Switchable rocker arm

1. A rocker arm for transmitting rotational motion from a camshaft to opening and closing motion of a combustion valve in an internal combustion engine, said rocker arm comprising:

an outer arm having a first wall surface, a second wall surface opposed to, and spaced apart from, said first wall surface, and a third wall surface which joins said first wall surface to said second wall surface, said first wall surface, said second wall surface, and said third wall surface together forming a lock member channel which is open in a direction away from said third wall surface;

an inner arm which selectively pivots relative to said outer arm about a pivot axis;

a lost motion spring which biases said inner arm to pivot relative to said outer arm in a first direction about said pivot axis;

a lock member located within said lock member channel, wherein said lock member moves along a lock member axis between 1) a coupled position in which said lock member prevents said inner arm from pivoting about said pivot axis relative to said outer arm past a predetermined position of said inner arm relative to said outer arm in a second direction which is opposite of said first direction and 2) a decoupled position in which said lock member permits said inner arm to pivot relative to said outer arm past said predetermined position in said second direction about said pivot axis; and

a lock member retainer which is spaced apart from, and opposed to, said third wall surface such that said lock member is captured between said lock member retainer and said third wall surface, thereby limiting movement of said lock member away from said third wall surface in the direction away from said third wall surface which is perpendicular to said lock member axis

wherein said first wall surface, said second wall surface, and said third wall surface extend along a common portion of said lock member axis.

2. The rocker arm as in claim 1 , wherein:

said first wall surface is provided on a first wall which includes a first wall aperture;

said second wall surface is provided on a second wall which includes a second wall aperture; and

said lock member retainer is located within said first wall aperture and said second wall aperture.

3. The rocker arm as in claim 2 , wherein said first wall aperture and said second wall aperture each extend along a lock member retainer axis which is parallel to said pivot axis.

4. The rocker arm as in claim 2 , wherein said first wall aperture and said second wall aperture are each cylindrical.

5. The rocker arm as in claim 4 , wherein said lock member retainer is cylindrical.

6. The rocker arm as in claim 1 , wherein:

said first wall surface is planar; and

said second wall surface is planar and is parallel to said first wall surface.

7. The rocker arm as in claim 6 , wherein said lock member includes:

a first lock member surface which faces toward said first wall surface;

a second lock member surface which faces toward said second wall surface and which is parallel to said first lock member surface; and

a third lock member surface which joins said first lock member surface to said second lock member surface and which faces toward said third wall surface.

8. The rocker arm as in claim 7 , wherein;

said lock member includes a fourth lock member surface which faces toward said lock member retainer and which is laterally offset from said third lock member surface by a first distance;

said lock member includes a fifth lock member surface which is laterally offset from said third lock member surface by a second distance which is greater than said first distance, thereby forming a lock member shoulder which joins said fourth lock member surface and said fifth lock member surface; and

said lock member shoulder limits travel of said lock member by engaging said lock member retainer only when said lock member is in said coupled position.

9. The rocker arm as in claim 8 , wherein:

said third lock member surface is planar; and

said fourth lock member surface is planar and parallel to said third lock member surface.

10. The rocker arm as in claim 8 , wherein said lock member shoulder is perpendicular to said third lock member surface.

11. The rocker arm as in claim 7 , wherein:

said first lock member surface is planar; and

said second lock member surface is planar.

12. The rocker arm as in claim 1 , wherein said outer arm includes an outer arm first wall and an outer arm second wall such that said outer arm first wall and said outer arm second wall are spaced apart from each other, said outer arm first wall and said outer arm second wall having respective surfaces which define a central opening within which said inner arm is located.

13. The rocker arm as in claim 12 , wherein said respective surfaces of said outer arm first wall and said outer arm second wall are distinct from said first wall surface and said second wall surface.

14. A rocker arm for transmitting rotational motion from a camshaft to opening and closing motion of a combustion valve in an internal combustion engine, said rocker arm comprising:

an outer arm having a first wall surface, a second wall surface opposed to, and spaced apart from, said first wall surface, and a third wall surface which joins said first wall surface to said second wall surface, said first wall surface, said second wall surface, and said third wall surface together forming a lock member channel which is open in a direction away from said third wall surface;

an inner arm which selectively pivots relative to said outer arm about a pivot axis;

a lost motion spring which biases said inner arm to pivot relative to said outer arm in a first direction about said pivot axis;

a lock member located within said lock member channel, wherein said lock member moves along a lock member axis between 1) a coupled position in which said lock member prevents said inner arm from pivoting about said pivot axis relative to said outer arm past a predetermined position of said inner arm relative to said outer arm in a second direction which is opposite of said first direction and 2) a decoupled position in which said lock member permits said inner arm to pivot relative to said outer arm past said predetermined position in said second direction about said pivot axis; and

a lock member retainer which is spaced apart from, and opposed to, said third wall surface such that said lock member is captured between said lock member retainer and said third wall surface, thereby limiting movement of said lock member away from said third wall surface in the direction away from said third wall surface which is perpendicular to said lock member axis;

wherein said first wall surface is planar;

wherein said second wall surface is planar and is parallel to said first wall surface; and

wherein said lock member includes:

a first lock member surface which faces toward said first wall surface;

a second lock member surface which faces toward said second wall surface and which is parallel to said first lock member surface; and

a third lock member surface which joins said first lock member surface to said second lock member surface and which faces toward said third wall surface wherein said third lock member surface engages said third wall surface such that said third lock member surface slides across said third wall surface when said lock member moves between said coupled position and said decoupled position.

15. A rocker arm for transmitting rotational motion from a camshaft to opening and closing motion of a combustion valve in an internal combustion engine, said rocker arm comprising:

an outer arm having a first wall surface, a second wall surface opposed to, and spaced apart from, said first wall surface, and a third wall surface which joins said first wall surface to said second wall surface, said first wall surface, said second wall surface, and said third wall surface together forming a lock member channel which is open in a direction away from said third wall surface;

an inner arm which selectively pivots relative to said outer arm about a pivot axis;

a lost motion spring which biases said inner arm to pivot relative to said outer arm in a first direction about said pivot axis;

a lock member located within said lock member channel, wherein said lock member moves along a lock member axis between 1) a coupled position in which said lock member prevents said inner arm from pivoting about said pivot axis relative to said outer arm past a predetermined position of said inner arm relative to said outer arm in a second direction which is opposite of said first direction and 2) a decoupled position in which said lock member permits said inner arm to pivot relative to said outer arm past said predetermined position in said second direction about said pivot axis; and

a lock member retainer which is spaced apart from, and opposed to, said third wall surface such that said lock member is captured between said lock member retainer and said third wall surface, thereby limiting movement of said lock member away from said third wall surface in the direction away from said third wall surface which is perpendicular to said lock member axis;

wherein said first wall surface is planar;

wherein said second wall surface is planar and is parallel to said first wall surface;

wherein said lock member includes:

a first lock member surface which faces toward said first wall surface;

a second lock member surface which faces toward said second wall surface and which is parallel to said first lock member surface; and

a third lock member surface which joins said first lock member surface to said second lock member surface and which faces toward said third wall surface;

wherein said lock member includes a lock member aperture extending through said lock member from said first lock member surface to said second lock member surface; and

wherein said rocker arm further comprises a lock member travel stop fixed to said outer arm which passes through said lock member aperture and which limits travel of said lock member in said decoupled position.

16. The rocker arm as in claim 15 , wherein:

said outer arm includes a first outer arm aperture extending into said outer arm from said first wall surface;

said outer arm includes a second outer arm aperture extending into said outer arm from said second wall surface; and

said lock member travel stop is located within said first outer arm aperture and said second outer arm aperture.

17. The rocker arm as in claim 15 , wherein said lock member aperture is open toward said first wall surface and toward said second wall surface.

18. The rocker arm as in claim 15 , wherein said rocker arm further comprises a return spring which is grounded to said lock member travel stop and urges said lock member toward said decoupled position.

19. The rocker arm as in claim 18 , wherein said return spring is located within said lock member aperture.