BRIEF DESCRIPTION OF THE DRAWINGS
The invention, together with additional objectives, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which:
FIG. 1 is a cross-sectional view of a brake fluid pressure controlling unit according to one embodiment of the present invention;
FIG. 2 is a cross-sectional view of a brake fluid pressure controlling unit according to another embodiment of the present invention;
FIG. 3 is cross-sectional view of a brake fluid pressure controlling unit according to another embodiment of the present invention; and
FIG. 4 is a circuit diagram of a brake fluid pressure controlling system for a vehicle, which employs a brake fluid pressure controlling unit according to another embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
An embodiment of the present invention will be described below with reference to the accompanying drawing of FIGS. 1 to 4. FIG. 1 shows one embodiment of the present invention. A brake fluid pressure controlling unit 1 for a vehicle of the present embodiment includes a metal fluid pressure controlling block 2 and a controller 3.
The fluid pressure controlling block 2 internally includes a first fluid pressure circuit and a second fluid pressure circuit (both not shown in FIG. 1). Here, the first fluid pressure circuit has one end connected to one of pressure chambers of a tandem master cylinder, and has other two branched ends connected to the corresponding wheel cylinders of two front wheels of the vehicle (longitudinally sprit) or to a right front wheel and a left rear wheel of the vehicle (diagonally sprit). Also, the second fluid pressure circuit has one end connected to another one of the pressure chambers of the master cylinder, and has other two branched ends connected to wheel cylinders of other remained two wheels. Also, the fluid pressure controlling block 2 includes well-known components for controlling fluid pressure of each wheel cylinder, such as solenoid valves 18, which increase and decrease fluid pressure of wheel cylinders when required depending on a command from an electronic control unit. Components assembled into the fluid pressure controlling block 2 will be described in detail later.
The fluid pressure controlling block 2 defines a fluid chamber 4 therein, which is connected with the fluid pressure circuit, and an electronic component 5 (e.g., a pressure sensor for sensing a brake fluid pressure shown in FIG. 1) is mounted on the fluid pressure controlling block 2. Here, the electronic component 5 has a sensing portion at an end that faces the fluid chamber 4, and a gap between an periphery of the end portion of the electronic component 5 and the fluid chamber 4 is fluid-tightly sealed.
The controller 3 includes a resin case 6, a resin cover 7, and a circuit board 9. Here, the case 6 covers components on the fluid pressure controlling block 2, and the cover 7 is attached to the case 6. Alternatively, the cover 7 may be made of metal, instead of the resin. Also, the cover 7 receives an electronic control unit (ECU) 8, which is mounted on the circuit board 9. The case 6 includes a metal sleeve 10 embedded therein for reinforcing a mounting bore. The metal sleeve 10 receives a threaded member 11, and the threaded member 11, which is inserted into the metal sleeve 10, fixes the case 6 to the fluid pressure controlling block 2. The cover 7 is removably attached to the case 6 through a fastening element (not shown), such as a threaded member.
The circuit board 9 is provided with a control circuit (not shown), and the control circuit has certain parts, to which terminals T of components mounted on the fluid pressure controlling block 2, such as the electronic component 5 and the solenoid valves 18, are connected. The circuit board 9 has a grounded portion (ECU GND) EG, which is electrically connected with a connector (not shown), which is connected with a battery of the vehicle through a harness.
Also, the case 6 has an electric conductor 12 (e.g., a bus bar in FIG. 1). The electric conductor 12 has one end connected with the grounded portion EG of the circuit board 9 in the cover 7, and has another end electrically connected with the fluid pressure controlling block 2 through the metal sleeve 10 and the threaded member 11. Due to this structure, the fluid pressure controlling block 2 and the grounded portion EG of the circuit board 9 are electrically connected through the electric conductor 12 such that the fluid pressure controlling block 2 and the grounded portion EG has the same electrical potentials. Thus, a noise is not likely to be induced to the electronic component 5 and therefore, even an electronic component, which has relatively small noise resistance (e.g., a normal electronic component with a normal noise resistance), can be employed in a severe noise environment. Conduction to the grounded portion EG within the cover 7 can advantageously shorten the electric conductor 12. This can also brings advantages in productivity, a parts control, and cost in manufacture.
A capacitor 13 may be provided between the electric conductor 12 and the grounded portion EG of the circuit board 9. In a case, where the capacitor 13 is provided, the capacitor 13 selectively permits a noise element to flow.
It is noted that the electric conductor 12 shown in FIG. 1 has a bending portion 12a at the another end thereof, and the bending portion 12a and the case 6 are fastened together to the fluid pressure controlling block 2 though the threaded member 11, which is screwed into the fluid pressure controlling block 2. Thus, work units (e.g., manhour) for assembling the controller 3 can be advantageously reduced. Further, the metal sleeve 10 has one end in contact with the electric conductor 12 and another end in contact with the fluid pressure controlling block 2. In this structure, because the electric conductor 12 can be electrically connected with the fluid pressure controlling block 2 through the metal sleeve 10 and the threaded member 11, a preferable electrical connection can be achieved without extending the electric conductor 12 to contact the fluid pressure controlling block 2.
In addition to the above, in a case, where a bus bar of a rigid body as shown in the drawing is employed as the electric conductor 12, the electric conductor 12 is easily mounted. In a case where a flexible harness is used as an electric conductor fixed through a threaded member, a terminal needs to be attached to the flexible harness. However, the bus bar eliminates the labor hour for this assembly.
The electric conductor 12 and the case 6 are not essentially required to be fixed together in the present invention. In a case of use of an external fastening type case, in which the threaded member 11 fastens the case 6 to the fluid pressure controlling block 2 by externally fastening as shown in FIG. 2, the electric conductor 12 may be solely fastened to the fluid pressure controlling block 2 by a threaded member 14.
The electric conductor 12 may alternatively press contact the fluid pressure controlling block 2 as shown in FIG. 3 such that the electric conductor 12 can be electrically connected with the fluid pressure controlling block 2. In a brake fluid pressure controlling unit 1 shown in FIG. 3, the electric conductor 12 is configured by a bus bar, and extends through the case 6 to be assembled thereto. Here, the electric conductor 12 has a contacting portion 12b at the another end thereof such that the contacting portion 12b is pressed against the fluid pressure controlling block 2. Here, the contacting portion 12b is made by bending and is resiliently deformable. In this structure, a work unit for screwing the electric conductor 12 can be eliminated, and thus operability can be improved.
Next, an example of a circuit configuration of a brake fluid pressure controlling system for a vehicle will be shown in FIG. 4. The brake system shown in FIG. 4 has an electronic stability control (ESC) function, and includes a brake pedal 21, a tandem master cylinder 24, the above brake fluid pressure controlling unit 1, and wheel cylinders 27a to 27d for respective wheels. Here, the tandem master cylinder 24 has a reservoir 23 and a fluid pressure booster 22, which augments a brake operation force applied by a driver.
In the brake fluid pressure controlling unit 1, the fluid pressure controlling block 2 (see FIG. 1) internally has fluid pressure circuits 15, 16, which are connected to respective pressure chambers of the master cylinder 24. A linear control valve 17 is assembled to each of the fluid pressure circuits 15, 16. Boost solenoid valves 18A are assembled to branch passages of each fluid pressure circuit downstream of a branch point d (e.g., in the present embodiment of the present invention, “downstream” means a side closer to the wheel cylinders). Furthermore, a vacuum solenoid valve 18B is assembled to a circuit connected to each branch passage downstream of the boost solenoid valve 18A.
Here, the fluid pressure controlling block 2 includes reservoirs 20, pumps 25, and a motor 26. Here, working fluid (brake fluid) discharged from the vacuum solenoid valves 18B is temporally reserved in each reservoir 20. Also, each pump 25 pumps the working fluid accumulated in each reservoir 20 to recycle the working fluid in the corresponding fluid pressure circuit. It is noted that when the master cylinder is not in operation and the reservoir 20 has no available fluid accumulated therein, the working fluid in the reservoir 23 is pumped via a solenoid valve 19 to the corresponding fluid pressure circuit. The motor 26 drives these pumps 25. In FIG. 4, each of check valves 28 is arranged in parallel with the corresponding linear control valve 17, and each of check valves 29 is arranged in parallel with corresponding boost solenoid valve 18A. Also, each of check valves 30 can be alternatively assembled inside the corresponding pump 25.
Also, in the above embodiment, the fluid pressure controlling block includes single electronic component 5 (pressure sensor) for sensing the fluid pressure in the fluid pressure circuit 15 upstream of the linear control valve 17. However, two or three of pressure sensors may be alternatively provided by locating additional ones at other parts. Thus, the present invention can be more effectively applied to the above brake system, where a fluid pressure controlling block of a brake fluid pressure controlling unit includes two or three pressure sensors, which are one example of the electronic component.
In the above embodiment, the pressure sensor is described as the electronic component mounted on the fluid pressure controlling block. However, other information for the fluid pressure control (e.g., acceleration of the vehicle) other than the fluid pressure may be alternatively sensed by a sensor. Then, this information may be received by the electronic control unit 8. Even in this case, when the structure described in the present invention is applied, abnormal control can also be effectively limited. Otherwise, because the sensor, which is mounted on the fluid pressure controlling block to sense the other information other than the fluid pressure, may abnormally operate due to a noise, the electronic control unit 8 may receive erroneous information, thereby degrading reliability of the control.
Additional advantages and modifications will readily occur to those skilled in the art. The invention in its broader terms is therefore not limited to the specific details, representative apparatus, and illustrative examples shown and described.