Shaft seal structure of vacuum pumps
AssigneeKabushiki Kaisha Toyota Jidoshokki
InventorsShinya Yamamoto, Masahiro Kawaguchi, Ryosuke Koshizaka
Life of this patent
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Abstract
A Roots pump rotates a plurality of rotors by a pair of rotary shafts to draw gas. Each rotary shaft extends through a rear housing member of the Roots pump. An annular shaft seal is fitted around each rotary shaft and is received in a recess formed in the rear housing member. A helical groove is formed in a circumferential side of each rotary shaft. Each helical groove urges oil between the circumferential side of the associated shaft seal and the circumferential wall of the recess to move from a side corresponding to pump chambers toward a gear accommodating chamber when the associated rotary shaft rotates. This preferably prevents oil from leaking to the pump chambers.
Claims17
A vacuum pump that draws gas by operating a gas conveying body in a pump chamber through rotation of a rotary shaft, the vacuum pump comprising:
- an oil housing member, wherein the oil housing member forms an oil zone adjacent to the pump chamber, and the rotary shaft has a projecting section that projects from the pump chamber to the oil zone through a through hole formed in the oil housing member;
- an annular shaft seal, which is located around the projecting section to rotate integrally with the rotary shaft, wherein the shaft seal has a first seal forming surface that opposes the oil housing member;
- a second seal forming surface, which is formed on the oil housing member, wherein the second seal forming surface opposes the first seal forming surface;
- a pumping means, which is formed at the first seal forming surface, wherein the pumping means urges oil between the first and second seal forming surfaces to move from a side corresponding to the pump chamber toward the oil zone when the rotary shaft rotates;
- and
- a pressure introducing line that introduces the pressure in a maximum pressure zone located in the pump chamber to the pumping means through the through hole.
A vacuum pump draws gas by operating a gas conveying body in a pump chamber through rotation of a rotary shaft, the vacuum pump comprising:
- a housing, wherein the housing has the pump chamber and an oil zone, the housing includes a partition that separates the pump chamber from the oil zone, and the rotary shaft extends from the pump chamber to the oil zone through a through hole formed in the partition;
- an annular shaft seal, which is fitted around the rotary shaft to rotate integrally with the rotary shaft, wherein the shaft seal has a first seal forming surface that opposes the partition;
- a second seal forming surface, which is formed on the partition, wherein the second seal forming surface opposes the first seal forming surface;
- a pumping mechanism, which is formed at the first seal forming surface, wherein the pumping mechanism urges oil between the first and second seal forming surfaces to move from a side corresponding to the pump chamber toward the oil zone when the rotary shaft rotates;
- and
- a pressure introducing line that introduces the pressure in a maximum pressure zone located in the pump chamber to the pumping mechanism through the through hole.
A Roots pump, comprising:
- a housing, wherein the housing has a pump chamber and an oil zone, and the housing includes a partition that separates the pump chamber from the oil zone;
- a pair of parallel rotary shafts, wherein each rotary shaft extends from the pump chamber to the oil zone through one of a pair of through holes formed in the partition;
- a pair of rotors, each of which is located in the pump chamber and is formed around one of the rotary shafts, wherein the rotor of one rotary shaft engages with the rotor of the other;
- a gear mechanism, which is located in the oil zone, wherein the gear mechanism connects the rotary shafts to each other such that the rotary shafts rotate integrally;
- a pair of annular shaft seals, each of which is located in the oil zone and is fitted around one of the rotary shafts to rotate integrally with the rotary shaft, wherein each shaft seal has a first seal forming surface that opposes the partition;
- a pair of second seal forming surfaces, which are formed on the partition, wherein each second seal forming surface opposes one of the first seal forming surfaces;
- a pair of pumping means, each at which is formed at one of the first seal forming surfaces, wherein each pumping means urges oil between the associated first and second seal forming surfaces to move from a side corresponding to the pump chamber toward the oil zone when the associated rotary shaft rotates;
- and
- a pair of pressure introducing lines, each of which introduces the pressure in a maximum pressure zone located in the pump chamber to one of the pumping means through one of the through holes.
Dependencies are inferred from the claim text.