Abstrict In a flow meter, especially for liquid cooling media in injection
molds, comprising a housing with an inlet and outlet conduit and
inside the housing a piston that is slidable against the force of
an axially acting spring by the pressure of the fluid flowing through
the housing in such a way that the displacement of the piston takes
place in dependence upon the flow rate and is indicated through
a window, provision is made, to attain a high measuring accuracy
with a simple construction, for a helical spring (22) that is guided
in extension of the inlet conduit (2) in an axial direction to be
disposed in such a way that the entering fluid is transported around
the centrically disposed helical spring (22).
Claims What is claimed is:
1. A flow meter, especially for liquid cooling media in injection
molds, comprising a housing with an inlet and outlet conduit and
inside the housing a piston that is slidable against the force of
an axially acting spring by the pressure of the fluid flowing through
the housing in such a way that the displacement of the piston takes
place in dependence upon the flow rate and is indicated through
a window, wherein a helical spring (22) that is guided in extension
of the inlet conduit (2) in an axial direction is disposed in such
a way that the entering fluid is transported around the centrically
disposed helical spring (22).
2. A flow meter according to claim 1 wherein the entering fluid,
after passing the piston (24), flows into an expansion chamber (26)
with an enlarged cross section.
3. A flow meter according to claim 2 wherein the expansion chamber
(26) is encompassed at least partly by a window (5 sleeve 11).
4. A flow meter according to claim 1 wherein the outlet conduit
(3) is disposed in an axial extension of the helical spring (22).
5. A flow meter according to claim 4 wherein a counter bearing
or guide element (15) for the helical spring (22) is disposed on
a shoulder (webs 18) of the outlet conduit (3), said shoulder being
provided with radial openings (19) in such a way that the fluid
can enter from the expansion chamber (26) into the outlet conduit
(3).
6. A flow meter according to claim 1 wherein a center housing
part (4) has a thread in such a way that the flow meter can be screwed
directly onto a manifold (31).
7. A flow meter according to claim 1 wherein the outlet conduit
(3) has a flow adjustment valve (28 33) disposed downstream from
it.
8. A flow meter according to claim 7 wherein the adjustment valve
is a ball valve (28).
9. A flow meter according to claim 8 wherein the adjustment valve
is a plug valve (33).
10. A flow meter according to claim 9 wherein the plug valve (33)
has a valve seat (34) and a valve lifter (35) in such a way that
the valve lifter (35) is axially movable relative to the valve seat
(34) via an external knurled nut (38) or the like.
11. A flow meter according to claim 1 wherein the piston has an
assigned electro-optical position reading device.
12. A flow meter according to claim 11 wherein the electro-optical
position reading device is formed by a luminous source or luminous
source field and a photoelectric cell or photoelectric cell field.
Description BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention is directed to a flow meter, especially
for liquid cooling media in injection molds, comprising a housing
with an inlet and outlet conduit and inside the housing a piston
that is slidable against the force of an axially acting spring by
the pressure of the fluid flowing through the housing in such a
way that the displacement of the piston takes place in dependence
upon the flow rate and is indicated through a window.
[0003] 2. Background Art
[0004] A flow meter according to the preamble is known from U.S.
Pat. No. 3979955 wherein the flowing fluid compresses a spring,
which shifts a plate, the deflection of which is readable on a scale.
[0005] U.S. Pat. No. 3805611 also describes a flow meter wherein
a piston is displaced against the force of a spring. Disposed on
the piston is a conical measuring piece, the position of which is
changed proportion ally t o the flow rate.
[0006] From U.S. Pat. Nos. 4389901 and 5343763 flow meters
are known with a hollow conical insert through which the fluid flows.
The housing is transparent and provided with a scale so that the
degree of shifting of a piston against the force of a spring that
is caused by the flowing fluid can be seen or read.
[0007] From U.S. Pat. No. 4945771 a measuring device for determining
the flow rate is known that comprises a compression spring mounted
on a piston and an air flow controlling cone.
[0008] U.S. Pat. No. 4497202 describes a flow meter having radial
slots to permit a laminar flow. These radial slots are formed in
an annular plate.
[0009] Further flow meters are known from U.S. Pat. Nos. 828108
2244552 3218853 3408865 3889535 4524616 5044199
and 5554805.
[0010] In known systems of this type the medium flows through the
interior of the helical screw. A design of this type is expensive
to construct and unsatisfactory regarding its measuring accuracy.
SUMMARY OF THE INVENTION
[0011] With this as the starting point, the invention has as its
object to further develop a flow meter of the above type in such
a way that it can be implemented in the most simple and cost effective
manner possible while providing a high degree of measuring accuracy.
[0012] This object is met according to the invention with a helical
spring that is guided in extension of the inlet conduit in an axial
direction and disposed in such a way that the entering fluid is
transported around the centrally disposed helical spring. This centrical
position of the helical spring serves to attain particularly simple
geometric conditions that permit the use of a minimum of components
with an easy assembly.
[0013] A further design of the invention provides for the entering
fluid to flow into an expansion chamber with an enlarged cross section
after passing the piston. An expansion chamber of this type prevents
turbulence from forming in the outlet area, which could cause the
piston to oscillate with an alternating laminar and turbulent flow
and accordingly impact the accuracy and readability of the indicator.
[0014] For a direct visibility and display of the piston position,
the expansion chamber may be encompassed at least partly by a window,
which may have a scale that is readable from the outside.
[0015] The outlet conduit is advantageously disposed in an axial
extension of the helical spring, and a counter bearing or guide
element for the helical spring may be disposed on a shoulder of
the outlet conduit, said shoulder being provided with radial openings
in such a way that the fluid can enter from the expansion chamber
into the outlet conduit. This provides for an advantageous construction
that ensures a laminar discharge of the fluid.
[0016] Provision is advantageously made for the inlet conduit to
have an exterior thread in such a way that the flow meter can be
screwed directly into a manifold. A manifold of this type is known
from DE 40 32 562 C2. In this manner an extraordinarily compact
unit is attained and it is possible to read the flow rate in multiple
cooling fluid cycles more or less simultaneously.
[0017] A flow adjusting valve, which may be formed by a ball valve
or plug valve, may be disposed downstream from the outlet conduit.
[0018] In the latter embodiment, provision is preferably made for
the ball valve to have a valve seat and a valve lifter in such a
way that the valve lifter is axially moveable via an external knurled
nut or the like.
[0019] Provision is preferably made for the piston position to
be measured by an electro-optical measuring device. It may be formed,
for example, by a row of light-emitting diodes on one side of the
piston and a corresponding row of photoelectric cells on the other
side of the piston so that a certain num5 ber of photoelectric cells
is illuminated or darkened, depending on the displacement of the
piston, and an electronic position measuring signal can be formed
accordingly.
[0020] The invention will be described in further detail below
based on preferred embodiments in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 shows a longitudinal section through a first embodiment,
[0022] FIG. 2 through a further embodiment with a ball valve, and
[0023] FIG. 3 an embodiment that is screwed onto a manifold.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] An inventive flow meter that is shown in the drawing comprises
a housing 1 with an inlet conduit 2 and an outlet conduit 3 which
are each designed as a tube connection.
[0025] A central housing section 4 with a window 5 is screwed by
means of an inside thread 6 onto an exterior thread 7 of a base-like
widening 8 of the inlet conduit 2 with the window 5 designed as
an opening, thus providing free view onto a sleeve element 11 of
transparent plastic that is held in place by seals 9 10.
[0026] The outlet conduit 3 also has a base-like shoulder 12 with
an external thread 13 onto which an inside thread 14 of the housing
center part 4 is screwed. This also creates a counter bearing or
guide element 15 via a sealing ring 16 against the sleeve element
11.
[0027] The counter bearing or guide element 15 has, in extension
of the outlet conduit 3 a through-opening 17 in the extension
of which axial webs 18 are formed, between which through-slots 19
are provided. The webs 18 carry a counter bearing 20 and the extensions
21 of the webs 18 form a guide section for a helical spring 22 that
actuates, via an annular shoulder 23 a piston 24 that is axially
displaceable in the inlet line 2 and conically widens towards the
top and sits in a corresponding conical recess 25 of the base 8.
The recess 25 connects to the expansion chamber 26 which is bounded
by the sleeve element 11.
[0028] If fluid enters through the inlet conduit 2 in the direction
of the arrow 27 the piston 24 is displaced upward in the drawing
against the force of the helical spring 22 and accordingly unblocks
a passage region relative to the recess 25 so that the fluid enters
into the expansion chamber 26 and can expand there. Through the
slots 19 the fluid then enters into the through-opening 17 and into
the outlet conduit 3.
[0029] The degree of deflection of the piston 24 is proportional
to the flow rate, with the deflection of the piston being readable
on the sleeve element 11 via the window 5 based on a scale not shown
in the drawing.
[0030] The embodiment shown in FIG. 2 corresponds, in its basic
construction, to the embodiment according to FIG. 1 except that
the part 12' has a ball-type through-valve 28 through which the
fluid must pass before it enters into the outlet conduit 3.
[0031] In the embodiment shown in FIG. 3 the inside thread 6 of
the center housing part 4 is screwed onto the exterior thread 29
on a neck-like projection 30 of a manifold 3 1 which has a manifold
conduit 32 extending perpendicular to the drawing plane in FIG.
3.
[0032] Furthermore, a plug valve 33 is connected to the center
housing part 4 in the embodiment according to FIG. 3 the valve
seat 34 of which is formed in the part 12". The valve plug
35 with a sealing ring 36 sits in a groove 37 of a knurled nut 38
which, with its inside thread 39 acts together with an external
thread 40 on the part 12" so that the valve cone 35 may be
moved up or down by actuating the knurled nut 38 and the flow rate
becomes adjustable in this manner. |