US 9,810,297 B2
Hydraulic auto-tensioner for engine accessory
Satoshi Kitano, Shizuoka (JP); Tsuyoshi Fukahori, Shizuoka (JP); Aisaku Satomura, Shizuoka (JP); and Masayoshi Yamada, Shizuoka (JP)
Assigned to NTN CORPORATION, Osaka (JP)
Appl. No. 14/435,192
Filed by NTN CORPORATION, Osaka (JP)
PCT Filed Oct. 11, 2013, PCT No. PCT/JP2013/077777
§ 371(c)(1), (2) Date Apr. 13, 2015,
PCT Pub. No. WO2014/061593, PCT Pub. Date Apr. 24, 2014.
Claims priority of application No. 2012-228899 (JP), filed on Oct. 16, 2012; application No. 2012-255028 (JP), filed on Nov. 21, 2012; and application No. 2012-265196 (JP), filed on Dec. 4, 2012.
Prior Publication US 2015/0252878 A1, Sep. 10, 2015
Int. Cl. F16H 7/08 (2006.01); F16H 7/12 (2006.01)
CPC F16H 7/0836 (2013.01) [F16H 7/0848 (2013.01); F16H 7/1236 (2013.01); F16H 2007/0806 (2013.01); F16H 2007/0814 (2013.01); F16H 2007/0859 (2013.01); F16H 2007/0893 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A hydraulic auto-tensioner for use with an engine accessory, comprising:
a cylinder containing hydraulic oil and including a bottom portion having an upper surface formed with a sleeve fit-in hole;
a sleeve having a lower end portion press-fitted in the sleeve fit-in hole;
a rod having a lower end portion slidably inserted in the sleeve and defining a pressure chamber in the sleeve;
a return spring incorporated between a spring washer provided at an upper part of the rod and the upper surface of the bottom portion of the cylinder and biasing the cylinder and the rod in a direction in which the rod protrudes from the cylinder;
a tubular spring cover provided on the spring washer and covering an upper part of the return spring;
a seal member incorporated in an upper side opening of the cylinder and having an inner periphery kept in elastic contact with an outer periphery of the spring cover, thereby defining a reservoir chamber between the cylinder and the sleeve, an oil passage being defined between fitting surfaces of the sleeve and the sleeve fit-in hole such that the reservoir chamber communicates with the pressure chamber through the oil passage; and
a check valve mounted in the lower end portion of the sleeve and configured to be closed, thereby disconnecting the pressure chamber from the oil passage, when a pressure in the pressure chamber becomes higher than a pressure in the reservoir chamber,
wherein the sleeve has a lower end face in abutment with a bottom surface of the sleeve fit-in hole, the bottom surface of the sleeve fit-in hole having:
an annular inner peripheral surface portion;
an annular outer peripheral surface portion surrounding the annular inner peripheral surface portion and located at a higher level than the annular inner peripheral surface portion; and
an oil sump surrounded by the annular inner peripheral surface portion.