A CONSTANT DISCHARGE CONTROL DEVICE FOR A SOLID MANURE SPREADER

Abstract: The invention relates to a control device in a compact/solid manure spreader or distributor. The control device comprises sensing means (30-32) for sensing the load, to which the spreading device is subjected when contacting the manure load moving backwardly towards the spreading device, a valve member (35) acted upon by said sensing means in order to maintain the rotation speed of a hydraulic motor driving the conveyor belt substantially reciprocally proportional to the load as sensed, in order to thereby bring about an essentially uniform spreading of the manure in the driving direction of the tractor. The sensing means comprise a lever mechanism (30, 32) with a pulley (31) sensing the tension of a belt (15) driving the spreading rotary rods (8, 9) of the spreading device. The lever mechanism acts upon a valve slide (34) shunting a part of the working flow through a by-pass (49) leading past the hydraulic motor.

Description: A CONSTANT DISCHARGE CONTROL DEVICE FOR A SOLID MANURE SPREADER The present invention relates to a control device in a compact- manure spreader of the type disposed on a carriage adapted to be attached to a tractor and comprising an end-less conveyor belt provided at the bottom of the carriage, a spreading device adapted to spread compact manure and provided in the open rear portion of the carriage, driving means for the conveyor belt, and driving means for the spreading device. As a driving means for the conveyor belt, a hydraulic motor is normally used which is connected to the hydraulic system of the tractor, and as the driving means for the spreading device there is normally used a system comprising pulleys and belts and driven from the power take-off of the tractor. An inconvenience of this known manure spreader resides in the fact that it spreads the manure unevenly in the longitudinal direction, i.e. in the driving direction of the tractor. The uneven spreading of the manure in the longitudinal direction implies that a proportionally greater amount of manure is spread during the first part of the total driving distance for which the manure load is intended, while a proportionally lower amount is spread during the remaining part of the total driving distance. Compare the dashed curve-line in the attached Fig. 6. This inconvenience is due to the fact that the manure load supported by the conveyor belt and moved by the conveyor belt in a backward direction towards the open rear portion of the carriage where the spreading device is positioned, tends to clog when the manure comes into contact with the spreading device. The manure would therefore be compacted due to the movement of the conveyor belt and during this compaction only reduced spreading if any will take place in spite of the fact that the spreading device is operating. Only when the manure has been compacted to a certain extent the spreading device will start to feed out the manure. The manure is then advanced in a compacted state. Once, the spreading of the manure has started, the clogging or banking in front of the spreading device tends to cease and due to this the manure spread thereafter will not have the same density as before. This, in turn, means that a reduced amount of manure will be spread per unit length compared to the spreading during the initial phase. With this known device it is also difficult to control the amount of the output, i.e. the intended amount of solid manure to be spread per unit of area. At present no means are known to avoid the inconvenience due to uneven spreading in the longitudinal direction. To some extent the driver may eliminate this inconvenience by changing the driving speed during the final phase of the manure spreading or by manually adjusting an oil valve in the feeding circuit of the hydraulic motor regulating the speed of the conveyor belt. This procedure is uncertain because the driver does not know the time when the change is to be performed or the necessary degree of the changing. The known device also gives rise to the following inconvenience: When the tractor and carriage have reached the starting position for the spreading of the manure the driver chooses a suitable engine speed and a suitable gear for the intended manure output, and thereafter activates the power take-off and hydraulic system to cause the driving means of the conveyor belt and the spreading device to start working. Now, the conveyor belt and the manure load start moving in a backward direction towards the spreader device and, normally, it will take 20-30 seconds before the manure is ejected from the spreading device. Due to the bad visibility in a backward direction, in particular on larger spreaders, the driver does not observe when the spreading of the manure starts and thus cannot know how long time to wait prior to starting the equipment. Normally the waiting time amounts to about 20-30 seconds, thus a rather extended time difficult to estimate. In order to eliminate this inconvenience the driver may try to calculate the time of a suitable starting moment. Obviously, this method is doubtful and in many cases means that quite a few tens of square meters of ground surface will not be manured as desired. It is a purpose of the present invention to provide a control device eliminating the above-mentioned inconveniences and permitting an even spreading in the longitudinal direction of an adjusted manure output. It is another purpose of the invention to provide a control device permitting even spreading of compact or solid manure in the longitudinal direction and starting to eject the manure within some few seconds after activation of the power take-off. It is another purpose of the invention to produce a control device of the type described initially which, on the one hand, detects the rotary movement of the spreading device and, on the other hand, controls the volume flow of the hydraulic motor in dependence of the detected movement in order to keep the rotary movement of the spreading device constant. When the spreading device is lightly loaded the hydraulic motor driving the conveyor belt is to go fast, which reduces the idle time prior to starting whereas during an increase of the load of the spreading device - due to clogging manure - the hydraulic motor and thus the conveyor belt should work more slowly in order to cause the manure to be spread more evenly in the longitudinal direction while the equipment is moving at a constant speed. It is another purpose of the invention to produce a control device permitting a simple, quantitative adjustment of the desired manure output. According to the invention this is achieved by means of two members, viz. an adjustable valve member for adjustment of the volume flow through the hydraulic motor and the detecting member mentioned above for detecting the rotary movement of the spreading device. According to the invention the detecting member is provided with either a mechanical or an electric control device. Hereinafter, the invention will be explained in detail by reference to the attached drawings in which, Figure 1 is a perspective view of a compact manure spreader provided with a control device according to the invention, Figure 2 is a perspective view of the control device according to the invention, Figure 3 is a basic circuit of the hydraulic system in the control device according to the invention, Figure 4 is a perspective view of a device for electrical sensing of the load of the spreading device, Figure 5 is a block diagram showing the functional blocks in which the signal from the sensing device according to Figure 4 is treated prior to finally being used for controlling the adjustment position of a shunt valve forming part of the hydraulic system, and Figure 6 is a diagram showing the spreading of the manure by means of a conventional manure spreader (dashed curve) and by means of manure spreader provided with the control device according to the invention (full line curv ). In Figure 1 there is shown a manure spreader or distributor comprising a carriage 1 having a spreading device 2 for compact or solid manure (not shown) intended to be loaded on the carriage. The bottom of the carriage is an endless conveyor belt 3 comprising transverse ribs. Such a conveyor belt is well known and is therefore not described in detail. A transverse wall 4 is firmly connected to the conveyor belt and is supported in a substantially vertical position by means of a brace 5. The wall 4 is positioned at the forward side wall of the carraige while the manure is loaded and the purpose of this wall is to advance the manure and to prevent it from shearing. Behind the cover of a box 6 there is positioned the subsequently described control device with the aid of which the purpose of the invention is realized. The power output of the tractor (not shown) is connected to the power input 7 of the carriage for transmission of mechanical power for driving the spreading device. The spreading device comprises a lower roll or rotary rod 8 and an upper roll or rotary rod 9 both provided with projecting arms 10 serving to spread the manure. The rotary rods 8 and 9 of the spreading device are driven by the power output of the tractor via movement transmitting elements (not shown). Both rotary rods 8, 9 rotate in the direction indicated by the curved arrow. The conveyor belt 3 is driven by a hydraulic motor (not shown) connected to the hydraulic system of the tractor via hydraulic conduits (not shown). When the hydraulic motor is activated the endless conveyor belt 3 moves in the direction indicated by the straight arrow at a low speed. A load of manure (not shown) supported by the conveyor belt is accordingly successively moved in a backward direction towards the spreader device 2. The rotary spreader rods 8, 9 throw the manure in a backward direction upwardly and outwardly from the carriage and due to the movement of the conveyor belt the entire manure load has finally been moved towards the spreading device 2 and has been spread-out. During the final phase of the spreading the upper rotary rod 9 tends to throw the manure inwardly into the carriage causing the manure to abut against the transverse vertical wall 4 and to be moved again towards the spreading device 2. In Figure 2, the control device behind the cover of the box 6 is shown. From the power output of the tractor the spreading device 2 is driven by a belt and pulley system comprising a lower pulley 11 driving the lower rotary rod 8, an upper pulley 12 driving the upper rotary rod 9, a driving pulley 13 connected to the power output of the tractor via the above- mentioned movement-transmitting units (not shown), a not driven, straining pulley 14 biased by springs, and a cone belt 15. The endless conveyor belt 3 is driven by a hydraulic motor (not shown) positioned below the bottom of the carriage on the chassis of the carriage. The output shaft 16 causes a sprocket 17 non-rotationally mounted on the shaft 16 to rotate at a high speed. The high output speed of rotation is reduced in a gearing device comprising sprockets 18, 19 and 20 and chains 21 and 22. The sprockets 18 and 19 are non-rotatably mounted on a common shaft and the sprocket 20 is non-rotatably mounted on a rotary rod 23 driving the conveyor belt. It is the function of the straining pulley 14 to stretch the cone belt 15 and is according¬ ly rotatably supported on the one end of a swivel arm 24. The arrangement discribed so far is conventionally applied in manure spreaders of this type. According to the invention the hydraulic motor is of the type having a constant displacement which means that the motor rotates with a certain number of revolutions at a constant volume of the feed flow per unit of time. By controlling the volume flow, the speed of the hydraulic motor and thus also the speed of the conveyor belt can be controlled to a certain volume flow, a certain type of manure and a definite driving speed corresponds a definite manure output. According to the invention a volume- flow controlling valve 25 is used for adjustment of a desired manure output, said valve 25 being varibly adjustable in the feeding circuit of the hydraulic motor. The valve is provided with a control handle 26 for adjusting the volume flow of oil to the hydraulic motor. The control handle has an index marking that runs over a dial 27 on the valve housing. The dial has a number of dial line each corresponding to the amount of the manure output. The rotary movement of the rotary spreading rods 8 and 9 varies depending on the load and its force exerted by the manure on the projecting arms 10 of the rotary rods. This load in turn dependa on the speed at which the conveyor belt is moved, the compactness of the manure etc. According to the invention the load acting on the spreading device is sensed, said load governing the operation of the conveyor belt in order to maintain the rotary movement of the spreading rotary rods 8 and 9 at a constant value to cause a constant amount of manure to be spread per unit of time. This interconnection between the rotary movement of the spreading device and the speed of the conveyor belt is obtained by the aid of the control device shown in Figure 2 comprising a double armed level mechanism having a first arm 30, at the end of which a non-driven pulley is rotatably supported and abuts against the cone belt 15 in the way shown in the Figure. The second arm 32 of the lever mechanism is rigidly arranged in relation to the first arm to be rotated together with the first arm as a unit around a pivot 33 firmly arranged in the chassie or side portion of the carriage. Obviously, when the load acting on the rotary rods 8 and 9 increases, the cone belt will be tensioned at the pulley 31 to move the pulley in a downward direction causing the lever 30, 32 to be rotated as a unit in a clockwise direction. The turning movement acts on a plunger 34 in a shunt valve 35 forming part of the feeding circuit of the hydraulic motor. Thereby the valve is caused to shunt a portion of the feeding flow passing the hydraulic motor which accordingly will work more slowly, which in turn means that the load on the rotary rods 8, 9 is reduced facilitating the rotation of the projecting arms 10 (Figure 1) and causing them to spread a reduced amount of manure. When the load on the rotary rods 8, 9 is reduced, the level mechanism 30, 32 will turn in a counter clockwise direction and the plunger 34 will accordingly move in a direction tending to cut down the shunt flow past the hydraulic motor, causing the volume flow through the hydraulic motor to increase and the motor to increase its speed accordingly. In this way the load on the rotary rods 8, 9 of the spreading device may be held at a constant value. It is thus obvious that the units 30-33 form a mechanism for sensing the load of the spreading device. A mechanism for adjusting the sensitivity with which the plunger 34 of the shunt valve 35 is acted upon is provided in the upper end of the second arm 32 of the lever mechanism. This sensitivity adjusting mechanism comprises a tension spring 36, one end of which is attached to the upper end of arm 32 where the other end is attached to a yoke in the form of a metal rod to which a threaded rod 38 is connected by welding at one end thereof. The threaded rod extends through a hole in a holder 39 which is firmly connected to the side piece of the carriage and has the shape of an angle iron. At the opposite end of the holder 39, a threaded nut or sleeve 40 provided with an adjusting knob is screwed onto the rod. By turning the adjusting knob it is possible to control the force with which the spring 36 acts upon the lever mechanism. If, for example, the spring is strongly tensioned, a very heavy tensioning of the cone belt 15 will be required in order to rotate the lever mechanism and thereby act upon the shunt valve. This means in turn that the rotary rods 8 and 9 may be strongly loaded before the hydraulic motor is acted upon. This in turn means a big manure output. The adjustment of the spring force is read on a graduation scale on a measuring rod 42, one end of which is welded to the yoke 37 and extends through the holder 39 thereby serving as a reference for reading the scale value. The scale on the measuring rod 42 is suitably graduated in steps corresponding to the dial lines on dial 27. If the operating handle 26 is adjusted so that the indicator points at a dial line such as 20 kg/sec. also the adjusting knob 41 shall be rotated to cause the dial line 20 kg/sec. to be adjusted to a position in which the measuring rod 42 passes through the holder 39. Figure 3 schematically shows a hydraulic system for the device according to the invention. Reference numeral 45 designates the hydrualic motor provided on the carriage and driven by the hydraulic system of the tractor. The main feeding conduit to the hydraulic motor 45 is shown by the full-faced line 48. The shunt conduit in which the load- sensing valve 35 is provided has the reference designation 49. A section 50, designated as pilot conduit, is a conduit for adjusting the basic flow to the motor 45, namely the basic flow corresponding to the amount of the desired output. Reference numeral 51 designates a non-return valve. When the spreading device is not loaded the valve 35 is closed. The entire oil flow then goes to the hydraulic motor 45, on the one hand, via the conduit section 50 and, on the other hand, via the one-way valve 51 which is now open. The flow paths are marked by continuous thin arrows for this driving condition. If the load is increased, a portion of the flow is shunted through conduit 49. The flow paths are marked for this driving condition by dashed arrows. When the load is additionally increased, ' there will eventually be no flow at all through the non-return valve 51. The motor 45 is fed only by the basic flow through conduit 50. The flow paths for this state of operation are shown by the heavy continuous arrows. It is a function of he pilot conduit to guide a constant oil flow through the volume-controlling valve 25 irrespective of the load on the hydraulic motor 45 and thus the pressure in the hydraulic conduit. Figure 4 shows a modified embodiment of the invention in which the mechanical sensing element shown in Figure 2 is replaced by an electric sensing element for sensing the load on the spreading device, when it comes into contact with the manure load moving in a backward direction on the conveyor belt towards the spreading device. Instead of the lever system 30-32 and the spring mechanism 36-41 according to Figure 2 this embodiment comprises an electric control circuit described in detail in Figure 5. In place of pulley 31 a sprocket 52 is used and instead of the cone belt 15 a driving chain is used. The sprocket 52 senses the tension of the driving chain and, for this purpose, is mounted on a block 53 which in turn is anchored on a plate 54 attached by screws to the chassis of the carriages 1. Two stretch indicators 55, 56 are provided on the upper side of the block and another two stretch indicators numbered 57, 58 but not shown, are provided on the opposite side of the block 53. Each stretch indicator is in a conventional way attached in each one branch of a Wheatstone-bridge fed with a stabilized reference voltage. Measures have also been taken for temperature compensation of the output signal of the Wheatstone-bridge in order to achieve that this output signal for a certain bending of the block 53 is always equally large independently of ambient temperature. In Figure 5 the circuits for temperature stabilisation and voltage reference are designated 59 whereas the circuits for voltage stabilisation have the designation 60, and the Wheatstone-bridge 61. Figure 5 does not show that the block 59 is actually supplied with voltage from the battery of the tractor. The output signal of the Wheatstone-bridge, the amplitude of which is proportional to the bending of block 53 and therefore to the load of the spreading device enters an active filter 62 of low-pass type. The outlet of the filter is attached to the inlet of an amplifier 63 having a number, in the present case 6, of predetermined amplification degrees which are adjustable by means of a rotary switch. To each degree of amplification corresponds one manure output (expressed in kilograms of manure per second). Each degree of amplification is so calibrated that the zero point lies at +10 V. When the incoming signal to the amplifier is 0 mV the outgoing signal is thus +10 V. When the incoming signal then, for example, amounts to 1 mV to the voltage amplifier 63 the outgoing signal from the amplifier will become, for example, +5 V when the amplification position that corresponds to the highest sensitivi¬ ty of the system (maximum degree of amplification) has been chosen, whereas the same incoming signal 1 mV produces an outgoing signal of 7,5 V from the voltage amplifier 63 when the amplification position corresponding to the second to highest sensitivity of the system has been chosen (second to highest amplification position adjusted by means of the rotary switch). When the incoming signal to the voltage amplifyer 63 is 2 V the outgoing signal becomes 0 V from the voltage amplifier if the highest sensitivity has been adjusted, whereas it will only be 5 V if the second to highest sensitivity has been adjusted. The output signal from the voltage amplifier is supplied to a known proportional control circuit, the outlet of which is connected to a solenoid (not shown) in the shunt valve 35 which preferably is of the proportional type. The proportional control circuit 64 is of the type sensing the position of the valve seat of valve 35 and corrects the position of the valve seat in case a deviation from the correct position has taken place. The proportional control circuit 64 is, for example, of the type sold by Bosch under the designation 0811405010. When the incoming signal to the proportional control circuit 64 is at a maximum value, i.e. 10 V, the total hydraulic flow is shunted past the hydraulic motor and the conveyor belt is at a stand still, whereas in case of 'an input signal to the proportional control circuit of 0 V the proportional control circuit adjusts valve 35 in such a way that no shunt flow takes place, but the total flow passes through the hydraulic motor causing this motor and thus the conveyor belt to move at a maximum speed. All positions therebetween may occur depending on the size of the incoming singal to the proportional control circuit. Figure 6 is a diagram showing the longitudinal distribution of the manure spread by means of the manure spreader, which is provided with the control device according to the invention (full-line curve) as well as the longitudinal distribution of manure spread by means of the same manure spreader but without the control device according to the present invention (dashed curve). The X-axis is a time axis graded in seconds counted from the moment (t=0) when the hydraulic motor is activated and the conveyor belt starts moving, and the Y-axis indicates the number of kilograms of manure spread per second. From the Figure it appears on the one hand that the manure is spread much more evenly by means of the control device according to the invention and, on the other hand that the manure starts being spread almost immediately after the start of the hydraulic motor due to the fact that the hydraulic motor initially works at a very high number of revolutions so that the conveyor belt quickly feeds the manure into contact with the spreading device 2. Normally it will only take about 3-4 seconds from the activation of the hydraulic motor until manure starts being spread, thus a time which is substantially not longer than the time required for the tractor driver to start the hydraulic motor, put in a gear, engage the clutch and start the equipment. The above-described preferred embodiments of the invention can be modified in many different ways. The device is not limited to the specific type of horizontal rotary spreading rods. For example, a number of vertically directed rotary spreading rods may be controlled by means of the control device according to the invention. Instead of the belt and pulley system described herein a system of chains and chain wheels may be used.

Claims: CLAIMS 1. A control device for a solid-manure spreader of the type disposed on a carriage adapted to be attached to a tractor and comprising an endless conveyor belt (3) provided at the bottom of the carriage (1), a spreading device (2) adapted to spread solid manure and provided in the open rear portion of the carriage, driving means (45, 16-23) for the conveyor belt comprising a hydraulic motor having a positive constant dis¬ placement, driving means (11-15) for the spreading device and a first valve member (25) disposed in the feeding circuit of the hydraulic motor for adjustment of a supply flow corresponding to the desired manure output, characterized by sensing means (30-33) for sensing the load to which the spreading device is subjected and contacting the manure load moving backwardly towards the spreading device, a second valve member (35) acted upon by said sensing means to shunt a portion of the support flow through a bypass conduit (49) past the hydraulic motor in order to maintain the rotation speed of the hydraulic motor substantially reciprocally pro¬ portional to the load as sensed. 2. A control device as claimed in claim 1, characterized in that said driving means for the spreading device comprise a belt and pulley system (11-15) or chain and sprocket system driven by the power take-off of the tractor. 3. A control device as claimed in claim 2, characterized in that said sensing means comprise a double armed lever mechanism (30, 32) having a first arm (30) at the one end of which an idling pulley (31) is provided, a second arm (32) which is coupled to the valve slide (34) of the second valve member (35) and a spring mechanism (36-41) for pretensioning the pulley (31) against a driving belt (15) of the spreading device. 4. A control device as claimed in claim 3, characterized in that the spring mechanism comprises means (38-41) for adjusting the spring force at which the lever mechanism is pre-tensioned against the drive belt (15) for the purpose of adjusting the sensitivity of the control system. 5. A control device as claimed in claim 4, characterized in that the spring mechanism (36) is provided at the end portion of the second arm (32) of the lever and extends between this end and a stationary holder (39). 6. A control device as claimed in claim 5, characterized in that the spring mechanism has a graduation scale (42) showing the spring force as set. 7. A control device as claimed in any or some of the preceeding claims, characterized in that said first valve member (25) is provided with a dial scale (27) for setting of the desired manure output. 8. A control device as claimed in claim 6 or 7, characterized in that said scales are graduated to the same units. 9. A control device as claimed in any or some of the preceeding claims, characterized by a transverse wall (4) provided at the conveyor belt and contributing to an even distribution of the manure. 10. A control device as claimed in any or some of the preceeding claims, characterized in that the sensing member comprises stretch indicators (55-58) disposed on a block one end of which is attached to the chassis of the carriage the other end of which supports a sprocket (52) for sensing the load of the driving means. 11. A control device as claimed in claim 10, characterized in that the sensing means in addition comprise a low-pass filter (62) connected to a bridge connection formed by the stretch indicators, and an amplifier (63) attached to the output of the low-pass filter and a proportional control circuit (64) attached to the output of the amplifier, the output signal from the proportional amplifier being adapted to modify the adjustment position of the valve in the second valve means (35). 12. A control device as claimed in claim 11, characterized in that the amplifier has a number of adjustment positions each corresponding to a specific degree of amplification and thus also to a specific manure output (kilograms manure/sec).

Inventors: OERJAN ANDERSSON, OERJAN, ANDERSSON
Applicants: JORDBRUKSTEKNISKA INST, JORDBRUKSTEKNISKA INSTITUTET
Application year: 1990
Main classification: A01C3
IPC codes: A01C3