Engine with chain tensioner

1. An engine comprising:

a case member;

a drive shaft journaled on the case member;

a drive rotation member secured to the drive shaft;

a driven shaft journaled on the case member;

a driven rotation member secured to the driven shaft;

an endless transmission belt connected to the drive rotation member and the driven rotation member;

a guide member disposed so as to make contact with the endless transmission belt, one end section of the guide member being swingably supported on the case member and the other end section of the guide member a free end; and

a chain tensioner for pressing the free end of the guide member to apply tension to the endless transmission belt,

wherein the chain tensioner includes:

(i) an accommodating concave section disposed in the case member, wherein an outer side of the accommodating concave section in a direction parallel to an axis of rotation of the drive shaft has an opening section;

(ii) an elastic member being accommodated in the accommodating concave section to press the guide member toward the endless transmission belt; and

(iii) a lid member covering the opening section of the accommodating concave section in the direction of the axis of rotation of the drive shaft.

2. The engine according to claim 1 , wherein the elastic member is a coil spring, and the guide member has a protruding section formed on a face on a side of the chain tensioner and engaged with an inside space of the coil spring.

3. The engine according to claim 2 , wherein the protruding section has a tapered shape.

4. The engine according to claim 1 , wherein a clearance between the elastic member and the case member in a movement direction of the endless transmission belt being wider than a clearance between the elastic member and the case member in a direction approximately orthogonal to the movement direction of the endless transmission belt.

5. The engine according to claim 1 , wherein the lid member is secured to the case member.

6. The engine according to claim 1 , further comprising an oil pipe having a joint section,

wherein the lid member holds the joint section of the oil pipe in the direction of the axis of rotation of the drive shaft.

7. The engine according to claim 1 , wherein the driven shaft is a pump driving shaft for driving an oil pump and/or a cooling water pump.

8. The engine according to claim 1 , wherein the accommodating concave section is formed by an indentation in a side wall of the case member, and

wherein a clearance of the elastic member is formed between the case member and the elastic member.

9. The engine according to claim 1 , wherein the lid member has a face which confines the elastic member and which faces in a direction parallel to the axis of rotation of the drive shaft.

10. The engine according to claim 1 , wherein the lid member is secured to the case member by a fastener which is spaced apart from the accommodating concave section.

11. The engine according to claim 10 , wherein the elastic member is a coil spring, and the opening section of the accommodating concave section is disposed outwardly of the coil spring in a radial direction of the coil spring, and

wherein the lid member faces in the radial direction of the coil spring.

12. The engine according to claim 1 , wherein the elastic member is a coil spring, and the opening section of the accommodating concave section is disposed outwardly of the coil spring in a radial direction of the coil spring, and

wherein the lid member faces in the radial direction of the coil spring.

13. The engine according to claim 1 , further comprising a pump,

wherein the driven shaft drives the pump.