The present invention relates to a device for injecting food products,
for instance pieces of meat, with a liquid, comprising:
- a holder for the pieces of meat for injecting;
- a needle carrier placed in the vicinity of the holder and movable in the direction
towards the holder;
- injection needles fixed to the needle carrier and extending towards the holder;
- feed means for supplying the liquid for injecting to each of the injection
- at least one drive mechanism for driving the needle carrier in its moving direction.
Such devices are generally known.
The drive mechanism of such known devices is generally formed by
a crankshaft mechanism, from which it follows that the movement of the needle carrier
in vertical direction is virtually a sinuoid movement.
Such a drive device is of course quite simple, but the sinuoid movement
resulting therefrom has the drawback that the distribution of the liquid for injecting
in the meat is not uniform in the vertical direction as a consequence of the sinuoid
The object of the present invention is to provide such a device which
can be manufactured at a low cost price, wherein during the downward movement of
the needles in which the injection takes place the speed of the injection needles
is kept as constant as possible.
This objective is achieved in that the drive mechanism comprises
a planetary gear wheel system.
A planetary gear wheel system is understood to comprise a group of
gear wheel mutually engaging at least partially, and the centre of at least one
gear wheels being movable relative to the other gear wheels. One of the gear wheels
could be composed of an internally toothed ring.
As a result of the fact that the drive mechanism comprises such a
planetary gear wheel system, so many degrees of freedom are created for determining
the movement that it is possible to cause the downward stroke of the needles to
be performed at the most uniform possible speed.
Such an injection device is otherwise known from EP-A-0191712, wherein
a practically constant movement is likewise obtained in downward direction, but
which comprises a drive system provided with a cam and a cam disc.
This known device has the drawback however that the cam disc is not
particularly suitable for absorbing great forces, so that in this known device
the operational speed is limited. This known device is moreover subject to a considerable
degree of wear.
In the device according to the present invention this is not the
The present invention will subsequently be elucidated with reference
to the annexed drawings, in which:
- fig. 1 shows a perspective partly broken away view of an injecting device according
to the invention;
- fig. 2 shows a side view of a single drive device according to the invention;
- fig. 3 is a sectional view of the drive device depicted in fig. 2;
- fig. 4 shows a graph representing the movement of the needle carrier in vertical
direction as a function of the angle of rotation of the drive shaft; and
- fig. 5 is a schematic perspective view of a second embodiment of the invention.
The injecting device 1 shown in fig. 1 is formed by a base plate
2 on which are arranged two side plates 3, only one of which is shown. At a distance
from the base plate 2 both side plates 3 are joined by a support plate 4. Arranged
above the support plate 4 is a conveyor belt 5 with which the pieces of meat 6
for injecting are supplied.
It is of course possible to have the return path of the conveyor
belt run through below the plate 5. It is possible to use other conveying mechanisms
instead of the conveyor belt 5, but it is also possible to place the pieces of
meat by hand.
Arranged on the support plate 4 are two side pieces 7, on each of
which is fixed a rod 8. The side pieces 7 serve to guide the conveyor belt, while
the rods 8, which are mutually connected at their top by a connecting strip 9 and
which are also connected to the side plates 3, serve to guide the guide blocks
10. These latter are movable in vertical direction.
Both guide blocks 10 are connected by a needle carrier 11. A large
number of needles 12 ordered in a matrix are attached to the needle carrier 11.
A similarly large number of feed hoses 13 is arranged for supplying
injection liquid to the needles. The hoses 13 are fed by a pump, not shown in the
drawing, for supplying injection liquid. This injection liquid will generally be
formed by brine.
Arranged below the needle carrier 11 is a beam-like closing means
35 which normally closes the feed of injection liquid to the needles and only allows
the injection liquid to pass to the needles when in contact with the meat for injecting.
Thus is achieved that the needles only inject into the meat.
In order to move the needle carrier in vertical direction a drive
device is arranged on the base plate 2 but under the support plate 3, which device
is formed by an electric motor 14 which is fixed onto a gearbox 15. The gearbox
15 rests on the base plate 2 by means of a console 16.
The drive device will be discussed more precisely hereinafter, also
with reference to fig. 2 and 3.
Fixed against both sides of the gearbox 15 is a hollow shaft 17 which
is closed at its end by a flange 18. Fastened against the flange 18 by means of
a bolt connection 19 is a sleeve 20 which is provided on one side with a toothing
21. This toothing 21 forms the sun-wheel. Further arranged in sleeve 20 is a bearing
22 in which is mounted the drive shaft 23 extending concentrically of the hollow
A disc 24 is fastened onto the drive shaft, which extends beyond
the sleeve 20. Mounted in the disc 24 by means of a bearing 25 is a sleeve 26,
to which is fixed a gear wheel 27. The latter is in engagement with the toothing
21 and also forms a planet gear wheel of the planetary gear wheel system.
Fixed onto the sleeve 26 concentrically relative to the shaft is
the shaft end part 28. A connecting rod 30 is fixed onto this shaft end part by
means of a bearing 29. Mounted in the other end of the connecting rod 30 by means
of a bearing 31 is a shaft end part 32 which is fixedly connected to a driving
rod 33. The driving rod 33 is fixedly connected to the guide block 10. A guide
34 is arranged on the side piece 7 to guide the connecting rod 30. The connecting
rod 30 can thus move only in vertical direction.
The operation of the above described device will be described hereinbelow.
When both drive shafts 23 are driven by means of the electric motor
14, the drive shaft 23 of each drive device will cause the disc 24 to rotate. As
a result the gear wheel 27 will be carried along in rotation and, due to engagement
in the stationary toothing 21, will also rotate about its own axis. The sleeve
26 thus performs a compound, cycloid movement.
The shaft end part 28 which is preferably, although not necessarily,
placed concentrically on the sleeve will thus also execute a cycloid movement.
This compound movement is transmitted to the connecting rod 30, and therewith to
the driving rod 33, so that both guide blocks 10 are thus driven in vertical direction.
Because this construction has a large number of selectable variables,
it becomes possible to make the guide blocks 10, and therefore the needles 12,
execute a vertical movement such that during the downward stroke the movement is
practically constant. It is then also possible to perform the return stroke as
rapidly as possible to thus cause time loss and loss of injection liquid to be
as small as possible.
It will be apparent that such a mechanism comprises a large number
of degrees of freedom; it is for instance possible to alter the ratios between
the numbers of teeth on both gear wheels, it is possible to vary the angular position
of the shaft end part 28 on the sleeve 26 and it is possible to arrange the one
gear wheel in shifted position.
Each change results in a different movement, thus resulting in a
large number of degrees of freedom. In the graph of fig. 4 is shown an example
of such a movement.
It can be seen from the graph that during the downward movement the
speed is practically constant, while during the upward movement the speed is as
great as possible.
It can also be seen from the graph that the injection needles extend
into the meat only during part of the stroke. The possibility therefore exists
of varying the thickness of the pieces of meat for injecting; the thickness may
in any case not be so great that the needles are not released in their highest
point. It is also important that the needles do reach the lower edge of the meat
and in the lowest position possibly extend through the meat, although the time
duration within which this occurs must be as small as possible to be able to execute
the injection process in a time as short as possible and to prevent loss of injection
liquid in some situations, when for instance no separate value has been provided.
In order to provide space for the needles the support is therefore perforated.
Finally, fig. 5 shows an alternative embodiment of the invention.
In this embodiment there is only one transversely placed drive device, the connecting
rod 30 of which is coupled to a yoke 36 which is formed by a plate 37 onto which
the connecting rod 30 engages. The yoke further comprises two rods 38 which are
connected to the needle carrier 11. The rods 38 are both guided through holes arranged
in the side pieces 7. It is of course also possible to apply other types of guiding,
for instance by rollers.
It will be apparent that diverse changes can be made to the construction
without deviating from the invention.