US1931956A - Concrete mixer - Google Patents

Description

E. FREYSSINET CONCRETE MIXER Oct. 24, .1933.

Filed April 3, 1951 2 Sheets-Sheet 1 Oct. 24, 1933. E. FREYSSINET 1,931,956

CONCRETE MIXER Filed April 3, 1931 2 Sheets-Sheet 2 Patented Oct. 24, 1933 UNITED STATES PATENT OFFICE Application April 3, 1931, Serial No. 527,573, and in France May 28, 1930 9 Claims.

It is known that removing gases from concretes and mortars improves their quality. The first attempts for creating a vacuum in a concrete mixer after filling thereof have met with 6 great difiiculties due to the cement dust that is 'drawn into the organs of the air pump. That difilculty has been obviated by submitting the product to the action of a vacuum after its wetting and partial or total mixing, which leads to allow the emulsion of air to be formed and then to destroy it.

My invention has for its object an apparatus which makes it possible to directly manufacture concretes that are wholly free from air, and that without it being necessary to use any vacuum pump in the ordinary meaning of that word.

My apparatus essentially comprises a rigid receiver provided with a door that is made fluidtight by the external pressure so as to prevent the ingress of air, said receiver being divided into two compartments by a flexible and extensible partition, made, for instance of india-rubber.

The outer compartment is adapted to receive gravel, sand, cement and water which are mixed therein, while the inner compartment is adapted to contain water which is forced thereinto or removed therefrom by means of a pump so as to vary the volume of the outer compartment.

The whole forms a vacuum pump having a very high efiiciency in which the door plays the part of a check valve, and the flexible partition actuated by water acts as a piston. The whole apparatus can be so moved as to thoroughly mix the materials introduced into the outer compartment.

A preferred embodiment of my device, given merely by way of example, will be hereinafter described with reference to the appended drawings, in which:

Fig. 1 is a diagrammatic vertical sectional view of my apparatus;

Fig. 2 is a horizontal section on the line 22 of Fig. 1;

Figs. 3 and 4 relate to different embodiments;

Receiver A, which has rigid walls, made preferably of sheet iron, has the shape of a body of revolution about axis X.X, and is adapted to rotate about journals T, T1. Receiver A is provided with a door P acting as a check valve so as to prevent the ingress of air from the atmosphere. A rubber partition S is disposed inside said receiver so as to form an inner compartment C1 between itself and the wall of receiver A, and an outer compartment C. Said partition is fixed by its edge being tightly held between the bolted parts A1 A1 which form receiver A, said partition forming a gasket between said parts. One of the journals T is hollow, which makes it possible to introduce water into compartment C1 by means of a pump P and a coupling 1 connected to tank R located above it so as to prevent inflow of air and to permit rotation of A independently of P1. Pump P1 is adapted to convey a liquid, water for instance, from tank R into space C1, or, on the contrary, from space C1 into tank R, owing to the provision of a system of valves R1 and R2 disposed respectively on the suction and delivery pipes of the pump.

At its upper part, receiver A is provided with a plurality of bars Q adapted to improve the mixing.

The operation of my apparatus is as follows:

Receiver A being so disposed that door P is at the top, said door is opened and cavity C is filled with gravel, sand, cement and water, in the same manner as an ordinary concrete-mixer. The materials have a total volume equal to V and contain in their insterstices a volume of air equal to V1.

Door P is then closed and water is forced into cavity C1 so as to make the volume of cavity C equal to V. Cavity C is then whollyfilled with the materials to be mixed. The air, excepting that which is contained in the interstices, escapes through the door.

Water contained between A1 and S is then drawn out until the volume of C1 is substantially equal to zero. As door P forms a check valve which prevents the ingress of external air, the air present in the interstices of the materials expands in the space located above the concrete, at a pressure equal to:

P being the atmospheric pressure,

V1 the total volume oi. the interstices in the materials,

V2 the decrease of volume of cavity C1.

Now, it is easy to operate in such manner that V2 may be very great with respect to V1. A high vacuum is thus obtained. The concrete-mixer is then rotated about its axis. The mixing is thus effected from the start in a partial vacuum that is sufiicient for practical purposes in most cases. If, after some revolutions, the rotation of A is stopped in such manner that the door be dis posed at the top, and if water is introduced into C1 until the pressure in C is equal to atmospheric pressure, it will be found out that, due to the mixing, the volume of the materials has become V: V and that the air originally present in the interstices is separated from the concrete being formed By further admitting water into 0;, the volume of C is so reduced that water located above the concrete may ooze through the joint of the door. In that manner, the whole of the air is exhausted, excepting some bubbles that may be present in the concrete, and, eventually, the water in excess is also forced out. Said bubbles are very few, owing to the fact that the mixing has taken place in a high vacuum.

By again emptying space C1 and rotating concrete mixer A, the mixing is completed in a vacuum approximately absolute vacuum. It would be possible to still increase the degree of vacuum by a third, a fourth operation, and so on, the amount of air remaining in the concrete decreasing, for each operation, according to geometrical progression.

When the mixing of the concrete and the removed of the gases have been completed, the door is opened in its upper position and the receiver is tilted upside down. It is possible to facilitate the removal of the concrete by means of a hydraulic device operated by the pump and which alternately rases and lets fall one of the journals, T, or by means of any other device producing shocks or vibrations.

My apparatus, as compared with ordinary con-' crete mixers, has not only the advantage of ensuring removal of the gases from the concrete, but the following accessory advantages:

Cleaning is very easy, the rubber pocket being easily turned out and its flexibility facilitating the removal of the cement that might have set during the operation.

Wear and tear is very greatly reduced, owing to the great resistance of india rubber.

It is possible to force out together with air through door P a part of the tempering water that remains over the concrete, and therefore to exactly adjust the volume of water by eliminating the excess. This allows to place at the start the cement in presence of an excess of water so as to reduce the interstices in which air may remain, prior to the beginning of the operation, and makes mixing easier.

Finally, according to my invention, the concrete mixer is easier to build and to drive owing to the fact that mixing is effected by a single rotary motion about journals of normal diameter and disposed in the best possible position for avoiding projections of cement, the same rotary motion also ensuring the bringing into position for filling the concrete mixer, and also for discharging it, as opposed to the ordinary concrete mixers which comprise multiple movements or circular supports mounted on rollers, which are useless with my apparatus.

It should be Well understood that the shape of the elements of my invention may be difierent from what is disclosed in the above described embodiment, any other flexible material may be substituted for india rubber, and rotation about an axis may be replaced by any other method of agitating the mixer, without departing from the principle of my invention. In particular, the door may be provided with an automatic opening device, and it may be arranged in a different manner. The bottom of receiver A may be provided with a drain cock R3 for removing any traces of air in compartment C1.

In the above described embodiment, fluidtightness of the door is ensured through mechanical means, for instance by means of a hand wheel provided with a screw and supported by a cross piece adapted to be secured in position on the mixer. Such device obviously makes it necessary to perform a certain number of operations during the removal of the gases from the mixture, in order to destroy fluid-tightness and thus allow gases and air to escape, or, on the contrary, to reestablish said fluid-tightness during the mix ing operation.

One might also imagine a system of door working automatically in the same manner as a valve, that is to say capable of being hermetically applied on its seat as soon as the external pressure is higher than the pressure inside the concrete mixer, and of parting from said seat in the contrary case. Such a door may for instance be made as shown in Fig. 3, where it consists of a metallic disk, provided at its periphery with a rubber ring I.

In order that the action of the rubber may be 7 effective, it is necessary that the seat U1 of the door on the concrete mixer should be maintained very clean, and that result may be obtained by Washing said seat with a certain quantity of water, for instance with water introduced into the concrete mixer for forming the concrete.

An advantageous arrangement consists in feeding said water through the second journal of the concrete-mixer into a pipe T2 integral with said mixer and connected to an annular conduit Ta provided around the surface of the seat. Water flows onto said seat through holes T4 or a circular slot provided in said annular conduit.

The door may also consist of a mere disk of rubber V1 reinforced by a metallic ring V2, as shown in Fig. 4. Said disk is applied in -a fluidtight manner against the edge of the aperture in the concrete mixer, under the action of the vacuum produced in said mixer, or, on the contrary it is moved away from it so as to allow air and gases to escape when the pressure in the concrete mixer is higher than atmospheric pressure. In this case also the seat of the door will be washed by water flowing from an annular conduit.

Accessorily, deformation of the disk forming the door under the action of the vacuum in the concrete mixer may be used for actuating, through a system of rods, a locking mechanism adapted to prevent rotation of the concrete mixer when, for some reason, the vacuum is not suflicient inside the concrete mixer, owing to defective fluidtightness of the door for instance.

By way of example, in the embodiment shown in Fig. 4, rod V; is operatively connected with a lever 6 pivoted at 7 and which serves to make and brake circuit 8. Said circuit is either the feed circuit of the motor that drives the mixer when said motor is an electric one, or the ignition circuit of the engine that drives said mixer when said engine is of the internal combustion type. It will readily be understood that the parts can be so adjusted that circuit 8 will be closed only when there is a certain predetermined vacuum in the upper chamber of the mixer.

Said locking mechanism will also be adapted to stop the movement of the concrete mixer if during the rotation of the latter, the vacuum that must exist therein is destroyed for some reason.

In the general manner, while I have disclosed what I deem to be the preferred form of my device, I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and, form of the parts without departing from the the volume of the first mentioned chamber, and

spirit of my invention as comprehended within the scope of the appended claims.

What I claim is:

1. A concrete mixer of the type described comprising in combination a receiver having the shape of a body of revolution about a certain axis, said receiver consisting of two elementssecured together along a circle at right angles to said axis, a rubber partition tightly held between the edges of said elements, a circular aperture at right angles to said axis provided in one of said elements, whereby the materials for making the concrete can be poured through said aperture into the mixer, a door for closing said aperture bearing upon the outer 'edge thereof, means for strongly applying said door against said edge of the aperture in a fiuidtight manner, two journals secured to opposite sides of the other element, one of said journals being hollow, whereby water can be forced into the compartment comprised between the rubber partition and the wall of the last mentioned element of the receiver or removed from to said axis provided in one of said elements,

whereby the materials for making the concrete can be poured through said aperture into the mixer, a door for closing said aperture bearing upon the outer edge thereof, means for strongly applying said door against said edge of the aperture in a fluid-tight manner, two'journals fixed on the opposite sides of'the other element, one of said journals being hollow, a tank, a water pump, a pipe connecting said pipe to said hollow journal, whereby water can be forced into the compartment comprised between the rubber partition and the wall of the last mentioned element of the receiver or removed from said space, so as to modify the volume of the other compartment of the receiver, and means for rotating said receiver about said journals.

v 3. A concrete mixer of the type described comprising in combination, a receiver having rigid walls, a flexible partition in said receiver so as to divide it into two chambers, one of which is adapted to receive the materials for making the concrete, means for forcing a liquid into the other chamber and withdrawing it therefrom, means,

provided in the part of the wall of said container that limits the first mentioned chamber, for permitting the outfiow of gases from said chamber and preventing the ingress of external air thereinto, means for agitating said mixer, and means for sealing the first mentioned chamber when the mixer is to be agitated.

4. A concrete mixer of the type described comprising in combination, a receiver having rigid walls, a flexible partition in said receiver so as to divide it into two chambers, an aperture in the part of the wall of said container that limits one of said chambers, whereby the materials for making the concrete can be poured through said aperture into said chamber, a door bearing upon the outer edge of said aperture, means for strongly applying said door against said edge of the aperture for sealing said chamber into fluid-tight manner, means for forcing water into the other chamber and. removing it therefrom, so as to vary means for rotating said mixer about a horizontal axis.

5. A concrete mixer of the type described comprising in combination, a receiver having rigid walls, a rubber partition fixed to the walls of said receiver, so as to divide it into two chambers of variable volume, a circular aperture in the wall of said receiver on one side of said partition, whereby the materials for making the concrete can be poured into the chamber located on that side of said partition, means, adapted to cooperate with said aperture, for allowing the outfiow of gases from said chamber and preventing the ingress of air thereinto through said aperture, and for tightly sealing the last mentioned chamber when the gases have been driven out therefrom, two journals on opposite sides of said receiver, means for forcing .water through one of said journals into said receiver on the other side of said rubber partition into the other chamber and for removing it therefrom, so as to vary the volumes of the two chambers respectively, and means for revolving said receiver on said journals.

6. A concrete mixer of the type described comprising in combination, a receiver having rigid walls, a rubber partition fixed to the walls of said receiver, so as to divide it into two chambers of variable volume, a circular aperture in the wall of said receiver on one side of said partition, whereby the materials for making the concrete can be poured into the chamber located on that side of said partition, a rubber lined circular door bearing upon the outer edge of said aperture and adapted to act as a check valve for allowingthe outflow of gases from said chamber and preventing the ingress of air thereinto through said aperture and for tightly sealing the last mentioned chamber when the gases have been driven out therefrom, two journals secured on opposite sides of said receiver respectively, means for forcing water through one of said journals into said receiver, on the other side of said rubber partition, into the other chamber, and for removing it therefrom, so that the volume of the first mentioned chamber, which contains the materials for making the concrete, can be alternately reduced, for driving out the gases present therein, and increased for causing the gases present in the interstices of said materials to expand into said chamber, and means for revolving said receiver on said journals.

'7. A concrete mixer of the type described according to claim 13 further comprising a circular pipe provided with an annular slot surrounding the outer edge of said aperture, which forms the seat for said door, and means for forcing water into said pipe.

8.A concrete mixer of the type described comprising in combination, a receiver having rigid walls, a rubber partition fixed to the walls of said receiver, so as to divide it into two chambers of variable volume, a circular aperture in the wall of said receiver on one side of said partition, whereby the materials for making the concrete can be poured into the chamber located on that side of said partition, a circular door con sisting of a rubber disk, a metallic ring for reinforcing said disk, said disk bearing upon the outer edge of said aperture and being adapted to act as a check valve for allowing the outflow of gases from said chamber and preventing the ingress of air thereinto through said aperture, and for tightly sealing the last mentioned chamincreased, for causing the gases present in the interstices of said materials to expand into said chamber, and means for revolving said receiver on said journals.

9. A concrete mixer according to claim 5, further comprising means for preventing the rotation thereof on said journals as long as the pressure in the first mentioned chamber is above a certain value.

SSINET.

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