Improvements in or relating to mixer devices

Abstract

 A mixer device suitable for mixing or disintegrating materials which, when subjected to mixing or disintegration, give off noxious gases or infectious bacteria. The device includes a mixer head comprising a rotor element and a stator element which is supported below a lid for an open-topped mixing vessel. A rotor shaft extends upwardly from the head and through an aperture in the lid. A seal is provided between the rotor shaft and the lid and the lid is adapted for sealing engagement with the vessel. A drive motor is mounted on a support with an output shaft thereof extending downwardly towards the rotor shaft. Means are provided for releasably coupling the motor shaft to the rotor shaft and cooperating locating means are provided on the lid and on the motor support. The motor support is movable along a vertical guide and operating means are provided for moving the support downwardly along the guide until the motor shaft is coupled to the rotor shaft and the locating means on the support engage the locating means on the lid.

Description

[0001] This invention relates to mixer devices suitable for use with materials which, when subject to mixing or disintegration, give off noxious gases or infectious bacteria.

[0002] In medical laboratories it is often necessary to prepare a mixture of materials which include infected animal tissue or to disintegrate an infected organ or human excreta. It is then essential that mixing or disintegrating be carried out under conditions which prevent the escape of noxious gases and bacteria into the surrounding atmosphere.

[0003] Devices currently available for mixing such materials include a mixer head comprising rotor and stator elements which is supported below a lid for a mixing vessel. A rotor shaft extends upwardly from the head via an aperture in the lid and seals are provided between the shaft and the lid and between the lid and the vessel. To use the device an operator must lift the vessel and the lid to bring locating means on the lid into engagement with locating means on the housing of a motor, thereby to secure the vessel to the housing, and to couple the rotor shaft to a downwardly extending motor shaft. The seal between the rotor shaft is operative to prevent the escape of gases or bacteria both before and after the rotor shaft has been coupled to the motor shaft.

[0004] When using such devices an operator needs to use one hand to lift the vessel and the other hand to operate the locating means. This is impractical with large vessels and there is therefore a need for a device which can be operated without lifting the vessel and lid to present these components to a motor.

[0005] It is desirable also that the mixing or disintegration be performed in a mixing vessel made of plastics or the like resilient material which is relatively cheap and can be disposed of after use.

[0006] According to the invention there is provided a mixer device suitable for mixing or disintegrating materials which, when subjected to mixing or disintegration, give off noxious gases or infectious bacteria, the device comprising a mixing head comprising a rotor element mounted on a rotor shaft and a cooperating stator element, means supporting the stator element below a lid for an open-topped mixing vessel, the rotor shaft extending upwardly from the mixing head and through an aperture in the lid, sealing means being provided between the rotor shaft and the lid, and the lid being adapted at or near the periphery thereof for sealing engagement with a side wall of the vessel, a drive motor, a support for the drive motor, a guide along which the motor support is movable in a direction having a vertical component, means for releasably coupling an output shaft of the motor to the rotor shaft, and operating means for moving the motor support along the guide, whereby, in use, the device is arranged with the lid resting on the side wall of the vessel, the mixing head within the vessel, and the motor and rotor shafts axially aligned or substantially axially aligned, and the operating means are then actuated to cause the motor support to move downwardly along the guide until the coupling means operate to couple the motor shaft to the rotor shaft so that mixing may be effected, and, after mixing, the operating means can be further actuated to cause the motor support to move upwardly along the guide so that the motor shaft is decoupled from the rotor shaft.

[0007] The invention will now be described, by way of example, with reference to the accompanying drawings, in which:-

Fig. 1 is a vertical section of a mixer device according to the invention;

Fig. 2 is a scrap-sectional view of an operating means in the device of Figure 1; and

Fig. 3 is a scrap-sectional view of part of a second mixer device according to the invention.

[0008] The device shown in Figures 1 and 2 of the drawings is suitable for use in a medical laboratory where materials such as human tissues, organs or excreta have to be mixed or disintegrated. Such materials are usually stored in a refrigerated condition and may give off noxious gases or bacteria when brought up to room temperature and subjected to mixing or disintegration. Mixing is conveniently effected in a cylindrical, open-topped mixing vessel of plastics or the like flexible material.

[0009] Referring to Figure 1 of the drawings, a suitable vessel 1 for use with the present device has a circular base 3 and a generally cylindrical side wall 5. A short distance below the rim of the vessel 1 is a flange 7 having a radially outer section which is downturned. The flange 7 is used in securing the vessel 1 to the mixer device, as hereinafter described.

[0010] The present mixer device includes a lid 9 for closing the vessel 1 and carries a support 11 for a mixer head 13. Means 15 are provided for locating the lid 9 and the head 13 relative to a housing 17 for a drive motor (not shown).

[0011] To ensure a fluid-tight seal between the periphery of the lid 9 and the side wall 5 of the vessel 1, a lower part 19 of the lid is tapered, an external flange 21 is formed on an upper part of the lid, and an 0-ring 23 of elastomeric material is fitted into a circumferential groove of part-circular section between the part 19 and the flange 21. When the device is assembled, as shown in Figure 1, the tapered part 19 of the lid 9 is fitted into the top of the vessel 1 and the 0-ring 23 engages an upper edge of the side wall 5. A clamping ring 20 has an upturned, radially inner section which is fitted beneath the flange 7 on the vessel 1. The lid 9 is clamped to the vessel 1 by means of a series of bolts 24, each of which extends upwardly through aligned apertures in the clamping ring 20 and the lid 9 and has a nut 22 threadably engaged with its upper end. By tightening the nuts 22 the lid 9 is drawn downwardly so that the 0- ring 23 is compressed and forms a fluid-tight seal between the lid and the vessel 1.

[0012] The mixer head 13 includes a rotor element 23 and a cooperating stator element 25. The rotor element 23 is formed of a plurality of blades outstanding from a circular rotor plate and is secured to a lower end of a rotor shaft 31. The stator element 25 is formed of an apertured cylindrical side wall having a flange at its upper end.

[0013] The flange on the stator element 25 is screwed to the undersurface of an annular stator plate 37, which forms part of the above- mentioned support 11. Four pillars 39 support the stator plate 37 below an annular plate 41 at an upper end of the support 11.

[0014] Secured to the stator element 25 are a pair of upstanding baffle plates 27. The plates 27 are disposed at diametrically opposed locations on the element 25. Each is formed of a lower section 33 which is vertical and an upper section 35 which is inclined to the vertical at an angle between 10 and 45⁰, preferably 30⁰. Alternatively, both upper and lower sections are vertical.

[0015] The locating means 15 include a hollow cylindrical member 43 which has its bottom wall 45 fitted into a central aperture in the lid 9 and an apertured boss on the wall 45 fitted into the central aperture in the plate 41. A locating pin 47 is provided near to an upper end of the member 43 and the member has a bevelled upper edge.

[0016] As shown in Figure 1, the rotor element 23 is disposed inside the stator element 25. Shaft 31 extends upwardly from the rotor element, first via a bush 51, which is fitted into a central aperture in the stator plate 37 and serves as a bearing for the shaft, and then via the apertured boss on the wall 45 to the interior of the member 43. An upper end of the shaft 31 is tapered, and just below the taper is a drive pin 53.

[0017] A seal 55 for preventing the escape of noxious gases or bacteria from the interior of the vessel 1 is provided within the cylindrical member 43 of the locating means 15. The seal 55 is a seal of the kind disclosed in British specification No. 1,084,803. As disclosed in that specification the seal 55 includes a stationary seal seat, which is fitted into the central aperture in the bottom wall 45 of the member 43, and a seal member, which is rotatable with the shaft 31 and which is urged downwardly into engagement with the stationary seal seat by a helical spring. An 0-ring is provided between the rotatable member and the shaft 31. An upper end of the spring 61 engages a seal drive collar 63 on the shaft 31.

[0018] An inlet pipe 64 and an outlet pipe 66 communicate with the interior of the vessel 1 via respective inlet and outlet apertures in the lid 9. The pipes 64 and 66, which are used for flushing the interior of the vessel 1 after mixing, are normally closed by rubber bungs.

[0019] A support 67 for the drive motor includes the housing 17 and a vertical column 65 which has the housing 17 mounted on an upper end thereof. The column 65 is slidable within a tubular member 69 whose lower end is fitted into an aperture in a top wall of a housing 71. Movement of the column 65 relative to the member 69 is confined to movement in a vertical direction by a screw 74 which is threadably engaged in the top wall of the housing 71 and has one end thereof projecting into a vertical groove 76 in the column. Sleeve bearings 73, spaced apart by a bush spacer 75, are provided within the tubular member 69. A cylindrical shroud 77 extends downwardly from the housing 17, coaxially of and outside the member 69.

[0020] Within the housing 71 are operating means which include a cam 79 mounted on a horizontal spindle 81. As shown in Figure 2, the spindle 81 is supported by a bearing 83 in a rear wall of the housing 71 and a bearing 85 in a front wall of the housing. A forward end of the spindle 81 extends through an aperture in the front wall of the housing and has a handle 87 secured thereto.

[0021] The column 65 normally rests with its lower end on the cam 79 in the housing 71.

[0022] An output shaft 89 of the motor extends vertically downwardly from the housing 17. Secured to a lower end of the shaft 89 is a sleeve 91 for coupling the shaft to the rotor shaft 31. To this end the sleeve 91 is formed with two slots 93 for receiving respective opposite ends of the pin 53 on the shaft 31. Each slot 93 has one axially extending edge and one edge which is inclined to the axis of the sleeve 91.

[0023] A hollow cylindrical member 95 is secured to the housing 17, coaxially of the shaft 89, and serves as a locating means which cooperates with the locating means 15 on the lid 9. To this end a lower section of the member 95 is formed with an increased internal diameter so that a shoulder 99 is formed between this lower section and an upper section of the member. Additionally, a bevel is formed at a lower edge of the lower section of the member 95 and an axially extending slot 105 is provided for receiving the pin 47 on the locating means 15.

[0024] The housing 71 is secured to a horizontally extending framework 107 and a plate 109 for supporting the vessel 1 has studs 111 which are fitted into apertures 113 in the framework. The apertures 113 are disposed at a predetermined distance from the housing 71 so that the rotor shaft 31 is approximately coaxial with the shaft 89 of the motor when the vessel is located centrally of the plate 109.

[0025] Prior to using the present device the handle 87 has been rotated to bring the housing 17 to a raised, inoperative position and the lid 9 is placed on top of the vessel 1 with the mixer head 13 inside the vessel. An operator can then place the vessel 1 together with the lid 9 on the plate 109 with the member 43 of the locating means 15 axially aligned, or nearly axially aligned, with the member 95. The lid 9 is clamped on to the vessel 1 in the manner described above. Since the shaft 31 is disengaged from the sleeve 91, the spring which is engaged between the seal member in the seal 55 and the drive collar 63, urges the shaft 31 upwardly to a position wherein the plate in the rotor 23 engages the stator plate 37.

[0026] By rotating the handle 87, the operator allows the column 65, which rests on the,cam 79, to move downwardly within the member 69. In the course of this downwards movement the bevelled edge on the lower section of the member 95 engages the bevelled edge on the member 43. During subsequent downwards movement engagement of the bevels causes lid 9 and vessel 1 to be moved slightly in a radial direction so that the rotor shaft 31 becomes axially aligned with the output shaft 89 of the motor. The pin 47 on the member 43 enters the slot 105 and the pin 53 on the rotor shaft 31 enters the slots 93 in the sleeve 91 and rides up the inclined edge of each slot.

[0027] Once the output shaft 89 of the motor has engaged the rotor shaft 31, further downwards movement of the sleeve 91 forces the rotor shaft 31 downwardly so that the rotor plate is disengaged from the stator plate 37. The spring in the seal 55 is further compressed during this downwards movement and maintains the seal member firmly engaged with the seal seat, thus providing a gas-tight seal between the shaft 31 and the wall 45, and hence between the shaft and the support 11 and the lid 9.

[0028] The downwards movement of the column 65, the motor and the motor support 67 continues until the shoulder 99 on the member 95 has engaged the upper edge of the member 43. The dimensions of the present device and of the vessel 1 are such that upon further rotation of the handle 87 the cam 79 is rotated to an angular position in which it has disengaged from the lower end of the column 65. The motor and the motor support 67 are then supported by the lid 9 and the vessel 1, apart from frictional forces acting between the column 65 and the bearings 73 and spacer 75.

[0029] The motor in the housing 17 is now switched on so that the rotor element 23 is rotated. As the blades of the element 23 rotate, material within the stator element 25 is expelled radially outwardly via the apertures in the side wall and fresh material is drawn upwardly into the stator element. The material is subjected to large shearing forces, which effect thorough mixing or disintegration, as the material passes first between the rotating blades 27 and the wall 25 and then through the apertures in the wall.

[0030] In the absence of the baffle plates 27, material expelled from the stator element has a high velocity in the circumferential direction as well as in a radially outwards direction. This circumferential movement may be sufficient to produce a vortex of sufficient magnitude for the mixer head 13 to be completely emptied of material. The baffle plates 27 reduce this circumferential flow sufficiently to prevent such a vortex action.

[0031] At the end of mixing or disintegration, the handle 87 is rotated so that the cam 79 reengages the lower end of the column 65 and then moves the column upwardly so that the locating means 15 and 95 are disengaged. The spring in the seal 55 expands slightly and forces the rotor shaft upwardly until the rotor plate engages the stator plate 37. However, the spring is still sufficiently compressed to maintain the seal member in engagement with the seal seat, thereby maintaining a gas-tight seal between the rotor shaft 31 and the support 11 and the lid 9.

[0032] The vessel 1 and lid 9 can then be removed from the housing 17 and framework 107 and placed in a fume cupboard, prior to releasing the bolts 24 and removing the lid from the vessel.

[0033] Alternatively, the vessel 1 and the lid 9 are removed from the housing 17 and the framework 107 and placed in a fume cupboard. The rubber bung is removed from the pipe 64 and a sample of the mixed material is withdrawn from the vessel 1 by means of a pipette. After replacing the bung the vessel and the lid are carried to a sluice, both bungs are removed, and the liquid is removed from the vessel by pouring through the outlet pipe 64. The interior of the vessel 1 is then cleansed, by connecting a source of water to the inlet pipe 64 and thereby forcing any liquid or solid material remaining inside the vessel 1 or on the undersurface of the lid 9 outwardly via the outlet pipe 66.

[0034] Referring to Figure 3 of the drawings, a second device according to the invention is a modification of the device shown in Figures 1 and 2 and is designed for use with mixing vessels which are made of plastics or the like flexible material but which are more accurately manufactured, in particular with vessels whose internal diameter at the top thereof is equal or substantially equal to a predetermined value. In the device of Figure 3 a lower part 19 of a lid 9 is tapered and there is a flange 21 above the part 19. There is, however, no part-circular groove between the part 19 and the flange 21 and no 0-ring corresponding to the 0-ring 23 of Figure 1. Instead, a circular groove 26 is formed on the upper surface of the lid 9.

[0035] In using the device of Figure 3, the lid 9 is arranged with the lower tapered part 19 extending into the top of a vessel 1, the diameter of the part being such that the lid rests with the top edge of the vessel engaging the part 19 at a location between the top and bottom of the part and with the flange 21 vertically spaced above the top edge. The operating means are then actuated, as described above, so that the member 95 moves down to engage the member 43, the motor shaft 89 engages the rotor shaft 31, and the rotor plate is disengaged from the stator plate 37. Downwards movement continues until the shoulder 99 on the member 95 has engaged the top of the member 43 and the cam 79 has been disengaged from the column 65.

[0036] The combined weight of the housing 17 and the motor within the housing, the column 65, the locating means 15 and member 95, the lid 9 and the mixer head 13 forces the tapered part 19 of the lid into the top of the vessel 1, and this downwards movement of the part 19 causes a radially outwards movement of the flexible material of the vessel 1. The upper edge of the vessel 1 is therefore maintained in a fully stretched or slightly expanded condition and a fluid tight seal is formed between the vessel 1 and the lid 9.

[0037] A plurality of spring clips (not shown) are then employed to maintain the lid 9 in engagement with the vessel 1, each clip having one limb engaged below the flange 7 on the vessel and another limb engaged in the circular groove 22 on the lid.

[0038] The device described above may have a microswitch connected in series with the drive motor. The microswitch is arranged to be open when the output shaft 89 of the motor is decoupled from the rotor shaft 31 and closed when the two shafts are coupled together. This prevents rotation of the rotor shaft 31 whilst the plate in the rotor 23 is engaged with the stator plate 37. It also prevents damage to the pin 53 and the sleeve 91 due to engagement of the rotating shaft 89 with the stationary rotor shaft 31. The microswitch can be arranged to be operated by a further cam on the spindle 81.

Claims

1. A mixer device suitable for mixing or disintegrating materials which, when subjected to mixing or disintegration, give off noxious gases or infectious bacteria, the device comprising a mixing head comprising a rotor element mounted on a rotor shaft and a cooperating stator element, means supporting the stator element below a lid for an open-topped mixing vessel, the rotor shaft extending upwardly from the mixing head and through an aperture in the lid, sealing means being provided between the rotor shaft and the lid, and the lid being adapted at or near the periphery thereof for sealing engagement with a side wall of the vessel, a drive motor, a support for the drive motor, a guide along which the motor support is movable in a direction having a vertical component, means for releasably coupling an output shaft of the motor to the rotor shaft, and operating means for moving the motor support along the guide, whereby, in use, the device is arranged with the lid resting on the side wall of the vessel, the mixing head within the vessel, and the motor and rotor shafts axially aligned or substantially axially aligned, and the operating means are then actuated to cause the motor support to move downwardly along the guide until the coupling means operate to couple the motor shaft to the rotor shaft so that mixing may be effected, and,.after mixing, the operating means can be further actuated to cause the motor support to move upwardly along the guide so that the motor shaft is decoupled from the rotor shaft.

2. A mixer device as claimed in claim 1, wherein the lid is provided with locating means for engagement with locating means on the motor support when the motor and rotor shafts are coupled together, and the operating means provide support for the motor support during initial downwards movement thereof but are disengaged from the motor support after the motor and rotor shafts are coupled together and the locating means on the lid and the motor support are engaged, the lid and the vessel then supporting or assisting in supporting the motor support.

3. A mixer device as claimed in claim 2, wherein the guide is upstanding from a base and the device is designed for use with a mixing vessel having a side wall of predetermined height standing on the base, the device being such that the operating means are disengaged from the motor support after the support has moved to a predetermined vertical location above the base and the lid and the vessel are supporting or assisting in supporting the motor support.

4. A mixer device as claimed in claim 2 or 3, wherein the motor support includes an upstanding column which is movable along the guide, and the operating means include a cam mounted on a shaft, actuation of the operating means causing rotation of the shaft so that the cam moves from an angular position wherein a lower end of the column rests on the cam to an angular position wherein the cam is disengaged from the column.

5. A mixer device as claimed in claim 2, 3 or 4, wherein a lower part of the lid is tapered in a downwards direction, whereby when the operating means are disengaged from the motor support a downwards force is applied to the lid, the tapered part of the lid is forced into the upper end of the vessel, and a further force is applied to the vessel in a radially outwards direction, the radially outwards force causing a slight deformation of the side wall of the vessel and serving to maintain the lid and the vessel in sealing engagement.

6. A mixer device as claimed in claim 1, 2, 3 or 4, wherein a sealing element is fitted to the lid, and means are provided for clamping together the lid and the vessel with the sealing element serving to provide the said sealing engagement.

7. A mixer device as claimed in any one of the preceding claims, wherein at least one upstanding baffle plate extends outwardly from the stator element, the or each baffle plate serving to reduce circumferential flow of liquid expelled from the stator element.

8. A mixer device as claimed in claim 7, wherein the or each baffle plate comprises a vertical lower section and an upper section inclined to the vertical.

9. A mixer device as claimed in any one of the preceding claims, wherein a microswitch is connected to the drive motor and is arranged to be operated to allow electric current to be supplied to the motor only when the motor shaft has been coupled to the rotor shaft.

Drawing