portion of the lock member is inserted in the lock hole; and

the first cross-sectional area of the communication passage is implemented by a circular hole smaller than a minimum cross-sectional area of the unlock passage.

10. The internal combustion engine valve timing control device as claimed in claim 1 , wherein:

the first rotating member is the vane rotor;

the lock member includes a flange at an outer periphery of the rear end portion, wherein the flange is larger in outside diameter than the tip portion;

the accommodation hole includes a larger-diameter hole section for sliding of the flange, and a smaller-diameter hole section for sliding of a first part of the lock member closer to the tip portion than the flange;

the vane rotor includes an unlock passage;

the unlock passage is structured to provide communication between the working chamber and a first part of the larger-diameter hole section closer to the tip portion than the flange, when in the first state that the tip portion of the lock member is inserted in the lock hole;

the communication passage and the unlock passage are implemented by a first hole; and

the communication passage is structured to communicate with the back pressure chamber via a throttling portion that is formed between a rear end edge of the flange and an inner periphery of the first hole when in the first state that the tip portion of the lock member is inserted in the lock hole.

11. The internal combustion engine valve timing control device as claimed in claim 10 , wherein the communication passage is structured such that the throttling portion is smaller in open cross-sectional area than the unlock passage when in the first state that the tip portion of the lock member is inserted in the lock hole.

12. The internal combustion engine valve timing control device as claimed in claim 1 , wherein:

the first rotating member is the vane rotor; and

the communication passage is formed in an outer end surface of the vane rotor, and is implemented by a groove that includes a first end opening facing the working chamber and a second end opening facing the back pressure chamber.

13. The internal combustion engine valve timing control device as claimed in claim 1 , wherein:

the communication passage includes a first recess and a second recess;

the first recess is formed in a part of the first rotating member in sliding contact with the second rotating member, and includes a first end opened to the back pressure chamber; and

the second recess is formed in a part of the second rotating member in sliding contact with the first rotating member, and includes a first end opened to the working chamber, and a second end opened to a second end of the first recess.

14. The internal combustion engine valve timing control device as claimed in claim 13 , wherein:

the first rotating member is the vane rotor, and is made of sintered metal;

the second rotating member is the housing, and includes a housing body having a tubular shape, and a plate part made of a metal plate and closing an opening of the housing body;

the first recess is formed in the vane rotor; and

the second recess is formed in the plate part by press forming.

15. The internal combustion engine valve timing control device as claimed in claim 1 , wherein:

the vane rotor is structured to separate the working chamber into a retard hydraulic chamber and an advance hydraulic chamber; and

the communication passage is opened to the retard hydraulic chamber.

16. The internal combustion engine valve timing control device as claimed in claim 1 , wherein:

the vane rotor is structured to separate the working chamber into a retard hydraulic chamber and an advance hydraulic chamber; and

the communication passage is opened to the advance hydraulic chamber.

17. An internal combustion engine valve timing control device comprising:

a housing structured to receive a torque from a crankshaft, wherein a working chamber is defined in the housing;

a vane rotor fixed to a camshaft, and rotatably mounted in the housing, and including a vane separating the working chamber into a plurality of separated working chambers;

an accommodation hole formed in the vane and extending in an axial direction of the vane rotor;

a lock member slidably mounted in the accommodation hole, and structured to be made by a hydraulic pressure to slide in one direction, and including a pressure-receiving part structured to receive the hydraulic pressure from one of the separated working chambers;

a lock hole formed in the housing, and structured to receive insertion of a tip portion of the lock member when the vane rotor is in a predetermined rotational position with respect to the housing, wherein the tip portion faces in a first slide direction of the lock member;

a back pressure chamber formed in a second slide direction from a rear end portion of the lock member in the accommodation hole, wherein the rear end portion faces in the second slide direction of the lock member;

a biasing member mounted in the back pressure chamber, and structured to bias the lock member in one direction;

an exhaust passage formed between the housing and the vane rotor, and structured to provide communication between the back pressure chamber and an outside of the housing; and

a communication passage formed in the vane rotor to communicate with the working chamber, and including an opening, wherein:

the opening is structured to be opened to the back pressure chamber when in a first state that the tip portion of the lock member is inserted in the lock hole, and be closed by the lock member when in a second state that the tip portion of the lock member is out of the lock hole;

a first cross-sectional area is smaller than a second cross-sectional area;

the first cross-sectional area is a smaller one of a minimum cross-sectional area of the communication passage and an open cross-sectional area of the opening; and

the second cross-sectional area is a minimum cross-sectional area of the exhaust passage.

18. The internal combustion engine valve timing control device as claimed in claim 17 , wherein the first cross-sectional area and the second cross-sectional area are set to have a ratio of the first cross-sectional area to the second cross-sectional area that is smaller than or equal to 0.18.

19. The internal combustion engine valve timing control device as claimed in claim 17 , wherein the first cross-sectional area is noncircular.