Device for driving rodents from subterranean burrows

Rodents are driven off and kept away from burrows in a subterranean area by driving cylindrical housing containing respective shock wave generators into the ground. The shock wave generators are each designed to produce at timed intervals, damped vibrations which radiate into the surrounding ground.

FIELD OF THE INVENTION 
My present invention relates to a device for driving rodents and, 
especially, burrowing rodents such as field mice, voles, moles and 
groundhogs, woodchucks and the like, from their subterranean shelters or 
burrows. 
BACKGROUND OF THE INVENTION 
It is well known that certain burrowing rodents, and especially woodchucks, 
groundhogs, mice, voles and moles, are highly sensitive to shock waves, 
especially when these shock waves are transmitted through the ground to 
the animals in their burrows and that, when subjected to such shock waves, 
these animals tend to leave the burrows and hence are driven off from 
regions which are to be protected from them. This high physical 
sensitivity renders them particularly susceptible to the application of 
waves to the ground or soil which tend to surround the animals in their 
burrows, induce fright or fear and generate a flight syndrome. 
It has been proposed heretofore, therefore, to drive off such rodents by 
the use of acoustic waves and hence to free an area subjected to such 
waves from these rodents. For this purpose, devices have been provided to 
apply acoustic waves of an appropriate amplitude or volume and these 
devices generally have transmitters, transducers or like output elements 
emitting the acoustic waves and which are intended to be inserted into the 
holes affording access to the burrows. The use of such devices, however, 
is disadvantageous, at least in part, because it requires the user to find 
the holes opening into the burrows to insert the device, a difficult 
operation. 
OBJECTS OF THE INVENTION 
It is the principal object of the present invention to provide an improved 
device for ridding a particular ground or area of burrowing rodents. 
Another object of this invention is to overcome the disadvantages of 
earlier systems whereby acoustic waves have been utilized to drive 
burrowing rodents from their subterranean nesting sites. 
SUMMARY OF THE INVENTION 
I have now discovered that these objects can be attained with improved 
effect in the removal of rodents from a particular subterranean area 
utilizing a device which is formed with a casing adapted to be driven into 
the ground and provided with means for generating, rather than acoustic 
waves, damped vibrations within the ground which impinge from all 
directions upon the animal and thus are exceptionally effective in 
producing a sensation of terror which is manifested by rapid flight and a 
reluctance of the rodents to return. The damped vibration is imparted to 
the ground at shorter or longer intervals as may be convenient or desired. 
According to the invention, the casing can have a relatively thin-wall body 
which can be driven into the ground to a predetermined depth and a 
vibration generator for the generation of damped vibration in the form of 
shocks, which vibrations are distributed substantially uniformly in all 
directions from the casing to the surrounding ground. 
According to another feature of the invention the housing has the 
configuration of a cylinder at one end of which the generator for damped 
vibrations is provided and which includes an electric current source and, 
also in this cylindrical portion, electronic circuitry connected to this 
source and to the pulse generator for controlling the latter. 
The latter end of the housing may be a rounded or pointed structure which 
can have a thicker wall. 
According to yet another feature of the invention the pulse generator or 
the shock wave generator for producing the damped vibration comprises an 
electromagnet whose armature is in the configuration of a disc and, upon 
energization of an electromagnet coil, against the force of a weak spring 
strikes the stator of the magnet to generate the shock which is 
transmitted to the shell or casing of the housing to reduce the damped 
oscillation, radiating outwardly to the surrounding earth. 
The current source is preferably a chargeable storage battery or 
accumulator and can be included in the casing so as to make the latter 
independent of some external current source and which is connected by 
appropriate conductors to the aforementioned circuitry at the magnets. The 
circuit of course can include a timer to establish the timing of the 
successive shock waves. 
I have found, moreover, that it is advantageous to provide the magnet with 
a spiral spring establishing a spacing between the magnet core and the 
armature and the core can be relatively massive, i.e. an iron body to 
which the armature is attractable and against which the armature impacts. 
The armature can be a plate provided on a central axially moving pin 
centrally connected by a screw arrangement with a mass and guided on a pin 
lodged in the end of the housing. 
The coil arrangement for generating the impulse can be a coil of the type 
used in loudspeakers and which affords a considerable simplification of 
the structure. 
The device of the invention allows cultivation protected against rodent 
infestations over the range area around the device. The effective range of 
the device can be 15 to 30 meters and consequently, corresponding devices 
can be spaced between 30 to 60 meters apart to ensure substantially 
complete freedom from rodent infestation of the cultivated plot.

SPECIFIC DESCRIPTION 
From FIG. 1 it will be apparent that the device of the invention can 
comprise a relatively elongated cylindrical housing 1 provided at an end 2 
which is to be driven into the ground with a relatively thick-wall 
hemispherical tip while the remainder of the housing has a comparatively 
thin wall. The opposite end of the housing is provided at 3 with a 
removable cap. 
The cap 3 is provided on its end and along its apron or parameter with ribs 
3a offset by about 90.degree. from one another about the periphery of the 
cap to enable the cap 3 to be more readily gripped and to facilitate 
threading of the cap onto an externally threaded portion of the housing 1. 
Sealing is effected between the wall of cylinder 1 and the interior of the 
cap by a pair of sealing rings represented at 3b. 
The cap retains a pair of batteries 6 within the housing and these 
batteries can be resiliently supported by springs 3c while having a 
terminal bearing upon the contact plate 5 which can be supported by pins 
from the cap 3. 
At the opposite end, the batteries can be supported by springs 5b. The 
batteries of course are electrically connected to the circuit represented 
in FIG. 4 at the terminals which have been illustrated. 
A contact plate 7 supports the electronic circuit and support bolts 8 are 
provided to mount the contact plate and the printed circuit plate on a 
support 7c. 
The armature or pulse-generating hammer 9 is shown to have the 
configuration of a disc which can be driven electromagnetically against 
the core of an electromagnet core in the compartment 9a and can be pressed 
away from the armature by a spring which has not been illustrated and 
which can be interposed between the armature and the magnet core. At 10 I 
have shown the electronic circuitry provided on the contact and circuit 
plates and representing the circuit shown in FIG. 4. 
In operation of course, once the apparatus is assembled and turned on by 
inserting the batteries and turning on the switch, the assembly can be 
driven into the ground at locations between 30 and 60 meters apart and 
will automatically generate shock waves at preset times or with preset 
intervals in the form of damped vibrations. The damping is effected by the 
fact that only a single impulse is utilized to generate the short wave by 
impact of the armature against the electromagnet which is fixed to the 
casing. 
In the embodiment of FIG. 2, a mass 11a is clamped or screwed onto a 
central pin 12 and is secured in place by a counternut. The pin 12 aligns 
this mass with an armature 13 or iron which can be drawn toward an 
electromagnet whose coil is shown at 15 to compress the spring 16. When 
the magnet is released, the iron mass 13 impacts upon the mass 11a. 
At 17 I have shown a holding plate which is connected by spacer sleeves 18 
and transmission bolts 19 with a fastening plate. A sheet 21 (printed 
circuit band) carries the electronic circuit elements which are received 
in the compartment 22. Terminals 23 are provided to contact the circuitry 
to the batteries in the compartment 24. A mounting plate has been shown at 
25. 
This device functions similarly to that described in FIG. 1, for example, 
the spring 16 can be sufficiently strong that it drives the armature 13 
upon release by the electromagnet that it impacts against the mass 11 or 
can be relatively weak so that the impact is generated primarily by 
engagement of the mass 13 with the electromagnetic core. The mass 11a can 
be composed of lead. The armature can also be provided with or as a 
permanent magnet so poled with respect to the electromagnet that it is 
repelled against the mass 11a and the latter is driven against the 
housing. 
In any of these casings a damped vibration will be established in the 
manner described. 
In FIG. 3 the hemispherical end 2 of the housing receives a permanent 
magnet 28 in the form of a ring which is connected to an isolating body 30 
defining a gap in which the excitation coil 31 is provided. The excitation 
coil 31 activates a membrane 33 which is connected with a lead mass 34 on 
a pin 35. The space 36 receives electronic circuit and the mass 34 can be 
driven by the loudspeaker-like vibration generating system against the 
hemispherical housing 2. 
The circuit shown in FIG. 4 which I prefer to use employs an IC 1 of type 
4011 constituting an oscillator with six terminals with the oscillation 
output being applied to a binary counter. The output of the IC 2 of type 
4020 supplies oscillations of a large period. The IC 1, only the 
significant terminals of which have been shown to be connected, applies 
brief pulses to the transistor BC 547 which in turn controls the 
transistor 2N 3055 with the latter being rendered conductive to generate 
the coil energization for each shock. A switch not shown can be utilized 
to control the rate of succession of the pulses between rapid and slow, 
and a monitoring switch can be provided to trigger the circuit as a test. 
The condenser C 7 serves as the energy store which is discharged through 
the coil VI and elements R 3, C 1 and D 1, namely, a resistor, condenser 
and choke serve to protect the energy storage condenser and to improve the 
function. 
Diode D 2 protects the transistor 2N 3055 from any adverse effect of the 
induction voltage of the coil. The condenser C-6 and resistor R 4 have a 
pulse-rounding function and tend to round off the rectangular pulse 
thereof to the control resistor BC 547. Naturally any conventional timing 
circuit can equally be used for the self-energization of the device.