Abstract: A hydraulic tensioner includes a cylinder having a hollow space filled with hydraulic oil. A plunger is slidably mounted in the cylinder. A pushrod is mounted in the hollow space so as to be axially movable together with the plunger with one end thereof protruding from the cylinder. A spring is mounted in the cylinder to bias the plunger and pushrod outwardly of the cylinder. The plunger is formed with a passage through which a pressure chamber and reservoir chamber communicate with each other. The passage is formed with a valve seat. A check ball is arranged so as to be moved into and out of contact with the valve seat. The check ball is adapted to contact the valve seat when pressure in the pressure chamber exceeds pressure in the reservoir chamber, thereby closing the passage. The valve seat is formed of a steel for carburizing and has a surface carbon concentration of 0.55–0.75% to reduce deposition of carbides and to have a surface hardness at least equal to that of the check ball.

Abstract: A chain tensioner for use in a chain system for driving a vehicle engine, particularly a two-wheeled vehicle engine, includes a housing and a plunger slidably mounted in the cylinder chamber formed in the housing. The plunger is biased outwardly by a return spring mounted in a pressure chamber defined in the cylinder chamber by the plunger. A check valve is provided at the closed end of the cylinder chamber to prevent backflow of hydraulic oil in the pressure chamber. A relief valve is provided in the plunger. The relief valve has a relief pressure above which the relief valve opens, thereby discharging hydraulic oil in the pressure chamber. An oil leakage clearance is defined between the inner wall of the cylinder chamber and the radially outer surface of the plunger through which hydraulic oil in the pressure chamber can leak out.

Abstract: An apparatus for sending and receiving information to and from a plurality of other apparatuses with wireless communications is disclosed.

Abstract: A chain tensioner includes a housing having a cylinder chamber. A plunger is slidably mounted in the cylinder chamber. A spring is mounted in the cylinder chamber to bias the plunger outwardly of the cylinder chamber. The plunger has a radially extending locking pin at its lower portion near its front end. The housing is formed with a pin hole extending substantially perpendicular to an axis of the cylinder chamber near the front end of the housing and under the cylinder chamber. The chain tensioner further includes a support pin inserted in the pin hole, and a locking lever supported on the support pin so as to be pivotable about the support pin. The locking lever can engage the locking pin when the plunger is sufficiently pushed into the cylinder chamber, thereby keeping the plunger pushed in the cylinder chamber.

Abstract: It is desired to improve the wear resistance of the valve seat of the check valve in a hydraulic tensioner. The hydraulic tensioner includes a cylinder having a hollow space filled with hydraulic oil. A plunger is slidably mounted in the cylinder. A pushrod is mounted in the hollow space so as to be axially movable together with the plunger with one end thereof protruding from the cylinder. A spring is mounted in the cylinder to bias the plunger and pushrod outwardly of the cylinder. The plunger is formed with a passage through which the pressure chamber and the reservoir chamber communicate with each other. The passage is formed with a valve seat. A check ball is arranged so as to be moved into and out of contact with the valve seat. The check ball is adapted to contact the valve seat when the pressure in the pressure chamber exceeds the pressure in the reservoir chamber, thereby closing the passage. The valve seat is formed of a steel for carburizing and has a surface carbon concentration of 0.55-0.

Abstract: A communication navigation system, wherein a navigation apparatus requests a recommended route guidance data to a information center and guides a user of the navigation apparatus to a destination by using the recommended route guidance data received from the information center. In this present invention, the navigation apparatus transmits version data of road data held in the navigation apparatus at the request to the information center. The information center prepares a guidance data of recommended route using latest road data held in the information center, and transmits the data to the navigation apparatus. When the information center transmits the guidance data, the information center selects the type of data of the road links along the recommended route, in the guidance data, by comparing the version data received from the navigation apparatus and the version data of each road link along the recommended route.

Abstract: A communication route guidance system provides exchange of data between an information center and each of a plurality of mobile units such as vehicles. The information center has the latest road data and searches it to prepare recommended route guidance data in response to a request from the mobile unit. The reccommended route guidance data is divided into a plurality of data segments, each usable as an independent guidance instruction in the mobile unit. The mobile unit has stored therein road data similar to the road data in the information center and determines if data communication with the information center is available. In a case where the mobile unit can not communicate with the information center, the mobile unit prepares route guidance based on the road data stored in the mobile unit. It thereby becomes possible to guide the user even in the case that the mobile unit can not communicate with the information center.

Abstract: A navigation system includes a navigation center and at least one moving body. The navigation center of the navigation system comprises memory means for storing navigation information; updating means for constantly updating the navigation information stored in the memory means; route searching means for setting a route from a current position of the moving body to a destination on the basis of the newest navigation information updated by the updating means; dividing means for dividing the searched route into at least two portions; extracting means for extracting navigation data concerning at least a head portion of the divided route from the memory means; transmitting means for transmitting to the moving body the extracted navigation data; and control means.

Abstract: In a communications navigation system, data is transmitted and received between a navigation base apparatus provided at a navigation base and each of a plurality of navigation apparatuses provided in moving bodies such as vehicles using communication. A determining section of the navigation base apparatus determines untraveled route portion by comparing user's information stored in a user information storage with information of a recommended route provided by a route search section. The navigation base apparatus extracts necessary route/guidance information for untraveled route portion determined by the determining section from route/guidance data stored in a database, and then transmits the extracted route/guidance data to the navigation apparatus identified by the identification information. The route/guidance information may be transmitted to the navigation apparatus in the form of segmented data.

Abstract: A navigation system includes a navigation center and a plurality of navigation apparatuses each of which has a data storage that stores various information. In this navigation system, data (coordinate data of each of traveling intersections) concerning a recommended route is transmitted from the navigation center to the navigation apparatus, and then route guidance is carried out in the navigation apparatus using the data received from the navigation center. In the case where the navigation apparatus has intersection data for an intersection specified by the data received from the navigation center, the navigation apparatus extracts the intersection data for the intersection from the data storage. Further, in the case where the navigation center does not have intersection data for an intersection specified by the data received from the navigation center, the navigation apparatus establishes the intersection as a newly-built intersection on the recommended route.

Abstract: Disclosed is a communicatory navigation system including an information center (150), at least one navigation unit (100) each mounted on a vehicle and communication means for allowing bi-directional data communication between the information center and the navigation unit. Data transmission from the navigation unit to the information center is made during a period of communication that begins when the navigation unit become communicable with the information center and ends when the bi-directional data communication therebetween is disconnected. The navigation unit is provided with a drive route history memory area (131) and an instrument operation history memory area (132), and data in these memory areas are transmitted to the information center, together with the vehicle current position data and the destination position data.

Abstract: A commucations navigation system in which data is transmitted and received between a navigation base apparatus provided at a navigation base and a vehicle navigation apparatus provided in a vehicle using communication. The vehicle navigation apparatus is adapted to transmit at least data concerning the current position of the vehicle and the destination thereof to the navigation base apparatus, and the navigation base apparatus stores navigation data in its data base and is adapted to determine a recommended route based on the transmitted data of the current position of the vehicle and the destination thereof and then extract data of the recommended route from the navigation data stored in the data base and transmit the extracted data to the navigation apparatus.

Abstract: Disclosed is a communicatory navigation system including an information center (150), at least one navigation unit (100) each mounted on a vehicle and communication means for allowing bi-directional data communication between the information center and the navigation unit. Data transmission from the navigation unit to the information center is made during a period of communication that begins when the navigation unit become communicatable with the information center and ends when the bi-directional data communication therebetween is disconnected. The navigation unit is provided with a drive route history memory area (131) and an instrument operation history memory area (132), and data in these memory areas are transmitted to the information center, together with the vehicle current position data and the destination position data.

Abstract: A hydraulic autotensioner has a cylinder having a closed bottom end, a sleeve mounted in the cylinder and a plunger slidably mounted in the sleeve. The interior of the cylinder is divided into a reservoir chamber and a pressure chamber by the plunger which is formed with a passage through which the reservoir chamber and the pressure chamber communicate with each other. A check valve is provided in the passage to close the passage if the pressure of hydraulic oil in the pressure chamber increases above the pressure of hydraulic oil in the reservoir chamber. A return spring is mounted in the cylinder to bias a rod which is axially movable together with the plunger in such a direction as to protrude from an upper opening of the cylinder. The return spring is mounted in a space formed between the outer peripheral surface of the sleeve and the inner peripheral surface of the cylinder.

Abstract: A hydraulic autotensioner has a cylinder having a closed bottom end, a sleeve mounted in the cylinder and a plunger slidably mounted in the sleeve. The interior of the cylinder is divided into a reservoir chamber and a pressure chamber by the plunger which is formed with a passage through which the reservoir chamber and the pressure chamber communicate with each other. A check valve is provided in the passage to close the passage if the pressure of hydraulic oil in the pressure chamber increases above the pressure of hydraulic oil in the reservoir chamber. A return spring is mounted in the cylinder to bias a rod which is axially movable together with the plunger in such a direction as to protrude from an upper opening of the cylinder. The return spring is mounted in a space formed between the outer peripheral surface of the sleeve and the inner peripheral surface of the cylinder.

Abstract: An autotensioner having a fixed shaft, a pulley support pivotally supported on the fixed shaft, a pulley rotatably supported on the pulley support and a spring for biasing the pulley support in such a direction as to apply tension to a belt. The pulley support has a cylindrical portion arranged coaxially with the fixed shaft. The fixed shaft is formed with cam surfaces at such a position that wedge-shaped spaces are defined between the cam surfaces and the cylindrical portion. The wedge-shaped spaces narrow in a direction in which the pulley support pivots to slacken the belt. Friction members are each mounted in the respective wedge-shaped spaces. They have a shape substantially complementary to the shape of the wedge-shaped spaces. A spring member is also mounted in each wedge-shaped space to bias the friction members into the narrow area of each wedge-shaped space.