Fluid handling – Systems – Supply and exhaust
Reexamination Certificate
2000-05-04
2001-11-13
Lee, Kevin (Department: 3753)
Fluid handling
Systems
Supply and exhaust
C137S884000, C060S452000, C060S420000
Reexamination Certificate
active
06314997
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a multiple valve apparatus which is preferably used for an industrial vehicle, such as a forklift truck, wherein a plurality of switching valve mechanisms can be stacked or attached together.
As a conventional multiple valve apparatus
100
of this kind, as shown in
FIG. 8
, there has been known a multiple valve apparatus which includes a priority valve mechanism
102
and a plurality of switching valve mechanisms
103
disposed on a downstream of the priority valve mechanism
102
. In this multiple valve apparatus, as shown in
FIG. 9
, a high pressure operating oil discharged from a hydraulic pump, not shown, is received at a port P, and for example, a flow of the high pressure oil is divided by the priority valve mechanism
102
, which is a constituent of the multiple valve apparatus, to a primarily flow ejected at a port PF for a steering operation, and a surplus flow thereof is guided through a parallel line
104
to reach input ports
132
of switching valves
131
built in the switching valve mechanisms
103
. And, the switching valves
131
are manually operated by operating levers L, so that an actuator, such as a tilt cylinder TS, a lift cylinder LS or the like, can be driven by the aforementioned surplus flow.
On the other hand, in the forklift truck in recent years, as an added value, there have been required an automatic horizontal stop function in which a mast can be automatically stopped in a horizontal condition, and an automatic elevation stop function in which the mast is stopped at a predetermined height. Also, in the forklift truck in recent years, in order to prevent collapse of loads or overturn of the vehicle, there has been proposed a function for limiting an operation speed of the actuator in a load condition in which it is moved near a stroke end or in which a balance of the vehicle is liable to be lost.
However, in regard to these demands, it has been considered that the multiple valve apparatus with the manually operated conventional type can not be adopted. Thus, there has been developed a multiple valve apparatus with an automatically operated type by using an electromagnetic proportional valve in the switching valve mechanism.
However, these devices are of high grade, and have a disadvantage in the aspect of a cost thereof. Also, simply, there has been considered a method of unloading the discharge oil from the pump completely before the discharge oil is guided to the multiple valve apparatus. However, in this method, since the function of the priority valve mechanism is stopped while the automatic stop function is operated, there is caused an inconvenience such that a supply of the high pressure operating oil to the steering or the like is cut off.
The present invention has been made in order to solve these problems, and in view of the fact that a supply of the operating oil to each switching valve mechanism is operated through the parallel line communicating with a supply flow output port of the priority valve mechanism, and a main object of the invention is to provide a multiple valve apparatus which is provided with an urgent stop valve which is capable of disconnecting and connecting between the parallel line and a tank line, wherein in a predetermined condition where the automatic stop function is required, the urgent stop valve is opened to allow the supply of the operating oil only to the switching valve mechanism to eject by a simply structure, so that the automatic stop function for the actuator, such as a cylinder, can be achieved.
Another object of the invention is to provide a multiple valve apparatus, wherein a supply of the operating oil only to the switching valve mechanism is limited also by the simple structure, so that an automatic deceleration of the actuator, such as a cylinder, can be achieved.
Further objects and advantages of the invention will be apparent from the following description of the invention.
SUMMARY OF THE INVENTION
To achieve the aforementioned objects, the present invention provides a multiple valve apparatus, which is formed of a priority valve mechanism for dividing a supplied operating liquid into a priority flow and a surplus flow and discharging the same; one or a plurality of switching valve mechanisms including a switching valve therein and being stacked on the priority valve mechanism; a parallel line for guiding the surplus flow discharged from the priority valve mechanism to each input port of each switching valve, and an urgent stop valve for communicating the parallel line with a tank line in a predetermined condition.
Also, in the multiple valve apparatus of the invention, a supplied operating fluid is divided by the priority valve mechanism into the priority flow and the surplus flow, and the surplus flow discharged from the priority valve mechanism is guided to input ports of switching valves built in one or plural switching mechanisms. The multiple valve apparatus as structured above is provided with an urgent valve formed between the parallel line and the tank line communicating with the tank, and by opening the urgent valve, the parallel line is allowed to communicate with the tank line through a flow amount control valve disposed on the downstream side of the urgent valve.
In this multiple valve apparatus, without deteriorating or losing the function of the priority valve mechanism, and without using the high-grade and expensive member, such as electromagnetic proportional valve, an automatic stop function or automatic deceleration function of the actuator, which is necessary for a forklift truck or the like, can be achieved by a simple and inexpensive structure, such as interposing the urgent stop valve or the urgent valve in the parallel line.
The aforementioned predetermined condition is set in accordance with a horizontal position or an elevated position in the industrial vehicle, for example a forklift truck, and generally obtained by the condition detecting means, such as position sensor. However, in order to correspond to these structures optimally and to simplify the structure, it is preferable that the urgent stop valve or urgent valve is electromagnetically driven by the information form the condition detecting means.
Also, by simply adding an urgent stop valve block or urgent valve block to the existing multiple valve apparatus, the present invention can be achieved easily and at an extremely low cost. In order to obtain various effects such as introducing the apparatus to the users, it is preferable that the urgent stop valve or urgent valve is accommodated in the urgent valve block having the attachment compatibility with the switching valve mechanism.
REFERENCES:
patent: 5203678 (1993-04-01), Sugiyama et al.
patent: 5735305 (1998-04-01), Ikei et al.
patent: 6089248 (2000-07-01), Rost
patent: 6098403 (2000-08-01), Wilke
Kanesaka & Takeuchi
Lee Kevin
Shimadzu Corporation
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