Directional control valve

An improvement to reduce the size of a directional control valve by providing a plurality of pilot spool valves in a single valve casing. A plurality of valve mechanisms are juxtaposed in a monolithic valve casing by individually inserting valve members in a plurality of parallel valve bores provided in the valve casing. A plurality of cylinders corresponding to the valve bores are pierced in an intermediate plate mounted on the valve casing from that face which comes in contact with the valve casing. The cylinders communicate with each other by means of grooves cut in the aforementioned contacting face and open into the atmosphere through a relief port. The adjoining cylinders are thus brought closer, and the valve bodies are driven by pilot fluid pressure that act on the pistons fitted in the individual cylinders.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a directional control valve for use with 
industrial machines operated by fluid pressure. 
2. Description of the Prior Art 
With small-sized directional control valves of known types, one valve 
casing generally contains one each valve mechanism. To mount a plurality 
of directional control valves on a base or the like, therefore, a 
corresponding number of mounting bolts and receiving tapped holes in the 
base have been required. 
The size of such conventional directional control valves has been difficult 
to reduce beyond a certain limit because each valve must have a large 
enough casing to provide one or more mounting holes therein. It has also 
been difficult to reduce the size of their mounting bases since 
appropriate intervals must be left between the individual valve casings 
mounted thereon. 
Miniaturization of such directional control valves can be achieved to a 
certain extent by juxtaposing a plurality of valve mechanisms in one valve 
casing, thereby reducing the space for the mounting holes that have 
conventionally been required by each valve and also the intervals between 
the individual valve mechanisms. Even then, valve mechanisms cannot be 
placed too close to each other for avoiding leakage of hydraulic fluid 
flowing therebetween. 
SUMMARY OF THE INVENTION 
A principal object of this invention is to provide a directional control 
valve of smaller size than ever that is obtainable by reducing the size of 
a known directional control valve comprising a plurality of valve 
mechanisms contained in a single valve casing for the purpose of space 
saving through the improvement of valve structure. 
In a spool valve operated by the fluid pressure supplied from a pilot 
valve, the piston thereof is generally made to have a larger diameter than 
the valve body because of the need to obtain large enough force to drive 
the valve body. In attempting to achieve valve size reduction by 
containing a plurality of such pilot-driven valve mechanisms in a single 
valve casing, one of the major problems to be solved is how to place the 
pistons that drive the individual valve bodies close to each other. 
Another object of this invention is to provide a directional control valve 
having an intermediate plate in which cylinders to contain the pistons are 
spaced away from each other only at very small distances. 
Still another object of this invention is to provide a directional control 
valve which comprises a valve casing, which is substantially a rectangular 
solid in shape, having a plurality of parallel valve bores pierced between 
a pair of opposite faces thereof. Another series of bores communicating 
with said valve bores are also pierced from one face of the rectangular 
solid that is parallel to the valve bores, thereby providing a power 
output port, a pressure exhaust port and a pressure supply port and, at 
the same time, forming a power output chamber, a pressure exhaust chamber 
and a pressure supply chamber in the valve bores. This design not only 
greatly simplifies the structure of a valve block but also facilitates the 
manufacturing thereof. 
Yet another object of this invention is to provide a directional control 
valve that can be made with high efficiency through a reduction in the 
number of working processes in the making of a valve casing by bringing 
the pressure supply chambers of a plurality of juxtaposed valve mechanisms 
into communication with each other to provide a common pressure supply 
chamber. 
The foregoing objects of this invention are achieved as follows: A 
directional control valve according to this invention comprises a 
monolithic valve casing pierced with a plurality of parallel valve bores 
and a plurality of pilot-driven valve mechanisms. Each valve mechanism has 
spool valves that are inserted in the valve bores and switched by pistons 
driven by pilot fluid pressure between one position where the pressure 
fluid fed from a pressure supply port is discharged to a power output port 
and another position where the pressure fluid from the power output port 
is discharged to a pressure exhaust port. The valve casing is a block 
having the plurality of parallel valve bores pierced between a pair of 
opposite faces thereof and bores to provide the pressure supply, power 
output and pressure exhaust ports pierced in the direction perpendicular 
to said series of valve bores. An intermediate plate is fastened to one 
end surface of the valve casing where the valve bores open. The 
intermediate plate has a plurality of cylinders corresponding to the valve 
bores and opening on that side thereof which faces the valve casing. The 
cylinders are brought into communication with each other by grooves cut on 
said side of the intermediate plate facing the valve casing, while being 
opened into the atmosphere through a relief port provided in the outer 
wall of the intermediate plate. A piston is slidably fitted in each 
cylinder and brought in contact with the end surface of a valve body 
inserted in the corresponding valve bore, with a pilot chamber being 
provided on the inner-end side of the cylinder. A plurality of pilot 
valves to supply pilot pressure fluid to the pilot chambers are provided 
on the intermediate plate. 
In the directional control valve of this invention just described, a valve 
casing has a plurality of valve bores pierced side by side, in each of 
which an independent valve body is inserted. Thus, a plurality of valve 
mechanisms are juxtaposed in a single valve casing. The partition walls 
between the adjoining valve bores need not have any greater strength than 
is required for withstanding the pressure of a fluid flowing into such 
bores. The partition walls need not be as strong as the outer walls of the 
valve bores at both ends that have to keep up the shape of the whole 
casing and withstand forces applied from outside. Accordingly, this design 
permits a remarkable size reduction, compared with an assembly which 
comprises a plurality of conventional directional control valves each of 
which consists of a valve mechanism contained in one each valve casing. 
While a plurality of parallel valve bores are pierced in a single valve 
casing, a pressure support port, a power output port and a pressure 
exhaust port are provided in the direction perpendicular to said bores. 
This design not only simplifies the structure of the valve casing but also 
facilitates its manufacturing. 
A directional control valve of this invention also has an intermediate 
plate fastened to one end surface of the valve casing thereof. The 
intermediate plate has a plurality of cylinders corresponding to said 
valve bores, with the cylinders being pierced from that side thereof which 
faces the valve casing. The cylinders are brought into communication with 
each other by grooves cut on said side of the intermediate plate facing 
the valve casing, while being opened into the atmosphere through a relief 
port provided in the outer wall of the intermediate plate. This design is 
also conducive to reducing the overall size of the valve. 
In reducing to a minimum the size of a valve casing in which a plurality of 
parallel valve bores are provided to insert a corresponding number of 
spool valves driven by pilot fluid pressure, one of the major problems 
that confront is how to reduce the intervals between the individual 
cylinders because there is also the general need of making the diameter of 
such pistons somewhat larger than the diameter of the valve bodies in 
order to derive the required valve driving force from the pilot fluid 
pressure. 
On the other hand, the aforementioned intermediate plate, which has a 
plurality of cylinders pierced from that end which comes in contact with 
the valve casing, eliminates the need to provide sealing between the 
individual cylinders because the cylinders communicate with each other by 
means of the connecting grooves and opens into the atmosphere through the 
relief port. This permits bringing the adjoining cylinders much closer to 
each other than in a valve casing of the known type in which cylinders are 
separated from each other by means of sealing material so as to keep them 
immune to the adverse effect of pressure. Provision of the pilot chamber 
at the inner end of the cylinder also helps keep up the strength of the 
cylinder wall against the pressure exerted from the pilot chamber. 
The aforementioned and other objects, structures and effects of this 
invention will become apparent from the following detailed description of 
preferred embodiments of the invention given with reference to the 
accompanying drawings. The examples given below are simply preferred 
embodiments to which this invention is by no means limited.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a first embodiment of this invention which comprises a valve 
casing 1 pierced through with three vertical valve bores 2 each of which 
has a pressure supply chamber 3 in the middle thereof, with power output 
chambers 4a and 4b and pressure exhaust chambers 5a and 5b symmetrically 
disposed on both sides of said pressure supply chamber 3. As is clearly 
shown in FIG. 2 (A), the pressure supply chambers 3 of the individual 
valve bores communicate with each other to constitute a common pressure 
supply chamber. 
A valve body 6 is slidably inserted in each of the valve bores 2 whose both 
ends are sealed by flanges 7a and 7b each carrying an O-ring thereon. 
Circular valve portions 8a, 8b, 8c and 8d are provided at intervals 
between the flanges 7a and 7b, with a sealing member 9 being fitted in a 
groove cut around the periphery of each valve portion. The circular valve 
portions 8a, 8b, 8c and 8d on the valve body 6 are disposed in such a 
manner that the power output chamber 4a and pressure exhaust chamber 5a 
and the pressure supply chamber 3 and power output chamber 4b are 
respectively brought into communication while the pressure supply chamber 
3 and power output chamber 4a and the power output chamber 4b and pressure 
exhaust chamber 5b are respectively disconnected on the return stroke of 
the valve body 6. Meanwhile, the pressure supply chamber 3 and power 
output chamber 4a and the power output chamber 4b and pressure exhaust 
chamber 5b are respectively brought into communication while the pressure 
supply chamber 3 and power output chamber 4b and the power output chamber 
4a and pressure exhaust chamber 5a are respectively disconnected on the 
driving stroke of the valve body 6. 
A partition wall 1a between the adjoining valve bores 2 in the valve casing 
1 serves its purpose if it is strong enough to withstand the sliding 
motion of the valve body 6 and the pressure of fluid flowing into the 
valve bores 2 on both sides thereof. Unlike the outer walls 1b defining 
the valve bores 2 at both ends, the partition wall 1a need not have such 
strength as is great enough to maintain the overall shape of the assembly 
or to withstand any force exerted from outside. This permits drastically 
reducing the thickness of the individual partition walls 1a and, 
therefore, making the whole valve casing 1 much smaller than one that 
contains three independent directional control valves placed side by side. 
The valve casing 1 is made of metal or synthetic resin that is formed into 
a block shaped substantially like a rectangular solid, with a plurality of 
parallel valve bores 2 pierced between a pair of opposite faces thereof. A 
required number of bores extending perpendicularly to and reaching each of 
said valve bores 2 are pierced from a face that is parallel thereto, 
whereby not only a plurality of power output ports 16a and 16b and 
pressure exhaust ports 17a and 17b and a single pressure supply port 15 
but also said power output chambers 4a and 4b, pressure exhaust chambers 
5a and 5b and pressure supply chamber 3 in the valve bores are formed. To 
provide the power output chambers 4a and 4b and pressure exhaust chambers 
5a and 5b at the same time, the power output ports 16a and 16b and the 
pressure exhaust ports 17a and 17b are made larger than the valve bore 2 
(see FIG. 2 (B)), while the size of the pressure supply port 15 is equal 
to or larger than the common pressure supply chamber 3 (see FIG. 2 (A)). 
All bores and ports, which are provided either by machining from outside 
the valve casing 1 or by die-casting, extend inward from the surface of 
the valve casing, either straight or, at least, growing progressively 
smaller in diameter toward the center. This permits greatly simplifying 
the design of the valve casing and facilitates its manufacturing. 
As is shown in FIG. 3, the pressure supply port 15 communicating with the 
common pressure supply chamber 3 shared by the individual valve ports 2, 
the multiplicity of power output ports 16a and 16b respectively 
communicating with the power output chambers 4a and 4b in each valve port 
2 and the multiplicity of pressure exhaust ports 17a and 17b respectively 
communicating with the pressure exhaust chambers 5a and 5b therein are 
pierced from the surface of the valve casing 1. Mounting holes 18 for use 
in fixing the valve casing 1 on a base or the like are provided at the 
four corners thereof. Also, tapped holes 19 for use in attaching an 
intermediate plate 21 to be described later are provided in one end 
surface of the valve casing 1. 
The embodiment shown in FIG. 3 has the multiplicity of pressure exhaust 
ports 17a and 17b which respectively communicate with the pressure exhaust 
chambers 5a and 5b in each valve mechanism. But the number of such 
pressure exhaust ports may be reduced to two, as with the pressure supply 
port 15 shown in FIG. 2 (A); in which case a first common pressure exhaust 
port is shared by the pressure exhaust chambers 5a of the individual valve 
mechanisms and a second common pressure exhaust port is shared by the 
pressure exhaust chambers 5b of the individual valve mechanisms. 
To one end of said valve casing 1 is attached a common keep plate 11 using 
bolts or other appropriate fastening means, with a sheet-formed sealing 
material interposed therebetween. A return spring chamber 13 is provided 
between the keep plate 11 and the flange 7b of each valve body 6. The 
individual return spring chambers 13 communicate with each other by means 
of communicating passages 12 provided on the keep plate 11. Each chamber 
13 contains a spring 14 that urges the valve body 6 in the returning 
direction. If necessary, fluid pressure may be supplied to the return 
spring chamber 13 so that a greater urging force is generated through the 
combination of the spring force and fluid pressure. 
The intermediate plate 21 is fastened to one end surface of the valve 
casing 1 through a sheet-formed packing 20 by means of bolts screwed into 
said tapped holes 19. The intermediate plate 21 has three cylinders 22 
pierced from that side thereof which comes in contact with the valve 
casing 1. The cylinders 22 communicate with each other by means of grooves 
23 cut in the contacting surface of the intermediate plate 21 and open 
into the atmosphere through a relief port 24 provided in the outer wall of 
the intermediate plate 21. A piston 25 slidably fitted in each cylinder 22 
comes in contact with the end surface of the valve body 6, defines a pilot 
chamber 30 at the inner end of the cylinder 22, and pressed in the 
returning direction by the valve body 6 that is urged by said spring 14. 
In reducing to a minimum the size of the valve casing 1 in which a 
plurality of parallel valve bores 2 are provided to insert a corresponding 
number of spool valves, one of the major problems that confront is how to 
reduce the intervals between the individual cylinders 22 because there is 
also the general need of making the diameter of the pistons 25 somewhat 
larger than the diameter of the valve bodies 6 in order to obtain the 
required valve driving force. 
In this respect, the aforementioned intermediate plate 21 is designed to 
effectively reduce the intervals between the individual cylinders. The 
intermediate plate 21, which has a plurality of cylinders 22 pierced from 
that end thereof which comes in contact with the valve casing 1, 
eliminates the need to provide sealing between the individual cylinders 22 
because the cylinders communicate with each other by means of the 
connecting grooves 23 and opens into the atmosphere through the relief 
port 24. This permits bringing the adjoining cylinders much closer to each 
other than in a valve casing of the known type in which cylinders are 
separated from each other by means of sealing material so as to keep them 
immune to the adverse effect of pressure. In such a conventional valve 
casing, each partition wall must have a thickness of 2 mm minimum since 
there is the need to hold the sealing material between the adjoining walls 
against the force exerted by pressurized fluid. Provision of the pilot 
chamber 30 at the inner end of the cylinder 22 also helps keep up the 
strength of the cylinder wall against the pressure exerted from the pilot 
chamber 30. As a consequence, adjoining cylinders can be brought close to 
each other within such a limit that the pressure from the pilot chamber 30 
is safely withstood. Even if adjoining cylinders are brought close enough, 
it is only in a limited portion (on the line connecting the centers of the 
two cylinders) of a very small area that the intervening wall becomes very 
thin. Therefore, the wall can retain considerably great strength. 
Three solenoid pilot valves 31 are mounted on the intermediate plate 21, 
with a sheet-formed sealing material interposed therebetween. Each pilot 
valve 31 has a valve chamber 33 that communicates with a pilot chamber 30 
in each cylinder 22 by means of a connecting port 26 pierced through the 
end wall of the intermediate plate 21. 
The pilot valve 31 has through holes 32a and 32b provided at both ends of 
the valve chamber 33, with the inner ends of the through holes 32a and 32b 
serving as valve seats 33a and 33b. A movable valve 35 having valve 
members 34a and 34b at both ends thereof is inserted in the valve chamber 
33. The movable valve 35 is normally urged toward the valve seat 33b by a 
spring 36 provided in the valve chamber. When an exciting coil 37 around 
the movable valve 35 is energized, the movable valve 35 constituting an 
armature is attracted to a stator core 38 surrounding the through hole 32a 
against the force of the spring 36. 
While the other end of the through holes 32a opens into the atmosphere, the 
other end of the through holes 32b communicates with a common pilot 
pressure passage 27 provided in the intermediate plate 21. The pilot 
pressure passage 27 is connected to a pressure fluid source together with 
said pressure supply chamber 3. A seal member 40 is provided on a piston 
25 to seal between opposite sides of a piston 25. 
When the directional control valve just described is in the state shown in 
FIG. 1, the valve seat 33b of the pilot valve 31 is closed by the valve 
member 34b of the movable valve 35 urged by the spring 36, with the valve 
chamber 33 opening into the atmosphere through the through hole 32a. 
Therefore, each valve body 6 is returned to the original position by the 
urging force of the spring 14, with the pressure supply chamber 3 and 
power output chamber 4b being brought into communication with each other 
while pressure fluid flows outside from the power output port 16b through 
the power output chamber 4b (see FIG. 3). 
If the exciting coil 37 of a pilot valve 31 is energized in the condition 
shown in FIG. 1, the movable valve 35 is attracted to the stator core 38 
against the urging force of the spring 36, with the valve member 34b 
closing the valve seat 33a and the valve member 34b opening the valve seat 
33b. This causes pilot pressure fluid to flow from the pilot pressure 
passage 27 in the intermediate plate 21 into the valve chamber 33 through 
the through hole 32b, and then further into the pilot chamber 30 of the 
cylinder 22 through the connecting hole 26. 
Consequently, the pilot fluid pressure in the pilot chamber 30 drives the 
piston 25, thereby moving the valve body 6 against the urging force of the 
spring 14. Thus, the pressure fluid from the pressure supply chamber 3 is 
switched to the power output chamber 4d, thence flowing outside through 
the power output port 16a (see FIG. 3). 
When the exciting coil 37 is de-energized, the movable valve is returned to 
the original position by the urging force of the spring 36, whereupon the 
valve member 34b closes the valve seat 33b to cut off the inflow of the 
pilot pressure fluid while the valve member 34a opens the valve seat 33b 
to open the valve chamber 33 into the atmosphere. When the inflow of the 
pilot pressure fluid into the pilot chamber 30 is thus cut off, the valve 
body 6 returns to the condition shown in FIG. 1 by the urging force of the 
spring 14, whereupon the pressuire fluid from the pressure supply chamber 
3 is switched to the power output port 4b. 
In the directional control valve just described, the individual valve 
bodies 6 can of course be operated separately by individually energizing 
the exciting coil 37 of each pilot valve 31. 
FIG. 4 shows a second embodiment of this invention, in which a valve casing 
41 has two valve bores 42, each of which accommodates a valve body 43, and 
two pilot valves 31. But no pilot pressure passage like the one 27 in the 
previously described first embodiment is provided in an intermediate plate 
44. The pilot fluid pressure to the pilot valves 31 is individually 
supplied through openings 45 in the intermediate plate 44. 
In FIG. 4, the parts which are the same as or corresponding to those shown 
in FIG. 1 are designated by the same reference characters. 
FIG. 5 shows an example of a directional control valve of this invention in 
service. Two directional control valves, which are the first and second 
preferred embodiments of this invention, are mounted on a base 51. The 
valve bodies 1 and 4, in each of which a plurality of valves are 
juxtaposed, are fixed to the manifold base 51 by means of the mounting 
holes 18. 
The manifold base 51 has a number of power output ports 52a and 52b for the 
individual power output ports of each valve mechanism. Meanwhile, a power 
supply port 53 is common to all valve mechanisms, and pressure exhaust 
ports 54a and 54b are respectively common to the pressure exhaust ports 
17a and 17b of each valve mechanism (see FIG. 3). Instead of using the 
manifold base 51, pressure fluid may also be supplied and discharged 
directly through the individual ports. 
The pilot valve 31 may also be actuated by mechanical force or fluid 
pressure, instead of electromagnetic force. 
Although the two embodiments described above have five ports, a directional 
control valve of this invention may have three or four ports as long as 
each of a plurality of juxtaposed valve mechanisms has individually 
separated power output ports.