GB2563820A

GB2563820A - Bean grinder concentric

Info

Publication number: GB2563820A
Application number: GB1707868.4A
Authority: GB
Inventors: John Nicholson Martin
Original assignee: NICHOLSON DESIGN CONSULTANTS Ltd
Current assignee: NICHOLSON DESIGN CONSULTANTS Ltd
Priority date: 2017-05-16
Filing date: 2017-05-16
Publication date: 2019-01-02
Also published as: GB201707868D0

Abstract

A bean grinder comprises an inner grinding burr 3 and a complementary outer grinding burr 4. A shaft 5 carries the inner burr and a bearing 6 journals the shaft for rotation about a rotational axis. An outer burr support 8 defines a recess 7 within which the outer burr is located and the bearing is arranged concentrically with the recess, such that the inner burr on the shaft is located substantially concentrically with respect to the outer burr in the recess. The bean grinder may further comprise a body and a drive mechanism from which the shaft projects. The grinder may further comprise a grinding support plate 9 located in the recess and having the bearing centrally secured in it. The bearing may be a journal bearing and the outer burr may be axially moveable in the outer burr support and rotationally restrained within. In use, the grinder aims to consistently maintain the gap between the grinding surfaces of the burrs.

Description

BEAN GRINDER

The present invention relates to a bean grinder, particularly though not exclusively a coffee bean grinder.

In a coffee grinder, it is desirable to accurately maintain a rotationally driven inner grinding burr in a design position along its axis of rotation and for the actual axis of rotation to remain aligned with respect to a fixed outer grind burr. It is also desirable to allow the position of the outer burr to be accurately and repeatable adjusted along the axis of rotation relative to the inner burr and to remain concentrically aligned with the inner. If this can be achieved, the gap between the two grinding surfaces of the burrs can be consistently maintained around its perimeter during the grinding process and accurately adjustable with the result that consistent ground size particles of a controllable size in produced grounds are accurately produced.

The object of the present invention is to provide an improved bean grinder.

According to the invention I provide a bean grinder comprising: • an inner grinding burr, • a complementary outer grinding burr; • a shaft carrying the inner burr; • a bearing journalling the shaft for location of an axis of rotation of the inner burr and • an outer burr support transversely locating the outer burr, • the support having a recess in which the outer burr is accommodated and • the bearing being located at least substantially concentrically with the recess, the arrangement being such that the inner burr on the shaft and the outer burr in the recess are held at least substantially concentric.

Preferably, the bean grinder has: • a body with which the outer burr support is fast and • a drive mechanism from which the shaft projects, the mechanism being supported in the body remote from the shaft and the outer burr support.

The outer burr support could be a separate part held fast in the body. Alternatively it could be an integral feature of the body or a part thereof, with the recess being machined or not as required by the method of formation of the body or part thereof. In the preferred embodiment, the outer burr support recess is formed in an upper body held fast with a lower body, with the interposition of an intermediate member.

Whilst I can envisage the outer burr support to have an integral transverse portion with the bearing centrally secured in a machined counter-bore, preferably the bean grinder includes a bearing support plate transversely located in the recess and having the bearing centrally secured in it, whereby the shaft is centred in the recess for centring the inner burr in it.

The bearing could be a combined journal and thrust bearing with the support of the mechanism providing orientation for the shaft at the bearing. Alternatively, the bearing could be a journal bearing with the support of the mechanism providing orientation for the shaft at the bearing together with axial reaction to thrust generated in bean grinding.

Preferably: • the drive mechanism comprises an electric motor and an inline reduction gearbox; • the inner burr incorporates or has connected thereto fingers radially extending across the bearing support plate or the integral transverse portion of the outer burr support and the recess in the outer burr support has an aperture through which the fingers can sweep bean grounds from the burrs; • a grounds expulsion member is provided between the inner burr and the bearing support plate or the integral transverse portion of the outer burr support and has a hub from which the fingers radiate in a swept back manner, the hub being on the shaft and fast with the inner burr for rotation therewith; • the outer burr is axially movable of the shaft in the outer burr support and rotationally restrained in therein; • means is provided both for urging the outer burr inwards of the outer burr support to adjust the outer burr axially of the inner burr, the outer burr urging means reacting thrust on the outer burr generated in bean grinding and for returning the outer burr outwards of the outer burr support.

Again, preferably: • the means for urging the outer burr inwards comprises a threaded extension of the outer burr support and a complementary threaded grind adjustment ring arranged to bear on the outer burr to urge it inwards of the outer burr support, directly or via an intermediate member; and • the means for returning the outer burr outwards comprises a member fast with the outer burr and having radial extensions thereof, springs outwards acting outwards against the radial extension and notches in the outer burr support, receiving the radial extension for rotationally restraining the outer bun-providing reaction abutments for the springs, which thereby urge the member having the extension and the outer burr outwards.

To help understanding of the invention, a specific embodiment thereof will now be described by way of example and with reference to the accompanying drawings, in which:

Figure lisa perspective view of a bean grinder;

Figure 2 is a side section view of the bean grinder of figure 1 taken along A-A

Figure 3 is an enlarged side section detail view of the bean grinder of figure 1;

Figure 4 is a rear section view of the bean grinder of figure 1 taken along A-A;

Figure 5 is a perspective exploded view of the bean grinder;

Figure 6 is a horizontal section view of the bean grinder of figure 1;

Figure 7 is a perspective partial section view of the bean grinder of figure 1;

Figure 8 is a detailed view of the base of the bean grinder of figure 1.

Referring to the drawings, a bean grinder 1 with a body 2 has an inner grinding burr 3 and a complementary outer grinding burr 4. The burrs are commercially available from Italmill Grinding Technology S.r.l for instance. The inner burr is carried on a shaft 5 journaled in a bearing 6 locating the axis A of rotation of the inner burr. The outer burr is transversely located in a recess 7 in a support 8. The bearing is carried concentrically with the recess, whereby the inner burr on the shaft and the outer burr in the recess are held at least substantially concentric.

To assure concentricity of the bearing 6 with the recess 7, it is carried in a bearing support plate 9, which is a clearance fit in the recess, thus transversely located in it. The outer race 10 of the bearing is a push fit in a seat 11 in the underside of the plate and captivated between the seat and a bottom 12 of the recess.

Screws 14 pulling the plate against the recess bottom 12 pass through this and engage in an intermediate member 15, itself held fast via screws 16 with a lower body portion 17 of the grinder. An upper body portion 18 has the outer burr support 8 formed in it, whereby the two sets of screws attach the body portions together. To ensure their local concentricity the intermediate member has a flanged rim 19 engaging in both these portions. A drive mechanism 21 is provided for inner burr 3 and the shaft 5 which is the output shaft of a two stage epicyclic gearbox 22 driven by a motor 23 below it. These components are well known and will not be described in detail. The motor has a housing 24 having two lugs 25 extending down from it. Via elastomeric bushes 26, they engage in sockets 27 arranged in a lower end 28 of the lower body portion 17. The lugs react the torque generated between the burrs during grinding. The thrust generated in grinding is reacted as described below. A grounds expulsion member 31 is provided between the inner burr 3 and the bearing support plate 9. It has three swept back radial fingers 32, which move grounds out radially. The fingers radiate from a hub 33, which although recessed to accommodate a boss 34 of the bearing support plate 9, in which the bearing 6 is accommodated, has a central sleeve 35 extending along the shaft 5, to abut the inner race 36 of the bearing. Grinding thrust downwards on the inner burr is reacted via the sleeve 35 and inner race 36 to the outer race 10 and the recess bottom 12. When a screw 37 holding the inner burr to the shaft is tightened, its compression of the sleeve 35 is reacted via the inner race to a circlip 38 mounted on the shaft 5 beneath the inner race 36.

Whilst the outer burr 4 is adjustable in its approach to the inner burr 3, as described below, the outer burr must not rotate. To ensure this, it has an upper attachment 41 fixed to it by screws 42 extending up through it. The attachment has a pair of tabs 43 extending radially which are received in slots 44 cut in the side of the support 8. The slots have blind bores 45, accommodating springs 46. The tabs and slots co-operate to hold the outer burr against rotating and the tabs and springs urge it upwards, i.e. urge the outer burr upwards away from the inner burr. A grind adjustment funnel ring 47 acts down on the upper attachment 41 of the outer burr 4. It has a threaded collar 48 received in a threaded bore 49 of the upper body portion 18 above an outwards of the outer burr support 8. Screwing the funnel ring in urges the outer burr down and unscrewing allows it to rise. The funnel ring carries a setting ring 51. The two rings have co-operating lips 52,53, which hold the setting ring on the funnel ring. Inside, the setting ring has a series of indents 54. The funnel ring has a bore 55 at the level of these indents in which is accommodated a spring 56 and a detent ball 57. The arrangement allows the setting ring to be adjusted on the funnel ring and hold its adjustment. On a radial face at the top of the upper body portion, indicia 58 are moulded. In use, the funnel is wound in to bottom the outer burr, the setting ring is zeroed by aligning a mark 59 on the outside of setting ring with the zero of the indicia. The funnel ring is then backed off by the number of indicia corresponding to the required grinding separation of the burrs. The threading of the collar 48 and the bore 49 is fine, whereby friction in between the funnel ring and the upper bore portion holds the funnel ring in its adjusted position. This in turn allows the funnel ring to resist upwards thrust on the outer burr generated in bean grinding.

The funnel ring 47 has a tapered aperture 60 for funnelling beans 61 to the burrs.

The grounds from the burrs drops into the path of the swept back radial fingers 32 of the grounds expulsion member 31. They pass the grounds to a pair of vertically arranged openings 62 in the wall 63 of the burr support recess 7, at the lowest point of the bearing support plate 9. This slopes at a normal angle of 15° to horizontal, the axis A of rotation of the inner burr 3 and the drive mechanism 21 being at this angle to the vertical. A spout 64 is provided for receiving the grounds. It has an inclination of 10° to the vertical in the opposite direction to that of the axis A. It provides a grounds path P from the grinder. It will be noted that the axis A and the path P form an invert V. The point of the V substantially at the burrs, although the true intersection of the axis A and the centre line of the spout is slightly above the burrs. Whist the spout is slightly more upright than the axis A, the bisector of the V is effectively vertical.

The spout 64 is generally circular in cross-section. At its upper end 65, it is shaped to abut the outer contour 66 of the recess 7, with a top pin 67 engaging in a recess 68 formed in the outer contour. A lug 69 engages the underside of the recess bottom 12 at a cut-out 70 in the intermediate member 15. A screw 71 bearing on the bearing support plate 9 passes through the bottom 12 and engages in the lug to positively locate the spout. It also passes through an aperture 72 in the lower body 17.

The lower body 17 has a base 81 fitted beneath it and projecting forwards to extend beneath the spout. The base 8land the body 2 are in invert 7 configuration.

The base 81 has a two part stand 82 for a grounds collection cup 83. With the cup on the stand, beneath the bottom 84 of the spout, the invert V configuration of the axis A and the grounds path P, taking account of the tall/thin configuration of the drive mechanism 21 and the lower body 17 closely following the drive mechanism below the spout aperture 72, the arrangement allows the cup to collect the grounds 85.

In development of the bean grinder, which will normally be used for grinding coffee, whilst little grounds remained neither in the burrs nor at the bottom of the burr support recess, there was a tendency for grounds to hang up in the spout especially during certain weather conditions. This appears to be an electrostatic effect, due to the manner in which the grounds collect on the spout, particularly at the bottom 84 and spout aperture 72.

Surprisingly it was found that by making the stand 82 of wood, and indeed by providing wooden feet 86, the electrostatic grounds hang up disappeared.

Consistently I have ground say lOgm of beans and collected lOgm of grounds (the exact weights depending on the weight of an integer number of coffee beans). This effect was achieved with a steel grounds cup, a plastics material spout and a metallic body.

The two part stand comprises a cover 87 over most of the hollow base 81, and held in place by a screw 88 having a head 89 left proud, and a circular saucer 90 with a blind central bore formed in its base for location on the screw head 89.

The rear of the hollow base has inside a cable control moulding 91 with an aperture 92 opening outwards for a power cable 93 and a clamp 94 for the cable as it passes up into the lower body portion. The arrangement allows the cable to be inserted into the base for storage and withdrawn for use.

The cable extends in the lower body to a printed circuit board 95 accommodated alongside the gearbox 22. It has a switch 96 for initiating supply of power to the motor. The printed circuit board has an interlock micro-switch 97. The upper body has a lid 98 pivotally mounted at the rear by a hinge 102 for closing over the funnel ring 47. The lid carries a magnet 99 and the upper body a steel insert 100. These hold the lid closed over the funnel for use of the grinder. In this fully closed position, a lid projection 103 feature on the lid 98 depresses a plunger 101 and the micro-switch makes contact to allow the grinder to operate when the switch 96 is activated. When the lid 98 is opened and before a point when access can be gained to the tapered aperture 60, the lid projection feature 103 disengages from the plunger 101 and the micro-switch breaks contact to prevent the grinder to operate when the switch 96 is activated.

The materials of the components of the bean grinder can be chosen as at will. I envisage that the body portions, the base, the grounds expulsion member and the bean funnel will be of light alloy. The spout, the setting ring, the intermediate member and the bearing support plate will be of polymeric material. The lid will be of transparent polymeric material to allow visibility of the tapered aperture, setting ring and grinding burrs. The wooden parts will of course be of wood.

The invention is not intended to be restricted to the details of the above described embodiment. For instance, the setting indicia could be provided on the setting ring with the zeroing mark being provided on the upper body portion or the burrs could be flat burrs rather than conical burrs or the motive power source could be human hand.

Claims

CLAIMS:

1. A bean grinder (1) comprising: • an inner grinding burr (3), • a complementary outer grinding burr (4) ; • a shaft (5) carrying the inner burr; • a bearing (6) journalling the shaft for location of an axis of rotation of the inner burr and • an outer burr support (8) transversely locating the outer burr, • the support having a recess (7) in which the outer burr is accommodated and • the bearing being located at least substantially concentrically with the recess, the arrangement being such that the inner burr on the shaft and the outer burr in the recess are held at least substantially concentric.

2. A bean grinder as claimed in claim 1, including: • a body (2) with which the outer burr support (8) is fast and • a drive mechanism (21) from which the shaft (5) projects, the mechanism being supported in the body remote from the shaft and the outer burr support.

3. A bean grinder as claimed in claim 2, wherein the outer burr support is one of: • a separate part held fast in the body or • an integral feature of the body or • an integral feature of a part of the body of the bean grinder, preferably fastened to another part of the body via an intermediate member (15).

4. A bean grinder as claimed in claim 1, claim 2 or claim 3, including a bearing support plate (9) transversely located in the recess (7) and having the bearing (6) centrally secured in it, whereby the shaft (5) is centred in the recess for centring the inner burr (3) in it.

5. A bean grinder as claimed in claim 4, wherein the intermediate member (15) is provided and the bearing support plate (9) is fastened in the recess (7) with fastenings fastening the part of the body having the outer burr support (8) recess to the intermediate member.

6. A bean grinder as claimed in claim 1, claim 2 or claim 3, wherein the outer burr support (8) has an integral transverse portion and the bearing (6) is centrally secured in the transverse portion, whereby the shaft (5) is centred in the recess (7) for centring the inner burr (3) in it.

7. A bean grinder as claimed in any one of claims 2 to 6, wherein the bearing (6) is a combined journal and thrust bearing and the support of the mechanism provides orientation for the shaft (5) at the bearing.

8. A bean grinder as claimed in any one of claims 2 to 6, wherein the bearing (6) is a journal bearing and the support of the mechanism provides orientation for the shaft (5) at the bearing together with axial reaction to thrust generated in bean grinding.

9. A bean grinder as claimed in any one of claims 2 to 8, wherein the drive mechanism (21) comprises an electric motor (23) and an inline reduction gearbox (22).

10. A bean grinder as claimed in preceding claim, wherein: • the inner burr (3) incorporates or has connected thereto fingers (32) radially extending across the bearing support plate (9) or the integral transverse portion of the outer burr support (8) and • the recess (7) in the outer burr support has one or more apertures (62) through which the fingers can sweep bean grounds (85) from the burrs.

11. A bean grinder as claimed in claim 10, including a grounds expulsion member (31): • provided between the inner burr (3) and the bearing support plate (9) or the integral transverse portion of the outer burr support (8) and having • a hub (33) from which the fingers (32) radiate in a swept back manner, the hub being on the shaft (5) and fast with the inner burr for rotation therewith.

12. A bean grinder as claimed in preceding claim, wherein the outer burr (4) is axially movable of the shaft (5) in the outer burr support (8) and rotationally restrained in therein.

13. A bean grinder as claimed in claim 12, including; • means for urging the outer burr (4) inwards of the outer burr support (8) to adjust the outer burr axially of the inner burr (3), the outer burr urging means reacting thrust on the outer burr generated in bean grinding and • means for returning the outer burr outwards of the outer burr support.

14. A bean grinder as claimed in claim 13, wherein the means for urging the outer burr (4) inwards comprises: • a threaded extension (49) of the outer burr support (8) and • a complementarily threaded grind adjustment ring (47) arranged to bear on the outer burr to urge it inwards of the outer burr support, directly or via an intermediate member.

15. A bean grinder as claimed in claim 13 or claim 14, wherein the means for returning the outer burr (4) outwards comprises: • a member (41) fast with the outer burr and having radial extensions (43) thereof • springs (46) outwards acting outwards against the radial extension and • notches (44) in the outer burr support (8), receiving the radial extension for rotationally restraining the outer burr providing reaction abutments for the springs, which thereby urge the member having the extension and the outer burr outwards.