Fluid-pressure and analogous brake systems – Pulsation neutralizers
Reexamination Certificate
2001-08-22
2002-12-17
Butler, Douglas C. (Department: 3683)
Fluid-pressure and analogous brake systems
Pulsation neutralizers
C303SDIG001, C303SDIG003, C303S122130, C060S413000, C138S030000
Reexamination Certificate
active
06494545
ABSTRACT:
This application is based on Japanese Patent Application No. 2000-290644 filed on Sep. 25, 2000, the contents of which are incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an accumulator and an apparatus for diagnosing the accumulator.
2. Discussion of Related Art
JP-A-9-123893 discloses an example of an apparatus for diagnosing an accumulator. The accumulator diagnosing apparatus disclosed in this publication includes (a) a high-pressure source arranged to deliver a pressurized working fluid; (b) a fluid-operated actuator operable with the pressurized fluid, (c) an accumulator disposed between the high-pressure source and the fluid-operated actuator and cooperating with the high-pressure source and the fluid-operated actuator to constitute a hydraulic system, (d) an accumulator-pressure detecting device operable to detect the pressure of the fluid in the accumulator, and (e) a diagnosing portion operable to determine that the hydraulic system is defective, if the fluid pressure detected by the accumulator-pressure detecting device is held lower than a predetermined lower limit for more than a predetermined length of time.
Although the known accumulator diagnosing apparatus is capable of detecting an abnormal state of the fluid pressure in the hydraulic system, as described above, this apparatus suffers from a problem that it is not capable of diagnosing the accumulator per se.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an accumulator diagnosing apparatus capable of diagnosing an accumulator per se. It is a second object of the invention to provide an apparatus including the accumulator diagnosing apparatus and capable of controlling a high-pressure source connected to the accumulator. It is a third object of the invention to provide the accumulator that can be diagnosed by the accumulator diagnosing apparatus. One of the above objects may be achieved according to any one of the following modes of the present invention, each of which is numbered like the appended claims and depends from the other mode or modes, where appropriate, to indicate and clarify possible combinations of elements or technical features. It is to be understood that the present invention is not limited to the technical features or any combinations thereof which will be described for illustrative purpose only. It is to be further understood that a plurality of elements or features included in any one of the following modes of the invention are not necessarily provided all together, and that the invention may be embodied without some of the elements or features described with respect to the same mode.
(1) A diagnosing apparatus for diagnosing an accumulator operable to store under pressure a pressurized fluid delivered from a high-pressure source and supply the pressurized fluid to a fluid-operated actuator for operating the fluid-operated actuator with the pressurized fluid, the apparatus comprising:
a pressure detecting device operable to detect a pressure of the pressurized fluid in the accumulator while the accumulator is placed in a fluid-tightly sealed state in which the accumulator is isolated from both the high-pressure source and the fluid-operated actuator; and
a diagnosing device operable to diagnose the accumulator on the basis of the pressure of the pressurized fluid detected by the pressure detecting device in the fluid-tightly sealed state of the accumulator.
The accumulator diagnosing apparatus constructed according to the above mode (1) of this invention is arranged to diagnose the accumulator for any abnormality or defect on the basis of the pressure of the fluid in the accumulator detected while the accumulator is isolated from both the high-pressure source and the fluid-operated actuator. The pressure detecting device is operable to detect the pressure of the pressurized fluid in the accumulator while the accumulator is placed in its fluid-tightly sealed state, so that the diagnosing device is capable of diagnosing the accumulator in the fluid-tightly sealed state of the accumulator.
For instance, the diagnosing apparatus is arranged such that when the fluid pressure detected by the pressure detecting device in the fluid-tightly sealed state of the accumulator is reduced below a predetermined threshold, the diagnosing device diagnoses the accumulator per se or its connector to be defective in its fluid tightness, or diagnoses a cut-off device connected to the accumulator, to be defective in its cut-off function. The cut-off device is operable to isolate the accumulator from the high-pressure source and the fluid-operated actuator.
(2) A diagnosing apparatus according to the above mode (1), wherein the accumulator includes:
a housing; and
a partition member disposed in the housing and cooperating with the housing to define an accumulator chamber (
84
;
162
) on one of opposite sides of the partition member, the accumulator chamber storing the pressurized fluid delivered from the high-pressure source,
and wherein the pressure detecting device includes an accumulator-chamber pressure sensor operable to detect the pressure of the pressurized fluid in the accumulator chamber.
The accumulator diagnosing apparatus according to the above mode (2) permits diagnosis of an accumulator of bladder type having the partition member in the form of a rubber bladder, an accumulator of bellow type having the partition member in the form of a metallic bellows, and an accumulator of piston type having the partition member in the form of a piston.
In the accumulator of bladder or bellows type in which the partition member is a bladder or bellows, a gas chamber charged with a pressurized gas is usually formed on the side of the partition member which is remote from the accumulator chamber. In the accumulator of piston type in which the partition member is a piston, the above-indicated gas chamber is formed or a biasing member such as a spring is disposed, on the side of the piston remote from the accumulator chamber. In the accumulator of bladder or bellow type, the gas pressure in the gas chamber is equal to the fluid pressure in the accumulator chamber while the accumulator is normal. Accordingly, the accumulator can be diagnosed on the basis of at least one of the fluid pressure in the accumulator chamber and the gas pressure in the gas chamber. The diagnosing apparatus for diagnosing the accumulator of piston type is preferably arranged to diagnose the accumulator on the basis of the fluid pressure in the accumulator chamber, since it is difficult or cumbersome to detect the biasing force of the biasing member.
(3) A diagnosing apparatus according to the above mode (2), wherein the accumulator includes a cut-off device having a first state in which the accumulator chamber is communicated with at least one of the high-pressure source and the fluid-operated actuator, and a second state in which the accumulator chamber is isolated from both the high-pressure source and the fluid-operated actuator.
In the accumulator diagnosing apparatus according to the above mode (3), the accumulator chamber can be placed in the fluid-tightly sealed state by placing the cut-off device in the second state. The fluid pressure in the accumulator chamber placed in the sealed state is detected to diagnose the accumulator. The provision of the cut-off device makes it possible to prevent the pressurized fluid from being unnecessarily discharged from the accumulator chamber, resulting in significant reduction in the amount of energy consumption by the high-pressure source, for example. The cut-off device may be provided within the housing of the accumulator, or outside the housing. In the former case, the cut-off device may be a sealing portion including a sealing member and a stopper portion of the housing which limits the amount of reduction of the volume of the accumulator chamber and on which the sealing member is fluid-tightly seated. In the latter case, the cut-off device may be disposed at a point of connecti
Mizukami Hiroshi
Nakamura Eiji
Butler Douglas C.
Kramer Devon
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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