1. A power steering system comprising:
a worm wheel linked to a steering shaft;
a wormshaft housed in a housing and adapted to mesh with the worm wheel;
a bearing adapted to rotatably support one end of the wormshaft;
a bearing holder having a substantially cylindrical holding portion formed to enclose and fit onto the bearing for holding the bearing; and
a preloading means located in the bearing holder for preloading the bearing in a direction that the wormshaft and the worm wheel are brought into meshed-engagement with each other,
wherein a shaft housing portion is defined in the housing for housing the wormshaft inside of the housing;
a holder housing portion is provided at one axial end of the shaft housing portion for housing the bearing holder;
the holder housing portion has a restriction wall for restricting a movement of the bearing holder at least in an opposite direction, which is opposite to the direction that the wormshaft and the worm wheel are brought into meshed-engagement with each other, and in a direction perpendicular to the opposite direction; and
an inner peripheral surface of the holder housing portion, defined by the restriction wall, is formed into a substantially circular shape in lateral cross-section, and a central axis of the inner peripheral surface of the holder housing portion and a central axis of an inner peripheral surface of the shaft housing portion are configured to substantially coincide with each other.
2. The power steering system as claimed in claim 1, wherein:
the preloading means comprises a preload portion formed integral with the holding portion of the bearing holder to permit elastic deformation of the preload portion, for forcing the bearing in the direction that the wormshaft and the worm wheel are brought into meshed-engagement with each other, by a force of resiliency of the preload portion.
3. The power steering system as claimed in claim 2, wherein:
the bearing holder is formed of a synthetic resin.
4. The power steering system as claimed in claim 2, further comprising:
a preload member adapted to be kept in resilient-contact with an outer surface of the preload portion, for assisting a preload of the preload portion.
5. The power steering system as claimed in claim 4, wherein:
the bearing holder is formed into a substantially cylindrical shape by both the holding portion and the preload portion, and the preload member comprises an O ring fitted to an outer circumference of the bearing holder.
6. The power steering system as claimed in claim 5, wherein:
the preload member is configured to apply a preload to the preload portion by a radial shrinking action of the O ring.
7. The power steering system as claimed in claim 5, wherein:
the O ring is fitted and retained in grooves cut and formed in respective outer circumferences of the holding portion and the preload portion.
8. The power steering system as claimed in claim 2, wherein:
the bearing holder has a bottom wall and a peripheral wall formed to extend upward from a circumference of the bottom wall for retaining an outer peripheral surface of the bearing, and the preload portion is supported by the bottom wall of the holding portion via a pair of slits, which slits are radially cut out and formed to range from the peripheral wall of the bearing holder to a predetermined position of the bottom wall.
9. The power steering system as claimed in claim 8, wherein:
the pair of slits are formed such that a circumferential width of the preload portion gradually enlarges radially outward from a basal-end portion of the preload portion formed integral with the bottom wall of the holding portion.
10. The power steering system as claimed in claim 8, wherein:
a stiffness of a basal-end portion of a bottom of the preload portion is set to be less than a stiffness of an outermost-end portion of the bottom of the preload portion.
11. The power steering system as claimed in claim 2, wherein:
the preload portion has a plurality of spring-stiffness characteristic values for a load-deflection characteristic with regard to an input load.
12. A speed reduction mechanism comprising:
a first gear housed in a housing and rotated by an actuator;
a second gear adapted to mesh with the first gear;
a bearing adapted to rotatably support at least one end of the first gear;
a bearing holder having a substantially cylindrical holding portion formed to enclose and fit onto the bearing for holding the bearing; and
a preloading means located in the bearing holder for preloading the bearing in a direction that the first gear and the second gear are brought into meshed-engagement with each other,
wherein a first gear housing portion is defined in the housing for housing the first gear inside of the housing;
a holder housing portion is provided at one axial end of the first gear housing portion for housing the bearing holder; the holder housing portion has a restriction wall arranged coaxially with the first gear housing portion for restricting a movement of the bearing holder at least in an opposite direction, which is opposite to the direction that the first gear and the second gear are brought into meshed-engagement with each other, and in a direction perpendicular to the opposite direction, and
an inner peripheral surface of the holder housing portion, defined by the restriction wall, is formed into a substantially circular shape in lateral cross-section, and a central axis of the inner peripheral surface of the holder housing portion and a central axis of an inner peripheral surface of the first gear housing portion are configured to substantially coincide with each other.
13. The speed reduction mechanism as claimed in claim 12, wherein:
the bearing holder has a restriction portion provided to restrict an axial movement of the first gear toward the one end of the first gear through the bearing.
14. The speed reduction mechanism as claimed in claim 12, wherein:
the first gear comprises a wormshaft, whereas the second gear comprises a worm wheel; and
the worm wheel is formed of a synthetic resin.
15. The speed reduction mechanism as claimed in claim 12, further comprising:
a preload member installed on the bearing holder, for assisting a preload of the preload means.
16. The speed reduction mechanism as claimed in claim 15, wherein:
the preload member comprises an O ring fitted to an outer circumference of the bearing holder.
17. A bearing holder for holding a bearing installed on one end of a wormshaft adapted to mesh with a worm wheel, comprising:
a substantially cylindrical holding portion formed to enclose and fit onto the bearing and housed and retained in a holder housing portion, which is arranged coaxially with a shaft housing portion defined in the housing for housing the wormshaft;
a guide portion provided in an inner circumference of the holding portion for permitting a movement of the bearing in a direction that the wormshaft and the worm wheel are brought into meshed-engagement with each other, and for restricting a movement of the bearing in a direction perpendicular to the direction of meshed-engagement; and
a preloading means provided for preloading the bearing in the direction that the wormshaft and the worm wheel are brought into meshed-engagement with each other,
wherein an inner peripheral surface of the holder housing portion is formed into a substantially circular in lateral cross-section and a central axis of the inner peripheral surface of the holder housing portion and a central axis of an inner peripheral surface of the shaft housing portion are configured to substantially coincide with each other.
18. The bearing holder as claimed in claim 17, wherein:
the preloading means comprises a preload portion formed integral with the holding portion to permit elastic deformation of the preload portion, for forcing the bearing in the direction that the wormshaft and the worm wheel are brought into meshed-engagement with each other, by a force of resiliency of the preload portion.
19. The bearing holder as claimed in claim 18, wherein:
the bearing holder has a bottom wall and a peripheral wall formed to extend upward from a circumference of the bottom wall for retaining an outer peripheral surface of the bearing; and
the preload portion is supported by the bottom wall of the holding portion via a pair of slits, which slits are radially cut out and formed to range from the peripheral wall of the bearing holder to a predetermined position of the bottom wall.
20. The bearing holder as claimed in claim 19, wherein:
the pair of slits are formed such that a circumferential width of the preload portion gradually enlarges radially outward from a basal-end portion of the preload portion formed integral with the bottom wall of the holding portion.
21. The power steering system as claimed in claim 1, wherein:
the inner peripheral surface of the holder housing portion is configured by a generatorix parallel to a generatorix that generates the inner peripheral surface of the shaft housing portion.
22. The power steering system as claimed in claim 1, wherein:
the bearing is movably housed in the bearing holder; and
the preload means is located on an outer circumference of the bearing holder for preloading the bearing through the bearing holder.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A computer-implemented method of providing two-level joint login authentication, comprising:
at a device having one or more processors and memory:
receiving a first-level login request from a first client device, the first-level login request including first user login information associated with a user;
in response to the first-level login request:
generating respective security enhancement information for the first-level login request;
providing the security enhancement information to the first client device; and
establishing a time window for authenticating the user through a second-level login process initiated by a respective client device different from the first client device, wherein the second-level login process requires the user to provide second user login information in accordance with the security enhancement information that has been generated and provided to the first client device in response to the first-level login request received from the first client device, and wherein the device establishes a single login session based on the first-level login request received from the first client device and the second user login information received from the respective client device different from the first client device;
during the time window for authenticating the user through the second-level login process, receiving a second-level login request from a second client device, the second-level login request including complete login information provided by the user at the second client device, and respective identifying information for the security enhancement information;
retrieving the security enhancement information based on the respective identifying information; and
verifying the complete login information included in the second login request based on pre-stored original login information associated with the user and the retrieved security enhancement information.
2. The method of claim 1, wherein generating the security enhancement information for the first-level login request further comprises:
for the received first-level login request, generating a respective mapping table for converting a plurality of original characters to a plurality of post-mapping characters.
3. The method of claim 2, wherein generating the security enhancement information for the first-level login request further comprises:
for the received first-level login request, generating a respective mapping serial number for the respective mapping table.
4. The method of claim 1, wherein the first-level login request includes incomplete login information associated with the user.
5. The method of claim 1, wherein the second user login information comprises complete user login information modified in accordance with the security enhancement information.
6. A non-transitory computer-readable medium having instructions stored thereon, the instructions, when executed by one or more processors, cause the processors to perform operations comprising:
receiving a first-level login request from a first client device, the first-level login request including first user login information associated with a user;
in response to the first-level login request:
generating respective security enhancement information for the first-level login request;
providing the security enhancement information to the first client device; and
establishing a time window for authenticating the user through a second-level login process initiated by a respective client device different from the first client device, wherein the second-level login process requires the user to provide second user login information in accordance with the security enhancement information that has been generated and provided to the first client device in response to the first-level login request received from the first client device, and wherein the device establishes a single login session based on the first-level login request received from the first client device and the second user login information received from the respective client device different from the first client device;
during the time window for authentication the user through the second-level login process, receiving a second-level login request from a second client device, the second-level login request including complete login information provided by the use at the second client device, and respective identifying information for the security enhancement information;
retrieving the security enhancement information based on the respective identifying information; and
verifying the complete login information included in the second login request based on pre-stored original login information associated with the user and the retrieved security enhancement information.
7. The computer-readable medium of claim 6, wherein generating the security enhancement information for the first-level login request further comprises:
for the received first-level login request, generating a respective mapping table for converting a plurality of original characters to a plurality of post-mapping characters.
8. The computer-readable medium of claim 7, wherein generating the security enhancement information for the first-level login request further comprises:
for the received first-level login request, generating a respective mapping serial number for the respective mapping table.
9. The computer-readable medium of claim 6, wherein the first-level login request includes incomplete login information associated with the user.
10. The computer-readable medium of claim 6, wherein the second user login information comprises complete user login information modified in accordance with the security enhancement information.
11. A system, comprising:
one or more processors; and
memory having instructions stored thereon, the instructions, when executed by the one or more processors, cause the processors to perform operations comprising:
receiving a first-level login request from a first client device, the first-level login request including first user login information associated with a user;
in response to the first-level login request:
generating respective security enhancement information for the first-level login request;
providing the security enhancement information to the first client device; and
establishing a time window for authenticating the user through a second-level login process initiated by a respective client device different from the first client device, wherein the second-level login process requires the user to provide second user login information in accordance with the security enhancement information that has been generated and provided to the first client device in response to the first-level login request received from the first client device and wherein the device establishes a single login session based on the first-level login request received from the first client device and the second user login information received from the respective client device different from the first client device;
during the time window for authentication the user through the second-level login process, receiving a second-level login request from a second client device, the second-level login request including complete login information provided by the use at the second client device, and respective identifying information for the security enhancement information;
retrieving the security enhancement information based on the respective identifying information; and
verifying the complete login information included in the second login request based on pre-stored original login information associated with the user and the retrieved security enhancement information.
12. The system of claim 11, wherein generating the security enhancement information for the first-level login request further comprises:
for the received first-level login request, generating a respective mapping table for converting a plurality of original characters to a plurality of post-mapping characters.
13. The system of claim 12, wherein generating the security enhancement information for the first-level login request further comprises:
for the received first-level login request, generating a respective mapping serial number for the respective mapping table.
14. The system of claim 11, wherein the first-level login request includes incomplete login information associated with the user.
15. The system of claim 11, wherein the second user login information comprises complete user login information modified in accordance with the security enhancement information.