In the production of hydraulic brake line assemblies used on motor vehicles such as automobiles, it is common to use a multi-layer high pressure flexible hose of the type disclosed in U.S. Pat. No. 5,445,191. As generally illustrated in this patent, the hose includes an inner rubber tube, an outer rubber tube and an intermediate rubber tube with the inner rubber tube and the intermediate rubber tube each surrounded by braided reinforcing fibers. Such a flexible hose is commonly used in combination with bendable high pressure steel pipe or tubes having an outside diameter of about {fraction (3/16)}xe2x80x3 and an inside diameter of about xe2x85x9xe2x80x3. Various types of special brass fittings are used to connect the flexible hose to the steel tubing and to connect the flexible hose to a caliper for a disk brake or to a hydraulic cylinder for a drum and shoe brake.
When a flexible high-pressure hose is connected to a brake caliper, it is common to use a fitting having a xe2x80x9cbanjoxe2x80x9d head portion, for example, of the type disclosed in U.S. Pat. No. 4,626,006. Such a fitting is usually machined or fabricated from solid brass and includes a crimping collar or sleeve surrounding an end portion of the brake hose and a smaller concentric tubular nipple or eyelet which projects into the end portion of the tube. The brass eyelet has axially spaced circumferential ridges which grip the hose when the collar or sleeve is crimped inwardly against the end portion of the hose. The eyelet is sometimes formed as an integral part of the brass fitting, as shown in the ""006 patent, or the eyelet may be a separate brass tube which is pressed into the collar or fitting and then brazed. The xe2x80x9cbanjoxe2x80x9d head portion disclosed in the ""006 patent comprises a block or eye-joint portion which has a cross bore for receiving a steel screw having internal fluid passages and threaded into the body of the caliper. The screw also extends through a pair of copper washers positioned on opposite sides of the fitting for forming high pressure seals between the fitting and the caliper. Frequently, the fitting has an internally threaded female fitting portion which is machined from brass along with the collar and eyelet.
A brass fitting with a collar and an integral or pressed-in nipple or eyelet and with a xe2x80x9cbanjoxe2x80x9d head portion, such as disclosed in the ""006 patent, is an expensive component for connecting the flexible brake hose to a brake caliper or cylinder, and adds significantly to the costs of the brake line assembly. When a bendable steel or brass tube is used to connect xe2x80x9cbanjoxe2x80x9d head portion to a flexible rubber hose, one end portion of the tube is brazed to the head portion, and the opposite end portion of the tube is brazed to a brass fitting which has a collar and an internal eyelet that is also brazed to the fitting or machined as an integral part of the collar. Thus the various fittings which are commonly used to connect the opposite end portions of a high pressure hose to a bendable steel tube and to a hydraulic cylinder within a brake caliper or for brake shoes usually require a brazing operation followed by a plating operation which add significantly to the cost of the brake line assembly and result in additional possible leak paths for the hydraulic fluid. In addition, many of the brass fittings commonly used are internally threaded or female fittings which are more difficult to produce in high volume with precision internal surfaces. U.S. Pat. No. 4,813,517 discloses a modular manifold brake hose end fitting for reducing the number of fittings in a vehicle brake line system, and published PCT Application No. WO 99/49256 discloses a brake pipe or tube having a reduced end portion projecting into a flexible hose which is compressed against the end portion by crimping a metal collar. The collar is confined on the tube by outwardly projecting circumferential ribs formed within the tube by compressing the tube axially.
The present invention is directed to an improved and simplified flexible brake line assembly which provides significant features and advantages. For example, a brake line assembly of the invention significantly reduces the cost of an assembly by eliminating expensive brass fittings, eliminating brazing and plating operations, eliminating female threaded fittings and xe2x80x9cbanjoxe2x80x9d-type fittings and simplifies the installation of the brake line assembly onto a motor vehicle. In addition, the brake line assembly of the invention minimizes potential leak paths, provides for convenient and rapid testing for high pressure leaks prior to shipment to a motor vehicle assembly plant, permits all of the brake line assemblies for a motor vehicle to be tied together to simplify handling, and further provides for installation of the assemblies to wheel brake calipers and other wheel brake cylinders and valves and manifolds with only one torque wrench.
In accordance with one embodiment of the invention, a hydraulic brake line assembly includes a section of high pressure flexible hose with concentric rubber-like tubes having surrounding or braided reinforcing fibers and with opposite end portions of the hose each receiving an inwardly forged and reduced end portion of a high pressure bendable steel tube. The end portion of each steel tube is forged or deformed to provide the axial cross sectional configuration and an outer diameter similar to a tubular nipple or eyelet. A metal sleeve or collar surrounds each end portion of the hose and the corresponding forged end portion of the steel tube and has a hole or bore for receiving the steel tube.
The collar is locked onto the tube by an inwardly tube deforming crimp or a threaded connection or by an outwardly projecting circumferential rib formed on the end portion of the tube when the reduced end portion of the tube is forged, and/or by a spring steel retaining washer on the tube. The metal collar is crimped to compress the end portion of the hose against the reduced and ribbed end portion of the tube and cooperates with the lock of the collar to the tube to form a connection or coupling between the tube and the hose having a substantial tensile strength over 400 pounds. The assembly of the collar and the connected end portions of the hose and tube may be encapsulated in an injected molded plastic body which is also molded with a mounting portion to facilitate attaching the assembly to a component of a motor vehicle.
The opposite end portion of the metal tube extending from each end portion of the flexible hose is formed with an outwardly projecting flare and receives an externally threaded or male flare nut. The flare nut may be threaded directly into a threaded port of a brake caliper or brake cylinder housing or valve body, and the port has a conical end surface for engaging the flared end of the metal tube. The metal tubes are bent to a predetermined configuration.
Other features and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.