A transmitter is mounted on a cultivator hitched to a tractor or the like for emitting a noninvasive sensor beam generally parallel to and in front of a soil-cultivating implement which tills the soil. Mechanism detects echoes from obstructions in the path of the implement and controls mechanism for retracting the implement so that the implement does not engage the obstructions. When an obstruction has passed, the implement is returned to its working position extending transversely to the direction of movement of the cultivator.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a cultivator having mechanism for sensing 
an obstruction in the path of the soil-cultivating implement of the 
cultivator and mechanism for automatically retracting such implement so as 
not to engage the obstruction. 
2. Prior Art 
In a known cultivator, a soil-cultivating implement projects transversely 
of the direction of movement of such implement through the soil and a 
mechanical probe is positioned in front of the leading edge of the 
implement. When the probe engages against an obstruction, such as the 
agricultural crop being tended, rearward swinging movement of the 
implement is instituted. In such a known cultivator, however, the rearward 
movement of the soil-cultivating implement can be too slow so that the 
crop is damaged. In addition, the mechanical probe itself can damage the 
crop. 
SUMMARY OF THE INVENTION 
The principal object of the present invention is to provide a novel 
crop-sensing cultivator of the type having a soil-cultivating implement 
and mechanism for moving the implement out of the path of an obstruction, 
such as the agricultural crop being tended. 
In the preferred embodiment of the present invention, the foregoing object 
is accomplished by providing such a cultivator with a transmitter for 
emitting a noninvasive sensor beam toward a predetermined location in 
front of the cultivating implement, mechanism for detecting echoes from 
obstructions in the path of the implement, and mechanism controlled by the 
detecting mechanism for retracting the implement so that the implement 
does not engage the obstruction. 
Preferably, the sensor beam is radiated approximately parallel to and in 
front of the leading edge of the soil-cultivating implement, and the 
height and angle of the beam relative to the implement can be adjusted to 
adapt the cultivator for tending different types of crops. 
The echo-detecting mechanism can be coupled to a fluid pressure jack 
actuated upon detection of an obstruction to permit the implement to swing 
rearward away from the obstruction. When the obstruction has past, the 
jack is actuated to return the implement to its working position. 
Preferably, the implement can be moved up and down to adjust its depth 
beneath the soil. A second transmitter and detector can be provided to 
sense the position of the implement. Such transmitter and detector can be 
coupled with mechanism for raising and lowering the implement so as to 
maintain a predetermined depth.

DETAILED DESCRIPTION 
With reference to FIG. 1, the crop-sensing cultivator in accordance with 
the present invention includes a support frame 1 that can be hitched to a 
tractor or the like to move the cultivator to till the soil. Frame 1 
rotatably supports an upright shaft 2. A soil-cultivating implement 3, 
such as a blade, extends substantially radially from the drive shaft 2 and 
is secured for rotation with the shaft. The normal working position of the 
implement 3 is illustrated FIG. 4. In such position, the blade extends 
transversely to the direction of travel of the cultivator indicated by the 
arrow 13. 
With reference to FIG. 4, a crank arm 4 projects from the shaft 2 on which 
the implement 3 is supported. The plunger 5 of a fluid pressure jack 6 is 
connected to the crank arm. The cylinder of the jack is pivotally 
supported on the frame 1. A torsion spring 7 biases the crank arm toward 
the cylinder of the jack 6, but normally the crank arm is maintained in 
the working position shown in FIG. 4 by the extended plunger 5. 
A transmitter such as an ultrasound transducer 8 is supported from the 
drive shaft 2 in position to project a sensor beam 9 in a plane parallel 
to and spaced in front of the leading edge of the implement 3. As 
represented in FIGS. 1, 2 and 3, preferably the height and angle of 
inclination of the transducer 8 can be adjusted to adapt the cultivator 
for tending different types of crops. FIG. 1 illustrates one possible 
direction of transmission of the sensor beam for detecting the stem of a 
vine on a raised row. FIG. 2 illustrates a different attitude of 
transmission for detecting the base of a bush. FIG. 3 illustrates 
transmission of the sensor beam beneath the bottom branches of a tree for 
detecting the position of the trunk. 
As shown in FIGS. 1, 2 and 3, the sensor beam 9 is emitted generally 
horizontally above the ground to impinge directly on the obstruction. 
In the preferred embodiment an ultrasound sensor beam is transmitted, but 
beams of different types could be utilized such as infrared, laser or 
radar. 
Preferably, the transducer 8 transmits short pulses of sensor beam at 
uniformly spaced intervals and detects echoes from obstructions in the 
path of the beam. The transducer 8 is coupled to control mechanism 20 
which analyzes the echoes and controls operation of the fluid pressure 
jack 6. In the normal working position of the implement 3 illustrated in 
FIG. 4, an electric solenoid valve is closed to lock the jack with its 
plunger 5 in extended position to maintain the implement extending 
transversely to the direction of travel indicated by the arrow 13. As 
represented in FIGS. 5 and 6, if an obstruction is sensed by detection of 
returning echoes 9', such as the base 14 of a vine, the ports of the jack 
cylinder are opened and, by the action of the torsion spring 7 and the 
resistance of the implement 3 to movement through the soil, the implement 
is automatically retracted away from the obstruction 14 by swinging 
rearward relative to the frame 1. The jack ports remain open so long as 
the obstruction is sensed. With reference to FIG. 7, when the obstruction 
has cleared the implement 3 sufficiently that the obstruction will not be 
engaged by forward swinging of the implement, the jack 6 is actuated to 
extend its plunger to return the implement to its working position. With 
reference to FIG. 4, a limit switch 12 can be provided to sense when the 
implement has returned to its working position, whereupon the ports to the 
jack cylinder are closed, thereby locking the implement in its working 
position until another obstruction is sensed. 
The control mechanism 20 can be adjusted to adjust the effective length of 
the sensor beam, i.e., the maximum distance from the transmitter to the 
obstruction in order for detecting echoes from the obstruction to result 
in automatic retraction of the soil-cultivating implement. Preferably, 
only obstructions in or close to the path of the implement 3 through the 
soil actuate retraction of the implement. By transmitting short pulses of 
ultrasound or equivalent beams, the control mechanism can be adjusted to 
open the ports of the jack cylinder only when echoes are detected within a 
predetermined period following transmission of a pulse. The effective 
length of the beam should be adjusted to be at least slightly longer than 
the length of the implement 3. 
In an alternative embodiment, the jack 6 can be double-acting and the 
control mechanism can actuate the jack to retract its plunger 5 to effect 
the rearward swinging of the implement 3 when an obstacle is detected. 
An additional transmitter 10 (shown diagrammatically in FIGS. 4, 5, 6 and 
7) can be provided to transmit a sensor beam 11 (illustrated in FIGS. 1, 2 
and 3) downward into contact with the soil. Echoes of beam 11 are analyzed 
by the control mechanism to calculate the distance between the additional 
transmitter and the top of the soil, which also provides an indication of 
the depth of the cultivating implement 3 below the soil. With reference to 
FIG. 4, such additional transmitter and its echo-detecting element can be 
mounted on a stationary part of the frame 1 along with a second, upright 
fluid pressure jack 15 effective to raise and lower the shaft 2 and, 
consequently, the implement 3 carried by the shaft. The second 
transmitter-detector can control operation of the second cylinder so as to 
maintain a desired depth of the implement 3.