FR2528996A1 - Liq. level detector with tilting float - contains moving steel ball causing tilting action for operation of microswitches signalling position - Google Patents

Abstract

A float comprises rigid foam reinforced by a coating of polyester resin. This foam is moulded around a detector capsule comprising a cylinder with covers at each end. The detector cylinder contains a steel ball and two microswitches which are activated by the ball during its course of travel. A sealed electrical cable from the remote end of the cylinder connects to the microswitches and is also used to suspend the complete assembly. During use, the float takes up position where the detector is uppermost or horizontal or facing downwards. The two microswitches signal these three states which correspond to low, normal or high level of liquid.

Description

 The present invention relates to instruments of the "level detector of a tilting float liquid" type, allowing the deceleration, then the stopping of a filling at a chosen level.

 Known devices of this kind use mercury contacts. Mercury, free in a glass bulb, establishes by wetting electrodes, various contacts depending on the inclination of the bulb.

 Such devices exhibit phenomena of "twists" during changes of state, when the surface of the liquid to be detected is disturbed. This is the case for filling from above.

 When these "twists" cannot be tolerated by the filling mode technology, each of the information supplied by the detector must be stored, causing the complexity of the automatic control.

 The tilt level detector according to the invention makes it possible to avoid these drawbacks.

 The detector is composed of a portion of cylinder containing a ball. Two mini-switches placed on either side of this cylinder portion delimit the stroke of the ball, so as to allow the two mini-switches to be simultaneously in the rest position.

 The assembly "cylinder, ball, mini-breakers" is placed in another portion of cylinder plugged at its two ends, thus forming the detection capsule. The capsule is vertical, in the waiting position.

 A waterproof electrical cable, connected to the mini-switches, crosses the upper part of the capsule, and will serve as a means of suspension to the device.

 A spherical float, made of rigid foam, with a diameter equal to the length of the capsule, is molded around the lower 2/3 of the latter, causing the tilting condition during immersion.

 The detector thus described will switch from 1800 from its suspension position when the level of the liquid reaches it. If the level continues to rise, the detector will float on the surface of the liquid; capsule down, float up.

The set "ball, mini-breakers", delivers three states which are a function of the inclination of the detector
1st condition: the detector is suspended, the liquid has not reached it. It is the standby position allowing filling at high speed. The weight of the ball creates sufficient bearing force to keep the lower mini-breaker in the working position.

The upper mini-breaker is at rest.

 2nd state: when the liquid reaches the detector, the changeover begins. The downforce generated by the weight of the ball decreases. When approaching the horizontal position, the mini-breaker pushes the ball. The two mini-switches are at rest. This is the low speed fill order.

 3rd state: the detector continues its tilting, and when approaching total inversion, the bearing force of the ball activates the upper mini-breaker, delivering the end of pleating information.

 The stability of these three states, is obtained by the difference which exists between the support force necessary to make break a mini-breaker from the state of rest to the working state, and the force of release necessary, to make l reverse operation.

 On the other hand, the displacement of the center of gravity caused by the stroke of the lip creates a locking phenomenon during a change of state.

 Experience has shown that the stability of the three states is increased, by choosing the weight of the ball so that the support force in the vertical position is approximately 120% of the minimum support force required. to obtain the "work-rest" switching of the mini-breaker.

 This coefficient of 120% may be adjusted according to the density and the extent of the disturbances of the surface of the liquid.

 The accompanying drawing presents a sectional view of the complete device, a profile view of the internal mechanism alone, of the three typical positions of the detector, as well as the corresponding states of the mini-switches.

 As it is represented in F2, the internal mechanism comprises a portion of cylinder (4) enclosing a steel ball (3).

 The mini-switches (1) and (2) limit the stroke of the ball and are positioned so that they can be in the rest position simultaneously.

 The internal mechanism is placed in a cylinder (5) blocked at its two ends by the covers (6) and (7), thus forming the complete detection capsule (8) shown in F1.

 All mechanical parts are made of stainless steel.

 The float made of rigid foam (9) reinforced by a thickness of food grade polyester resin (10), is molded around the detection capsule (8).

 The device, object of the invention, can be used in the food and petrochemical field.

Claims (1)

 Level switch with tilting float characterized in that it is composed of a rigid red float (9), reinforced with a polyester resin film (10), a detection capsule (8) comprising a cylinder portion ( 4), a ball (3) and two microswitches (1) and (2), making it possible to obtain three states (11) (12) and (13) depending on the inclination of the float.