Brake fluid pressure controller

Abstract: A brake fluid pressure controller (1) including a hydraulic unit (2) having a housing (3) and a pump mounted in the housing (3), and a motor (4) for the pump having an end cover and an output shaft (5) received in a hole formed in the housing (3), and being coupled to the housing (3) by means of a plurality of through bolts (7) extending through the end cover of the motor (4) and threaded into the housing (3), and a seal member (10) sandwiched between opposite surfaces of the motor (4) and the housing (3) to seal the space around the output shaft (5) and the space around each through bolt (7), the seal member (10) being in the form of a rubber packing comprising a large-diameter annular seal portion (11) surrounding the output shaft (5), and small-diameter annular seal portions (12) integrally formed along the outer edge of the large-diameter annular seal portion (11).

Description: The present invention relates to a brake fluid pressure controller with a motor-driven hydraulic pump necessary for antilock control and track control of vehicle wheels, and more specifically to a brake fluid pressure controller having an improved structure for sealing between the pump-driving motor and the housing of a hydraulic unit coupled to the motor, according to the preamble of the claim. This type of brake fluid pressure controller has an electric motor for driving the hydraulic pump mounted in the housing of the hydraulic unit. The motor is directly mounted on the housing. As disclosed in prior art (EP 0488260A1), the motor is usually fixed to the housing by inserting through bolts through the rear end cover of the motor and the space between its rotor and yoke, and tightening them into the housing. This brake fluid pressure controller is mounted in the engine room of a car. Especially if it is mounted at a lower part of the engine room, high waterproofness is required. It is possible to completely seal the rear portion of the motor by forming the end cover of the motor and the cylindrical portion of the yoke as an integral member, or by welding the end cover to the cylindrical portion of the yoke. What is difficult is to seal the contact area between the housing of the hydraulic unit and the motor. Heretofore, in order to completely seal the contact area and thus to improve the waterproofness of the entire controller, the opposite surfaces of the motor and the housing were brought into contact with each other after increasing their flatness by cutting. But with this method, it is practically impossible to perfectly seal the contact area because it is difficult to obtain flat surfaces by cutting. Thus, water may infiltrate into the contact area between the housing and the motor, and then into the motor through gaps around the through bolts and the output shaft of the motor, or into the housing through a hole formed in the housing to receive the output shaft of the motor. If more positive waterproofness is required, as shown in Fig. 2, it was necessary to provide seal rings 8 such as O-rings to seal any gap around the output shaft 5 of the motor and the through bolts 7 for coupling the motor 4 to the housing 3. If the seal rings 8 are used, it is necessary to form seating grooves 9 by cutting to receive the seal rings 8 in the housing 3 of the hydraulic unit 2 to protect the seal rings by limiting their interference. Further, it was a troublesome and timeconsuming job to mount a plurality of seal rings one by one. Since many rings are used, some of them are frequently omitted by oversight. Further prior art are gaskets (US-4 101 138 A) and flat packing elements (WO 94/10738, EP 269552A1) An object of the present invention is to provide a brake fluid pressure controller which has a seal member which can be mounted easily and reliably. This problem is solved by the characterizing part of the claim:-a seal member is sandwiched between opposite surfaces of the motor and the housing to seal the space around the output shaft and the space around the each through bolt, the seal member being in the form of a rubber packing comprising a large-diameter annular seal portion surrounding the output shaft, and small-diameter annular seal portions integrally formed along the outer edge of the large-diameter annular seal portion, each surrounding the respective through bolt. Since the rubber packing is not so thick, it is not necessary to form so deep a recess to limit the interference of the packing. Such a shallow recess is formed in the front end cover of the motor by pressing. The rubber packing may have a plurality of protrusions on one side thereof which are received in holes formed either in the front end cover of the motor or in the housing of the hydraulic unit. The protrusions make easy the positioning of the packing. The use of the single, one-piece seal member leads to reduced number of assembling steps. It is improbable that an assembly worker may forget to mount such a one-piece seal member on the controller. By forming the recess for receiving the rubber packing in the front end cover of the motor by pressing, it is possible to eliminate the necessity of forming seating grooves by cutting, which takes a lot of trouble and thus money. By providing the rubber packing with protrusions and fitting them in holes formed in the hydraulic unit or the motor, the rubber packing can be set in position beforehand and is less likely to drop out once fitted in position, so that the motor can be coupled more easily to the hydraulic unit. Other features and objects of the present invention will become apparent from the following description made with reference to the accompanying drawings, in which: Fig. 1A is a partially cutaway side view showing the state before the rubber packing is mounted on the housing of the hydraulic unit; Fig. 1B is a partially cutaway enlarged side view showing the state after it is mounted on the housing; Fig. 2A is a side view of a brake fluid pressure controller having a conventional sealing structure; and Fig. 2B is a sectional view of the same illustrating how the seal ring is mounted. Fig. 1A shows a brake fluid pressure controller 1 embodying the present invention. It comprises a hydraulic unit 2 and a motor 4 directly coupled to the hydraulic unit 2. The hydraulic unit 2 has a hydraulic pump mounted in its housing 3. It also has a fluid passage connecting the master cylinder with wheel brakes, a fluid passage connecting the wheel brakes with a buffer chamber, a fluid passage connecting the pump outlet with the master cylinder, and solenoid valves for increasing, holding and reducing wheel brake pressures by opening and closing the fluid passages. The hydraulic unit 2 itself is conventional, and may further include a fluid flow control valve in the housing 3. The abovementioned buffer chamber may also be provided in the housing 3. In Fig. 1A and all the other figures, the elements in the housing are not shown. The motor 4 has its output shaft 5 received in a hole formed in the housing 3, and is coupled to the hydraulic unit 2 by through bolts 7 (in the embodiment, two through bolts are provided in a diametrically opposite relation) which are inserted through a rear end cover of a yoke 6 and the space between the cylindrical portion of the yoke and the rotor and threadedly engaged in threaded holes formed in the housing 3. The motor 4 and the housing 3 abut each other through a rubber packing 10, the main characterizing feature of the present invention. The rubber packing 10 comprises a large-diameter, annular seal portion 11 for sealing the space around the output shaft 5, small-diameter annular seal portions 12 integrally formed along the outer edge of the seal portion 11 to seal the space around the individual bolts 7, and a total of two protrusions 13 provided on one side of the packing 10 facing the housing 3 at a position between the annular seal portion 11 and the annular seal portions 12. As shown in Fig. 1, protrusions 13 may be formed on the side of the packing facing the motor 4 to press-fit them into holes 14 formed in the front end cover of the motor. According to the invention a recess 15 is formed by pressing in the front end cover of the motor to receive the rubber packing 10 therein. With this arrangement, it is possible to prevent the rubber packing from being pressed too tightly.

Claims: Brake fluid pressure controller (1) comprising a hydraulic unit (2) having a housing (3) and a pump mounted in said housing (3), and a motor (4) for driving said pump, said motor (4) having an end cover and an output shaft (5) received in a hole formed in said housing (3), and being coupled to said housing (3) by means of a plurality of through bolts (7) extending through the end cover of said motor (4) and threaded into said housing (3), and a seal member sandwiched between opposite surfaces of said motor (4) and said housing (3) to seal the space around said output shaft (5) and the space around said each through bolt (7), said seal member being in the form of a rubber packing (10), characterized in that a large-diameter annular seal portion (11) of said packing (10) surrounds said output shaft (5), and small-diameter annular seal portions (12) of said packing (10) are integrally formed along the outer edge of said large-diameter annular seal portion (11), each surrounding said respective through bolt (7), and in that said motor (4) has a recess (15) formed by pressing in the end face thereof facing said housing (3), said rubber packing (10) being received in said recess (15).

Inventors: NOKUBO SEIJI, NOKUBO, SEIJI, NOKUBO, SEIJI, C/O ITAMI WORKS OF
Applicants: SUMITOMO ELECTRIC INDUSTRIES, SUMITOMO ELECTRIC INDUSTRIES, LTD.
Application year: 1995
Main classification: B60T8
IPC codes: B60T8, B60T17, H02K7, F04B17, H02K5