Grinder and automatic open/close control device thereof

A grinder including a hollow base, a receptacle, an automatic open/close control device, a grinding unit, and a housing. The automatic open/close control device has a follower member, a bottom cover, a position-limitation structure, and a torsion spring connected between the follower member and the bottom cover. When a friction force produced during grinding of the grinder is greater than a torsional force of a torsion spring, the follower member is rotated relative to the bottom cover from a first position where radial blocks of the follower member block outlets of the bottom cover to a second position where the radial blocks of the follower member are moved away from the outlets of the bottom cover and guide slots of the follower member are moved into alignment with the outlets respectively for discharge of ground powder out of the grinder through the guide slots and the outlets.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to grinders and more particularly, to such a grinder, which automatically opens/closes the ground powder discharging outlets subject to the operation status.

2. Description of the Related Art

There are two different types of spice grinders available on the market, i.e., the manual type and the electric type. When grains or pieces of spice are put into a grinder, it is manually or electrically operated to grind the grains or pieces into powder for direct sprinkling onto food or soup. These grinders are quite popular among users for the advantage of instant grinding. Taiwan Patent No. 415215 (equivalent to U.S. Pat. No. 5,865,384), issued to the present inventor, discloses a similar design. According to this design, the grinder comprises a housing, a transmission shaft, a grinding unit, a particle size adjusting device, and a driving device. This design is functional, however it still has drawbacks. Before putting the material to be ground into the housing, the user must remove the driving device from the housing. This operation manner is inconvenient. Therefore, an improvement is necessary.

The aforesaid prior grinder can perform the basic functions of powder grinding job. However, the ground powder may stay at the clearance of the grinding unit, support frame of the adjustment device or the discharge outlet. When put the grinder on a table or sink at this time, residual ground powder may fall from the grinder to contaminate the surface of the table or sink upon accidental vibration of the grinder, and a further cleaning will be necessary. The present inventor invented an improved design entitled “Shut device for a discharge outlet in a grinder” under Taiwan Patent No. 592113 (equivalent to U.S. Pat. No. 6,880,773). The shut device comprises a stationary part disposed at the bottom of the grinder, and a rotary part. Once the rotary part is turned, hollow openings of the rotary part can align with the discharge outlet for ground powder falling down or stop plates of the rotary part close the discharge outlet for preventing the powder from falling down. Further, the stationary part and the rotary part are conveniently detachable for cleaning, eliminating the non-detachable drawback of the axial connection cap of the prior art design.

The aforesaid shut device is functional in closing/opening the discharge outlet of the grinder. However, the user may forget to adjust the shut device to the open position before using the grinder. In this case, ground powder may be accumulated in the gap between the discharge outlet and the shut device. Therefore, an improvement is still necessary.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a grinder, which automatically opens the ground powder discharging outlets when the friction force produced during the grinding operation of the grinder surpasses the torsional force of a torsion spring thereof, and automatically closes the ground powder discharging outlets by means of energy releasing action of the torsion spring when the grinding operation is stopped.

To achieve this and other objects of the present invention, the grinder comprises a transmission shaft; a hollow base, the hollow base having a grinding chamber in which the transmission shaft suspends, and a plurality of open spaces in a bottom side thereof in communication with the grinding chamber; a grinding unit, the grinding unit comprising a grinding wheel and a grinding base, the grinding wheel being connected to the transmission shaft for rotation with the transmission shaft in the grinding chamber and kept spaced from the grinding base by a gap; a receptacle mounted on a top side of the hollow base, the receptacle comprising a bottom chamber, which holds the grinding base of the grinding unit in place; a housing, which houses the hollow base and a lower part of the receptacle; an automatic open/close control device for closing/opening the open spaces of the hollow base, the automatic open/close control device comprising a follower member connected to a bottom side of the hollow base opposite to the receptacle, the follower member comprising an axle holder fastened to one end of the transmission shaft and a plurality of radial blocks and guide slots radially and alternatively disposed at a bottom side thereof, a bottom cover, the bottom cover comprising a plurality of outlets cut through top and bottom sides thereof corresponding to the guide slots of the follower member, a position-limitation structure provided between the follower member and the bottom cover to secure the bottom cover to the follower member and to limit relative rotary motion between the follower member and the bottom cover within a predetermined angle, and a torsion spring connected between the follower member and the bottom cover; wherein when rotating the housing relative to the receptacle, the bottom cover, the follower member, the transmission shaft and the grinding wheel are rotated with the housing; when the friction force produced between the grinding wheel and the grinding base is greater than the torsional force of the torsion spring, the follower member is rotated relative to the bottom cover from a first position where the radial blocks of the follower member block the outlets of the bottom cover to a second position where the radial blocks of the follower member are moved away from the outlets of the bottom cover and the guide slots of the follower member are moved into alignment with the outlets respectively for discharge of ground powder out of the grinder through the guide slots and the outlets, and at the same time the torsion spring is twisted to preserve energy.

The invention also provides an automatic open/close control device for use in a grinder to automatically open/close the output side of the grinder. The automatic open/close control device comprises a follower member connected to a bottom side of a grinder, the follower member comprising an axle holder fastened to one end of a transmission shaft of the grinder, and a plurality of radial blocks and guide slots radially and alternatively disposed at a bottom side thereof; a bottom cover, the bottom cover comprising a plurality of outlets cut through top and bottom sides thereof corresponding to the guide slots of the follower member; a position-limitation structure provided between the follower member and the bottom cover to secure the bottom cover to the follower member and to limit rotary motion of the follower member relative to the bottom cover within a predetermined angle; and a torsion spring connected between the follower member and the bottom cover. When the friction force produced bin the grinding unit during operation of the grinder is greater than the torsional force of the torsion spring, the follower member is rotated relative to the bottom cover from a first position where the radial blocks of the follower member block the outlets of the bottom cover to a second position where the radial blocks of the follower member are moved away from the outlets of the bottom cover and the guide slots of the follower member are moved into alignment with the outlets respectively for discharge of ground powder out of the grinder through the guide slots and the outlets, and at the same time the torsion spring is twisted to preserve energy.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring toFIGS. 1˜4, a grinder in accordance with the present invention is shown comprised of a transmission shaft1, a base2, a grinding unit3, a receptacle4, a housing5, and an automatic open/close control device6.

The transmission shaft1is a rod member coupled to a grinding wheel31of the grinding unit3for synchronous movement. According to the present preferred embodiment, as shown inFIG. 1, the grinder is a manual grinder, and the transmission shaft1is vertically fastened to an axle holder611of a follower member61of the automatic open/close control device6. Alternatively, a power drive can be used for rotating the transmission shaft1and the grinding wheel31.

The base2is a top-open barrel, having its bottom side fastened to the follower member61of the automatic open/close control device6and its top side connected with the receptacle4. The base2has a grinding chamber21into which the transmission shaft1is inserted from the bottom side, an annular coupling flange22suspending in the bottom open side of the grinding chamber21at the center and coupled to the axle holder611of a follower member61of the automatic open/close control device6, a plurality of radial ribs23radially connected between the annular coupling flange22and the peripheral wall of the grinding chamber21, a plurality of bottom open spaces24disposed around the annular coupling flange22and separated from one another by the radial ribs23for guiding the ground powder out of the grinding chamber21into the automatic open/close control device6, inner threads25extending around the inside wall of the grinding chamber21, a retaining means, for example, ratchet26extending around the top open side of the grinding chamber21, and an engagement means27, for example, gear ring extending around the bottom side of the outer surface of the periphery wall of the grinding chamber21for engagement with a stopping means52on the middle of the inside wall of the housing5to prohibit rotation of the base2with the receptacle4.

The grinding unit3is comprised of the aforesaid grinding wheel31and a grinding base32. The grinding base32is provided at the top side of the grinding wheel31. The grinding wheel31is a conical member having a center mounting hole311coupled to the transmission shaft1. After insertion of the transmission shaft1through the center mounting hole311of the grinding wheel31, a screw cap34is threaded onto the threaded top end11of the transmission shaft1to secure the grinding wheel31to the transmission shaft1. Further, a compression spring33is sleeved onto the transmission shaft1and supported between the screw cap34and the top side of the grinding wheel31. Further, the grinding wheel31has a plurality of spiral wings312equiangularly spaced around the center mounting hole311, a plurality of spiral grooves313equiangularly spaced around the center mounting hole311and separated from one another by the spiral wings312for guiding the loaded material, for example, spice outwardly downwards, a plurality of sloping teeth314arranged around the periphery for moving the loaded material relative to the grinding base32, and a bottom coupling portion315, for example, crossed coupling hole disposed at the center of the bottom side thereof for the coupling of a top coupling portion (crossed coupling block)351of a link35. The link35further has a plurality of bottom mounting rods352respectively fastened to respective vertical mounting grooves612on the axle holder611of the automatic open/close control device6for allowing synchronous rotation of the grinding wheel31with the follower member61and the transmission shaft1.

The grinding base32is a circular, stepped, hollow member fixedly fastened to a bottom rotary cap44of the receptacle4, having a bottom portion321of relatively greater outer diameter and a top body portion322of relatively smaller outer diameter. The top body portion322has a plurality of locating ribs323spaced around the periphery and fastened to the rotary cap44of the receptacle4for synchronous rotation with the rotary cap44, a plurality of oblique guide ribs324spaced around the upper part of its inside wall, and a plurality of fine grinding teeth325spaced around the lower part of its inside wall. The inner diameter of the top body portion322of the grinding base32is slightly smaller than the outer diameter of the grinding wheel31so that the grinding wheel31is prohibited from entering the grinding base32and a gap is constantly kept between the grinding wheel31and the grinding base32. When rotating the grinding wheel31, the loaded grain or strip-like material falls to the spiral grooves313among the spiral wings312and is carried by the spiral wings312and the spiral grooves313toward gaps in between the sloping teeth314and the grinding teeth325for grinding into powder different particle sizes. Fine particle size powder immediately falls out of the grinding unit3. Powder having a particle size greater than the gap between of the grinding wheel31and the grinding base32is continuously ground. According to the present preferred embodiment, the grinding wheel31and the grinding base32are respectively made of acid-proof, wearing proof, anti-oxidation precision ceramics, preventing deterioration of the grinding grain or strip-like material.

The receptacle4is hollow, inverted cone mounted on the base2at the top. Preferably, the receptacle4is transparent so that the user can visually check the amount of the loaded material to be ground. A tubular coupling flange41extending around the bottom side of the receptacle4, and the tubular coupling flange41comprises a opening411, and an annular step412protruded from the inside wall of the tubular coupling flange41. An elastic member42, for example, spring is supported on the annular step412inside the receptacle4. A guide feeder43is supported on the elastic member42inside the receptacle4. The guide feeder43has a center guide hole431for guiding the loaded material into the aforesaid rotary cap44and then the grinding unit3for grinding, and a bottom neck432for the fastening of the rotary cap44. The rotary cap44has a bottom chamber441, which receives the grinding base32, and a plurality of locating grooves442respectively forced into engagement with the locating ribs323of the grinding base32, and a stopping ring36mounted on a bottom side of the bottom chamber441to secure the grinding base32to the bottom side of the rotary cap44.

The rotary cap44further has a tubular top coupling flange443inserted into the tubular coupling flange41extending around the bottom side of the receptacle4, a plurality of longitudinal rails444spaced around the outside wall of the tubular top coupling flange443and respectively coupled to respective longitudinal grooves413on the inside wall of the tubular coupling flange41to guide axial movement of the receptacle4relative to the rotary cap44and to prohibit rotation of the receptacle4relative to the rotary cap44.

The bottom neck432of the guide feeder43is a threaded neck threaded into the internally threaded tubular top coupling flange443of the rotary cap44. Therefore, the guide feeder43and the rotary cap44are fastened together, and the elastic member42is stopped between the guide feeder43and the annular step412of the receptacle4. The rotary cap44further has outer threads445engaged with the inner threads25of the base2. The engagement status between the outer threads445of the rotary cap44and the inner threads25of the base2defines the gap between the grinding wheel31and the grinding base32.

The tubular coupling flange41of the receptacle4has a retaining means414, for example, toothed ring for engagement with the ratchet26of the base2to prohibit rotation of the receptacle4relative to the base2and adjustment of the gap between the grinding base32and the grinding wheel31. Further, a top cover45is covered on the top side of the receptacle4.

The housing5houses the base2and the lower part of the receptacle4. During the use of the grinder, hold the receptacle4with one hand and rotate the housing5relative to the receptacle4with the other hand. When rotating the housing5relative to the receptacle4, the transmission shaft1and the grinding wheel31are rotated with the housing5. The housing5has a connection means51, for example, inner threads extending around the inside wall thereof near the bottom for connection to a bottom cover62of the aforesaid automatic open/close control device6, the aforesaid stopping means52for engagement with the engagement means27of the base2to prohibit rotation of the base2with the receptacle4.

The automatic open/close control device6is comprised of the aforesaid follower member61, the bottom cover62, and a torsion spring63. The follower member61has the aforesaid axle holder611disposed at the center, which receives the bottom end of the transmission shaft1, the aforesaid vertical mounting grooves612formed on the axle holder611and respectively engagement with the bottom mounting rods352of the link35, a plurality of radial blocks613radially extended from and equiangularly spaced around the periphery of the axle holder611near the bottom, a plurality of sector-like guide slots614respectively defined between each two adjacent radial blocks613, limit grooves615extending along the bottom side of the periphery thereof, and a bottom spring hole616at the center of the bottom wall for accommodating one end of the torsion spring63.

The bottom cover62has a coupling means621, for example, outer threads445extending around the outside wall thereof and fastened to the connection means51of the housing5for allowing synchronous rotation of the bottom cover62with the housing5, a plurality of stop rods622upwardly extending from the top wall and equiangularly spaced around the border and coupled to the limit grooves615of the follower member61, hook portions623respectively extending from the stop rods622and hooked on a sliding groove (not shown) at the follower member61above the limit grooves615to prohibit disconnection of the bottom cover62from the follower member61, a plurality of sector-like outlets624cut through the top and bottom sides corresponding to the sector-like guide slots614of the follower member61, a split stub tube625upwardly extending from the top side at the center, and an accommodation hole626defined within the split stub tube625for receiving the other end of the torsion spring63.

Referring toFIG. 5, when adjusting the particle size of the ground powder, lift the receptacle4relative to the housing5. Because the rotary cap44is threaded into the base2and the guide feeder43is fastened to the rotary cap44, the compression spring33is compressed and the engagement means27of the base2is forced into engagement with the stopping means52of the housing5when the receptacle4is lifted relative to the housing5. At this time, the annular step412of the receptacle4is forced against the elastic member42, and the retaining means414of the receptacle4is disengaged from the ratchet26of the base2for allowing rotation of the receptacle4. When the user rotates the rotary cap44relative to the base2, the outer threads445of the rotary cap44are moved along the inner threads25of the base2to change the relative distance between the grinding wheel31and the grinding base32. Thereafter, release the receptacle4from the hand. When the receptacle4is released from the hand, the elastic member42and the compression spring33immediately return to their former shapes to force the retaining means414of the receptacle4into engagement with the ratchet26of the base2again and simultaneously to force the engagement means27of the base2away from the stopping means52of the housing5, finishing the adjustment. According to the present invention, the grinding base32of the grinding unit3is a movable member fastened to the rotary cap44and movable with the rotary cap44relative to the grinding wheel31to adjust the gap between the grinding wheel31and the grinding base32. After adjustment, the particle size of the ground powder is maintained at the desired level.

Referring toFIG. 6, when using the grinder, hold the receptacle4with one hand and rotate the housing5with the other hand. When rotating the housing5, the bottom cover62is forced to rotate the follower member61, the transmission shaft1and the link35, causing rotation of the grinding wheel31relative to the grinding base32. When the grinding pressure produced at the loaded material, for example, pepper between the grinding wheel31and the grinding base32is greater than the torsional force of the torsion spring63, the follower member61is rotated with the bottom cover62, causing the torsion spring63to preserve energy. When the stop rods622are respectively stopped at one end of each of the limit grooves615, the sector-like guide slots614are respectively aimed at the sector like outlets624, and therefore the ground powder is discharged out of the grinder through the sector-like guide slots614and the sector like outlets624.

Referring toFIG. 7, when the rotation of the housing5is stopped, the torsion spring63releases the preserved energy to reverse the, moving the stop rods622along the respective limit grooves615to the other end of each of the limit grooves615. At this time, the radial blocks613of the follower member61are moved to the outlets624to block the outlets624, and therefore the grinder is closed. When all the loaded material (for example, pepper) has been well ground into powder and there is no material left in between the grinding wheel31and the grinding base32, the friction force between the grinding wheel31and the grinding base32becomes smaller than the torsional force of the torsion spring63. At this time, the follower member61runs idle, and the radial blocks613of the follower member61keep blocking the outlets624to block the outlets624.

As stated above, the invention eliminates the drawback of the prior art design in which the opening/closing of the output port is manually controlled by means of a manual control switch. According to the present invention, when the friction pressure between the grinding wheel and the grinding base is greater than the torsion spring, the automatic open/close control device automatically opens the outlets for discharge of the ground powder and simultaneously drives the torsion spring to preserve energy. When the operation is stopped, the torsion spring releases the preserved energy to reverse the automatic open/close control device, thereby closing the outlets.

Further, the grinding unit is set in between the base and the receptacle. After lifting of the receptacle to disengage the retaining means of the receptacle from the retaining means of the base, the receptacle is rotatable relative to the housing to change the gap between the grinding wheel and the grinding base, thereby adjusting the ground powder particle size.