EP4658461A1 - Material reduction machine with electric infeed - Google Patents

Abstract

A material reduction machine includes a cutting mechanism (124) and a cutting drive system coupled to drive rotation of the cutting mechanism, the cutting drive system including an electric motor. An infeed portion (130) is operable to engage a piece of material to be comminuted by the cutting mechanism and to feed the material to the cutting mechanism. An all-electric infeed drive system is coupled to drive rotation of a feed roller (132) of the infeed portion. A sensor (172) is operable to sense a variable load parameter indicative of load imparted by feeding the piece of material to the cutting mechanism. A controller is coupled to the sensor and configured to receive a signal representing the sensed load parameter, the controller being operatively coupled to the all-electric infeed drive system to adjustably control the feed of the piece of material to the cutting mechanism in response to the signal.

Description

MATERIAL REDUCTION MACHINE WITH ELECTRIC INFEED

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to co-pending U.S. Provisional Patent Application No. 63/482,938, filed on February 2, 2023, the entire contents of which are incorporated by reference herein.

BACKGROUND

[0002] The present invention relates to material reduction machines, for example chippers and grinders, and more particularly to infeed control for cyclic feeding of material into such material reduction machines.

[0003] Chippers typically contain sharp knives that cut material such as whole trees and branches into smaller woodchips. Grinders, on the other hand, typically contain hammers which crush aggregate material into smaller pieces through repeated blows. Example prior art chippers are shown in U.S. Pat. Nos. 10,350,608; 8,684,291; 7,637,444; 7,546,964; 7,011,258; 6,138,932; 5,692,549; 5,692,548; 5,088,532; and 4,442,877; and U.S. Publication No. 2014/0031185, each owned by Vermeer Manufacturing Company; these documents are each incorporated herein by reference in their entirety and form part of the current disclosure. Example grinders are disclosed in U.S. Pat. Nos. 10,350,608; 7,441,719; 7,213,779; 7,077,345; and 6,840,471, each owned by Vermeer Manufacturing Company; these patents are each incorporated herein by reference in their entirety and form part of the current disclosure as well.

[0004] Chippers and grinders often include infeed systems for moving material to the knives or hammers to be processed. Some embodiments of the current invention relate particularly to improved infeed systems for chippers and grinders, to chippers and grinders having such improved infeed systems, and to methods of operation.

SUMMARY

[0005] In one aspect, the present disclosure provides a material reduction machine including a cutting mechanism and a cutting drive system coupled to drive rotation of the cutting mechanism, the cutting drive system including an electric motor. An infeed portion is operable to engage a piece of material to be comminuted by the cutting mechanism and to feed the piece of material to the cutting mechanism. An all-electric infeed drive system is coupled to drive rotation of a feed roller of the infeed portion. A sensor is operable to sense a variable load parameter indicative of load imparted by feeding the piece of material to the cutting mechanism. A controller is coupled to the sensor and configured to receive a signal representing the sensed load parameter, the controller being operatively coupled to the all-electric infeed drive system to adjustably control the feed of the piece of material to the cutting mechanism in response to the signal.

[0006] In another aspect, the present disclosure provides a material reduction machine including an electric power source, a cutting mechanism operable to comminute input material, and a controller. An infeed system of the machine is configured to supply the input material in a cyclic intermittent manner to the cutting mechanism, the infeed system includes a feed roller rotated by an electric motor, the electric motor powered by the electric power source and controlled by the controller, and a gearbox between an output of the electric motor and the feed roller.

[0007] In yet another aspect, the present disclosure provides a material reduction machine including a cutting mechanism and a cutting drive system coupled to drive rotation of the cutting mechanism, the cutting drive system including an electric motor and a cutter drive belt. A first sensor is operable to sense the rotational speed of the electric motor. A second sensor is operable to sense the rotational speed of the cutting mechanism. A controller is coupled to the first sensor and second sensor and configured to receive a first signal and a second signal and thereby calculate a rotational speed differential, the controller being operatively coupled to the cutting drive system to adjustably control the output of the electric motor in response to the rotational speed differential . In some aspects, the controller is programmed to adjustably control the output of the electric motor to maintain a predetermined belt slip limit threshold.

[0008] In yet another aspect, the present disclosure provides a material reduction machine including a cutting mechanism and a cutting drive system coupled to drive rotation of the cutting mechanism, the cutting drive system including an electric motor. An infeed system includes a roller selectively driven to feed material to the cutting mechanism. A controller is programmed to monitor for a dormant condition of the material reduction machine in which the cutting mechanism is driven by the cutting drive system and a predetermined amount of time has elapsed with no cutting demand. Upon identifying the dormant condition, the controller is programmed to shut off the electric motor of the cutting drive system. In some aspects, the cutting mechanism may be completely stopped when dormant. In some aspects, the dormant condition is determined by a feed roller of the infeed system sensed to be below a threshold position and/or the absence of a cutting load on the cutting mechanism. The feed roller may be driven by an electric motor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a rear perspective view of a chipper according to one embodiment of the present disclosure.

[0010] FIG. 2 is an additional rear perspective view of the chipper of FIG. 1.

[0011] FIG. 3 is a front perspective view of the chipper of FIG. 1.

[0012] FIG. 4 is a side view of the chipper of FIG. 1, in use with a log and with a cutaway for illustration.

[0013] FIG. 5 is a side view of the chipper of FIG. 1, showing a cutter clutch assembly in a disengaged state.

[0014] FIG. 6 is a side view of the chipper of FIG. 1, showing a cutter clutch assembly in an engaged state.

[0015] FIG. 7 is an opposite side view of the chipper of FIG. 1.

[0016] FIG. 8 is a rear view of the chipper of FIG. 1.

[0017] FIG. 9 is a perspective view of an infeed roller assembly.

[0018] FIG. 10 is a side view of the infeed roller assembly of FIG. 9.

[0019] FIG. 11 is a cross-section view of the infeed roller assembly of FIG. 9.

[0020] FIG. 12 is an exploded view of the infeed roller assembly of FIG. 9.

DETAILED DESCRIPTION [0021] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0022] Drive System

[0023] FIGS. 1 through 8 illustrate a chipper 100, e.g., a brush chipper according to one embodiment. The chipper 100 includes a processing portion 120 for processing material into smaller pieces and an infeed portion 130 for feeding the material to the processing portion 120. A frame 110 supports (and may form part of) the processing portion 120 and the infeed portion 130. The frame 110 may further include wheels 112 and a hitch 114 to allow travel and transport of the chipper 100. Mobility may not be desirable in all cases, however, and stationary embodiments are also contemplated. The processing portion 120 (FIG. 4) includes a cutting mechanism 124 such as a chipping or cutting drum or a disk cutter. Cutting mechanisms are well known, and any appropriate cutting mechanism (whether now known or later developed) may be used to process material into smaller pieces. The components of the machine, particularly the infeed portion 130 and cutting mechanism 124, are driven by a prime mover system 128, such as an internal combustion engine 125 (e.g., gasoline or diesel), an electric drive motor 126, or a combination thereof, such that the prime mover system 128 is a hybrid system 127 as illustrated. The cutting mechanism 124 can be directly driven (power transfer without a mechanical overload protection device such as a clutch and/or belt) or indirectly driven (power transfer with a mechanical overload protection device such as a clutch and/or belt) by the prime mover system 128. Chipped material is discharged through a discharge portion 129, for example a curved chute.

[0024] Hybrid Power System

[0025] A brief description of the hybrid power system 127 and power transfer system is disclosed below. In the example embodiment of the chipper 100 the hybrid power system 127 is configured such that a portion of the power to operate the chipper 100 is provided by electric drive motor 126 and the other portion is provided by internal combustion engine 125 (example - gas or diesel). For example, the hybrid power system 127 utilizes a 48-volt Lithium Ion battery system 123 capable of 600 amps. The power for the electric portion of the hybrid power system 127 is supplied by a battery system 123 which is an on-board electric power storage unit utilized to store electric power on-board the chipper 100 (i.e., self-contained electrical power, as opposed to connection with grid power or an outside power source). The battery system 123 is connected to electric drive motor 126 and controller 170, along with other components such as feed roller motor 140. In some configurations, for service work (diagnostic) or normal chipping operations, the chipper 100 may be operated entirely by the electric portion of hybrid power system 127, which includes the electric drive motor 126 and the battery system 123. In some configurations, for service work (diagnostic) or normal chipping operations, the chipper 100 may be operated entirely by the internal combustion engine 125. Operating on solely one of the electric portion or the engine

125 may be beneficial for service and diagnostic work. For example, rotating the feed roller 132 can be accomplished without the need to start the engine 125 by utilizing the battery system 123 to power the electric motor 140 of the feed roller 132. The engine 125 and the electric drive motor

126 are connected to the controller 170. The schematically illustrated controller 170 can be physically provided as a single controller or perhaps more likely as a plurality of segregated controllers of an overall control system. For example, there may be individual controllers for: main machine control (e.g., 12V), display control (e.g., 12V), motor controller(s) for electric motors (e.g., 48V).

[0026] Although a hybrid configuration is illustrated in the figures, in some configurations and descriptions herein, the internal combustion 125 can be completely removed, creating a chipper that is powered completely by electricity.

[0027] Power to the cutting mechanism 124 is transferred from electric drive motor 126 and/or engine 125 by drive system components which may include belts, pulleys, drive shafts, clutches, and the like. Engine 125 selectively transfers power to an intermediate drive shaft 136 through engine clutch 137 and engine belt drive system 138. The example embodiment of chipper 100 utilizes a centrifugal engine clutch, although other clutch types, such as an electric clutch, may be utilized in other configurations. In configurations where engine clutch 137 is a centrifugal clutch, the engine 125 does not transfer power to the drive shaft 136 until a threshold speed has been reached (i.e., the centrifugal clutch is selected and designed to engage and disengage at a certain rotational speed of the engine 125). In configurations where the clutch 137 is an electric clutch, the engine 125 does not transfer power to the drive shaft 136 until the clutch 137 is commanded by the controller 170 to engage. The clutch engagement may be triggered in response to a parameter measured by a sensor and reported to the controller 170, e.g., engine rotational speed, drive shaft speed, cutter drum speed, electric motor torque or amperage, and/or a battery state or condition. The controller 170 may include a fixed or adjustable threshold value for such a parameter. Optionally, the clutch 137 may remain disengaged for powering the cutting mechanism

124 solely from the electric drive motor 126. An engine belt drive system 138 (belt and sheaves) may transfer power from an output portion of the engine clutch 137 to the drive shaft 136, although other drive systems have been contemplated, such as driveshafts, gears, or direct connection. In some configurations engine clutch 137 may be omitted, whereby the output shaft of engine 125 is continuously connected to drive shaft 136. Electric drive motor 126 may selectively transfer power to the drive shaft 136 through an additional belt drive system 139 of belt and sheave drive components. Again, other drive systems have been contemplated. For example, electric drive motor 126 may be directly connected to drive shaft 136; alternatively, a clutch (similar to engine clutch 137) is positioned between an output shaft of the electric drive motor 126 and the drive shaft 136 for selectively transferring power from motor 126 to drive shaft 136. In certain embodiments, driveshaft 136 may be omitted from the drive system and the electric drive motor 126 and engine

125 may selectively transfer power (through the utilization of clutches) to the drive shaft 141 of the cutting mechanism 124.

[0028] An example operation of the hybrid power system 127 includes operating the engine 125 and the electric drive motor 126 in parallel. During operation of the hybrid power system 127, the electric system (including the battery system 123 and electric drive motor 126), or the engine 125, or both may provide power to components of chipper 100 depending upon certain conditions. In a nonlimiting example, and for simplicity, assume in the following example that the electric drive motor 126 and the engine 125 are connected at a 1: 1 speed ratio (such as by a belt drive connecting respective drive shafts thereof) (i.e., if the engine turns at 2500 rpm, then the electric drive motor 126 will turn at 2500 rpm). For conditions where the chipper 100 is preparing for chipping, or when a chipping operation is completed, or when no load or a minimal load below a threshold is present, the controller 170 will command the engine 125 to operate at high idle (e.g., 3800 rpm). Simultaneously, the electric drive motor also operates at the engine’s high idle speed (e g., 3800 rpm). However, the controller 170 does not command the electric drive motor 126 to begin powering until a motor engagement threshold speed has been reached, the motor engagement threshold speed being below the high idle speed (e.g., 3600 rpm). During the “no load” condition (where the electric drive motor 126 is being driven by the engine 125 above the motor engagement threshold speed) the control system implemented by the controller 170 sets the electric drive motor 126 to operate as a generator to charge the battery system 123 (regeneration mode).

[0029] Brush chippers typically have low duty cycles which allows time for the engine 125 to charge the battery system 123. For example, the chipper 100 may require manual feed of input material, and furthermore, may start and stop a plurality of times to comminute the material as described further below. The charging of the battery system 123 is limited to certain rate, such as 200 amps. In some constructions, the battery system 123 is charged at this maximum rate, in some or all charging conditions. Alternatively, the charging rate of the battery system 123 is scaled based on state of charge (SoC) of the battery (e.g., averaged to a setpoint). This may prevent drawing too much power from the engine 125 and prevent pulling high current when not necessary, to increase battery life. The end result is a SoC that oscillates around a value during chipping, charging more aggressively when the battery SoC dips too low (below a threshold), and charging at a reduced rate when the battery SoC is higher than a threshold. Generally, with this recharging system the torque the electric drive motor 126 pulls for recharging varies (e.g., proportionally or at least in steps) in relation to how far the battery system 123 is from a desired/threshold level of recharge. Therefore, the torque the electric drive motor 126 pulls for recharging may be a first higher amount when the battery system 123 is below the desired/threshold level of recharge and may be a second lower amount when the battery system 123 is above the desired/threshold level of recharge. The recharging system may leave some buffer space in the battery SoC corresponding to energy generated when regeneratively braking the cutting mechanism 124 to a stop (which creates a high current flow). The buffer space may be dependent on the model of battery used, as some battery models at higher charge states may not be able to accept current as fast due to a lower voltage difference between the generated voltage and the battery state. Similarly, the buffer space in the battery SoC may be useful in a configuration where the chipper 100 is entirely powered by the battery system 123 (i.e., the engine 125 is not included). [0030] When the hybrid power system 127 of the chipper 100 begins to experience a load, such as when material is introduced into the cutting mechanism 124, the speed of the electric drive motor 126 and the engine 125 will begin to drop. When the engine and motor speed hits the motor engagement threshold (e.g., 3600 rpm), the controller 170, according to its programmed algorithm) commands the electric drive motor 126 to cease charging (exit regeneration mode) and begin driving by pulling stored electricity from the battery system 123 such that the electric drive motor 126 and the engine 125 are both contributing to power the chipper 100, particularly the cutting mechanism 124. The feed roller 132 continues rotating to feed material toward the cutting mechanism 124 until all material has been chipped or a stop threshold is reached. The stop threshold can be provided in terms of a controller-monitored parameter indicative of load imparted by feeding the material to the cutting mechanism 124. As such, the stop threshold may be an engine speed, such as 2400 rpm, and/or the stop threshold may be a current output from the battery system 123 to the electric motor 126, such as 600 amp. Alternatively, or in combination, the stop threshold can be a limit or threshold on the current drawn by the feed roller motor 140 (e.g., 50 amps). Alternatively, or in combination, the stop threshold may be based on the speed of the cutting mechanism 124. When a stop threshold has been reached, as determined by the controller 170 upon receiving a corresponding signal from a sensor, the chipping operation is ceased by stopping and/or reversing the direction of the feed roller 132 to prevent material from comminution by the cutting mechanism 124, which allows the engine 125 and the electric drive motor 126 to recover (increase in speed) until a restart threshold is reached (e.g., 3500 rpms), at which point a subsequent chipping cycle begins as the feed roller 132 begins rotating to feed material to the cutting mechanism 124. This cyclic intermittent comminution pattern continues until the input material (which can be a singular element 10 such as the log shown in FIG. 5, or a combination of elements) is fully fed through the cutting mechanism 124. While the above description makes direct reference to the engine 125 and the electric drive motor 126 and variable load parameters associated with each one, it is also contemplated that particular aspects of the above load- responsive cyclic cutting may also apply where only one of the engine 125 and the electric drive motor 126 is operating - either as a designated mode of the hybrid power system 127 or an embodiment in which only one of the engine 125 and the electric drive motor 126 is provided in the chipper 100. [0031] Power transmission to the cutting mechanism 124 may be stopped by: (1) disengaging cutter clutch assembly 143, or (2) discontinuing to power electric drive motor 126 and shutting off the engine 125. Of course, if the chipper 100 is provided without the engine 125, the power transmission to the cutting mechanism 124 may be stopped simply by discontinuing to power the electric drive motor 126. The fastest way to decelerate the cutting mechanism 124 may be accomplished by keeping the cutter clutch assembly 143 engaged while shutting off the engine

125 and switching the electric drive motor 126 to regeneration mode in which the rotation of the electric drive motor 126 is used to recharge the battery system 123. In this case, the regeneration mode may stay engaged until the drive motor speed is zero.

[0032] As noted above, the electric drive motor 126 may be connected to directly drive the cutting mechanism 124. In such a configuration of the chipper 100, the electric feed roller motor 140 may operate in accordance with the preceding disclosure to limit cutting loads by performing intermittent cutting cycles. In particular, the electric drive motor 126 can be controlled by the controller 170 based on a load sensed on the cutting mechanism 124. However, the electric drive motor 126 may also be protected by dedicated overload controls within the controller 170. Such overload controls can be provided to any/all of startup, stopping, normal chipping. For example, the controller 170 can be programmed with a threshold torque limit (which may also be implemented as a threshold current limit, by way of the known relationship between current and torque). Power to the electric drive motor 126 may be cutoff in the event that an input from a sensor to the controller 170 indicates that the threshold torque limit is reached. Such controls may work in tandem with control of the electric feed roller motor 140 described elsewhere herein so that material infeed toward the cutting mechanism 124 is stopped upon the controller 170 identifying the threshold current at the limit. Such a threshold used by the controller 170 can prevent damage to the electric drive motor 126, a drive coupling between the electric drive motor

126 and the cutting mechanism 124, and/or the cutting mechanism 124.

[0033] Economy Mode

[0034] With the hybrid power system 127, or select components or variations thereof, it is possible to operate in an economy mode. Economy mode is achieved by having the controller 170 shut off the engine 125 and/or the electric drive motor 126, and/or reducing the speed of the engine 125 and/or the electric drive motor 126 in certain conditions, such as when no material is determined to be in the infeed portion 130. In other words, because an operator has not inserted material, the chipper 100 is running idle or dormant, rather than being actively used. The economy mode is automatically engaged by the controller 170, based on sensed parameter(s) indicating that chipping activity is not currently in demand. Depending upon the desired operation and configuration of the machine, multiple variations of economy mode may be available. Economy mode(s) may be implemented in a manner similar to those disclosed within Vermeer Manufacturing Company’s U.S. Patent No. 7,597,279, U.S. Patent No. 7,624,937, and/or U.S. Patent No. 7,637,444, the entire contents of which are incorporated by reference herein. In economy mode, the engine off condition may not occur until the battery system 123 is charged to a desired amount (e.g., a predetermined threshold charge level). In other words, the chipper 100 may only selectively enter the economy mode, although other conditions are met, based on a charge level of the battery system 123.

[0035] A first example of economy mode exists when the position of feed roller 132 is used to determine if material is present in the infeed region. In this configuration, when the feed roller 132 is in its lowest position, as sensed by sensor 172, the feed roller 132 may be continuously rotating to allow material to be fed toward the cutting mechanism 124, however, since the feed roller 132 is in its lowest position, the cutting mechanism 124 may be operated at a minimum speed (minimum running speed or zero speed) until feed roller 132 moves above a threshold position and/or load is sensed on cutting mechanism 124 (either of which is indicative of a load or demand on the chipper 100). In configurations where the speed of cutting mechanism 124 is zero and when the feed roller 132 is below the threshold position, the engine 125 and/or the electric drive motor

126 may be shut off. In configurations where the speed of the cutting mechanism 124 is held at a minimum running speed when the feed roller 132 is below the threshold position, one of the engine 125 or the electric drive motor 126 may be shut off, or both may be operated at a minimum running speed (e.g., corresponding to the predetermined low idle speed of the engine 125 — in any case, a running speed less than a predetermined operational cutting speed, and in some cases a lowest available speed setting). When the feed roller 132 moves above a threshold position, the speeds of the feed roller 132 and the cutting mechanism 124 may be increased to operational speeds for chipping. Once dormant (determined by the feed roller 132 dropping below the threshold position and/or no load sensed on the cutting mechanism 124) for a predetermined amount of time, the cutting mechanism 124 can return to the minimum speed, allowing for the electric drive motor 126 and the engine 125 to be operated at the minimum running speed or simply shut off. The economy mode repeats this cycle as necessary to conserve battery power and/or fuel and reduce noise.

[0036] As an alternative economy mode trigger, the presence or absence of load or demand can be determined by monitoring with the controller 170 whether material is engaged by the feed roller 132. Such a determination can be sensed with the current of the feed roller motor 140. When current of the feed roller motor 140 is below a threshold value, which may be at or near zero corresponding to no infeed material (e.g., less than 5 amps), the controller 170 sets into the economy mode, as described above to reduce consumption. When the feed roller motor 140 draws current above the threshold value, the controller 170 exits the economy mode. In conditions where feeding material with the feed roller motor 140 does not add significant amperage for discerning the current in relation to the threshold value, the amperage could be amplified by allowing the feed roller motor 140 to drive the feed roller 132 and push material against the stopped cutting mechanism 124 (creating higher current at the feed roller motor 140). Then the feed roller 132 reverses slightly to avoid starting the cutting mechanism 124 while material is against it, but not so far as to let the material exit the feed roller 132. Then the cutting mechanism 124 is brought up to speed before restarting the feed roller 132 to rotate forward to feed material toward the cutting mechanism 124. In a configuration where the cutting mechanism 124 rotates at reduced speed during economy mode, detection of load on the cutting mechanism 124 can be used as the trigger to exit economy mode. The feed roller 132 feeds material to the cutting mechanism 124, the controller 170 identifies the load by an appropriate sensor connected therewith, and the feed roller 132 reverses slightly to allow time for the cutting mechanism 124 to accelerate to normal chipping speed.

[0037] In economy mode, the engine 125 may recharge the battery system 123 whenever the electric drive motor 126 is not needed for powering the cutting mechanism 124. The battery system

123 may also be recharged by deceleration of the cutting mechanism 124 when slowing or stopping the cutting mechanism 124 (e.g., when entering the economy mode). The controller 170 may operate to maximize regenerative charging. In a configuration in which the cutting mechanism

124 is stopped during economy mode, recharging of the battery system 123 may be accomplished with the cutter clutch assembly 143 in a disengaged state so that the electric drive motor 126 can be run as a generator without mechanical connection and rotation of the cutting mechanism 124. In further constructions, the chipper drive system may be all-electric (e.g., including the electric drive motor 126 but not the engine 125), and all applicable features of the economy mode remain as disclosed above.

[0038] Slip Monitoring

[0039] Electric motor torque is generally consistent through its speed range (from minimum rotation speeds to maximum rotation speeds). This may allow for a shorter time to get the cutting mechanism 124 up to chipping speed. For example, the hybrid drive system 127, or the electric drive motor 126 alone, may be capable powering the cutting mechanism 124 from zero rpm to chipping speed (thus, completing a start-up) in about 10 seconds, where a comparable sized traditional brush chipper having only an internal combustion engine may take 30 seconds. However, the driveline must be capable of transferring the power. In some embodiments the motor torque from the electric drive motor 126 is limited to less than its full capability by the controller 170 to prevent drive line issues, such as belt slip. In some constructions, the belt slip can be monitored by the controller 170 by comparing the rotational speed of the drive motor 126 and the rotational speed of the drive shaft 141 of the cutting mechanism 124 to calculate the amount of belt slip (e.g., as a percentage difference from transmission without any slip). The controller 170 may take into account a known “no slip” speed ratio defined between the electric drive motor 126 and the drive shaft 141 of the cutting mechanism 124 (i.e., from a pulley size ratio between drive and driven pulleys). Then, the controller 170 can control the output of the electric drive motor 126 to keep the belt slip within a predefined range during a start-up (e.g., 50% or less, 40% or less, 30% or less, 20% or less, 15% or less, 10% or less). The controller 170, with fast response and processing times, may initially identify 100% slip at the very onset of starting the electric drive motor 126 since the cutting mechanism 124 will not respond with instantaneous rotation. This special case notwithstanding, slip is monitored by the controller 170 and actively managed to not exceed the threshold slip value while applying maximum allowable amps (i.e., torque) to the drive motor 126 in order to increase the speed of cutting mechanism 124 as quickly as possible, with the goal being to minimize the time to get the cutting mechanism 124 up to chipping speed. In other constructions, the slip is monitored by the controller 170 to not exceed the threshold slip value while running speed control of the electric drive motor 126 rather than torque control (i.e., running at maximum allowable speed of the drive motor 126, within the constraint of the slip threshold, in order to get the cutting mechanism 124 to chipping speed as quickly as possible. Further yet, the electric drive motor 126 may be controlled to pulse ON/OFF a plurality of times (e.g., without actively controlling torque or speed in relation to belt slip) to effect a smooth startup of the cutting mechanism 124. In some constructions, a startup routine may be adapted from Vermeer’s U.S. Patent Application Publication No. 2023/0149942, the entire contents of which are incorporated by reference herein. Active belt slip management by controlling the electric drive motor 126 may be particularly advantageous in an alternative construction in which there is no clutch (clutch mechanism 143 is not present), to enable selective connection and disconnection between the drive motor 126 and the cutting mechanism 124.

[0040] Although particularly useful during startup of the cutting mechanism 124 to the chipping speed, belt slip monitoring can be useful in other scenarios as well. For example, belt slip monitoring can take place during normal chipping operations, either continuously or periodically. During the course of performing the normal cutting cycles, there may be a certain amount of belt slip that is normal or expected in a fully functional, as-new chipper 100. A belt slip threshold during chipping operation can be the same as or different from the belt slip threshold during a startup (e.g., belt slip threshold during chipping can be 50% or less, 40% or less, 30% or less, 20% or less, 15% or less, 10% or less). The expected or allowable amount of belt slip can be programmed to the controller 170 or learned by the controller 170 when the chipper 100 is put into service. As the chipper 100 experiences wear from prolonged use, the amount of belt slip will increase, and the controller 170 will observe and identify the increased amount of belt slip. Increased belt slip may also be identified due to a component failure, unexpected event, etc. When the controller 170 identifies an excessive amount of belt slip, based on exceeding a stored threshold or an abrupt change for example, it may trigger an alert and/or change the operational status of the chipper 100 (e.g., prevent or alter chipping with the cutting mechanism 124). The controller 170 may also issue predictive warnings as the calculated belt slip amount gradually approaches the stored belt slip limit threshold.

[0041] As will be apparent to one of ordinary skill in the art, a belt drive system includes a flexible belt wrapped partially around at least a driving pulley and a driven pulley - sometimes referred to as sheaves. Example belt drives are shown between the intermediate drive shaft 136 and each of the engine 125 and the electric drive motor 126, and also between the intermediate drive shaft 136 and the cutting mechanism drive shaft 141. Belt slip may be monitored for an individual or compound belt drive. The belt is selectively engageable with the driving and driven pulleys to transfer rotational power. A tensioner and/or a clutch may optionally be provided. When engaged and transferring power, speeds of the driving and driven pulleys can be monitored, by tracking with respective sensors and reporting signals to the controller 170. In some constructions, belt slip is determined by a speed comparison between the prime mover element (e g., electric drive motor 126) and the ultimate driven element (e.g., cutting mechanism 124). In other constructions, one or more intermediate components may be used in monitoring belt slip. As noted above, a known “no slip” speed ratio may be factored into the belt slip equation by the controller 170. A slip percentage (SP) may be calculated as follows: SP = 100 * (driving RPM - driven RPM) / driving RPM. However, where a known speed ratio exists between the driving component and the driven component (such as through the use of different size pulleys for a belt drive, or gearboxes, etc. are present in the drive system between the drive and driven shafts), the ratio must be taken in to consideration, therefore the calculation for slip percentage would be: SP = 100 * (driving RPM - driven RPM * drive ratio) / driving RPM. Two separate examples are given below, both resulting in 10% belt slip:

[0042] In a 1: 1 drive ratio system: SP = 100 * (1000 RPM - 900 RPM *1) / 1000RPM = 10%

[0043] In a 2: 1 drive ratio system: SP = 100 * (1000 RPM - (450 RPM * 2) / 1000RPM = 10%

[0044] The system may use closed loop control, i.e., PID control. For example, the controller

170 may command the motor 126 to ramp up speed until it encounters a slip threshold, at which point the controller 170 maintains the motor speed until slip is reduced, or reduce the motor acceleration rate until slip is reduced. There may be a time delay between taking slip samples, such as 100 milliseconds.

[0045] Alternative to a belt drive, or in combination with a belt drive, some drive system configurations may utilize alternative overload protection devices, such as a clutch. The clutch may be electric, hydraulic, or other friction clutches that are capable of engagement and disengagement of a power source to a driven component. Additionally, the clutch may have a variable engagement, meaning the clutch can transfer power between the drive component and the driven component at a variable rate and may have at least one partially engaged state. Additionally, the clutch, although engaged, may slip during certain load conditions, leading to a difference in the driven shaft speed compared to the drive shaft speed. Such clutches may be monitored for slip by comparing the speed of a driven rotating component (e.g., drive shaft 141, clutch output, etc.) to the speed of a driving rotating component (e.g., engine 125, electric drive motor 126, intermediate drive shaft 136, clutch input, etc.). Thus, the above details of belt slip calculations can be adapted or generalized to other driving and driven components as would be understood by one of ordinary skill in the art, without fully repeating the entire disclosure. Similar to the belt system described above, the electric drive motor 126 may be controlled to limit slip to a desired slip threshold, such that the above described features of belt slip monitoring can be more generally applicable to slip monitoring. Where a clutch is present in the drive line, the controller 170 can selectively operate the clutch (i.e., changing state or engagement condition between disengaged and engaged) in conjunction with active control of the electric drive motor 126, or in lieu thereof.

[0046] Cutter Clutch Assembly

[0047] In the example embodiment of chipper 100 the electric drive motor 126 is constantly coupled with the drive shaft 136. Drive shaft 136 has selective power transfer to cutting mechanism 124 through cutter clutch assembly 143. Cutter clutch assembly 143 includes a drive shaft 136, a drive shaft pulley 148, a clutch linkage 144, a clutch actuator 145, a cutter drive belt 146, a clutch arm 149 and a clutch arm pivot 150 (FIGS. 1, 5, and 6). The drive shaft pulley 148 is attached to a movable end of the drive shaft 136. The drive shaft 136 may be composed of multiple segments, the segments may be connected by couplers that allow for misalignment, such as continuous velocity joints (CV joints) and/or universal joints (U-joints). The segments of the drive shaft 136 may be rotationally secured to the frame 110 by bearings with housings, such as pillow block bearings. The moveable end of the driveshaft 136 is pivotally attached (i.e., by a bearing and housing) to the clutch arm 149. The clutch arm 149 pivots about the clutch arm pivot 150. FIG. 5 shows clutch assembly 143 in a disengaged state when the clutch actuator 145 is retracted which loosens the connection of the cutter drive belt 146 to the cutter drive pulley 147 and the drive shaft pulley 148 through movement of the clutch linkage 144 and rotation of the clutch arm 149 such that power is not transferred from the driveshaft 136 to cutter mechanism 124. Conversely, FIG. 6 shows the cutter clutch assembly 143 in an engaged state when clutch actuator 145 is extended which tightens the connection of cutter drive belt 146 to the cutter drive pulley 147 and drive shaft pulley 148 through movement of the clutch linkage 144 and rotation of the clutch arm 149 such that power is transferred from driveshaft 136 to the cutter mechanism 124. As can be seen by the comparison of FIGS. 5 and 6, the clutch linkage 144 is an over-center linkage, with the over-center engaged position of FIG. 6 obviating the need to maintain energization of the clutch actuator 145 for engagement. The clutch linkage 144 contacts a fixed stop 180 in the engaged position of FIG. 6. The cutter clutch assembly 143 may be engaged and disengaged by the controller 170 based upon input from other components, such as feedback from the hybrid drive system 127, the feed roller position sensor 172, feed roller stall sensing, and/or feed control bars 176. In some configurations, the cutter clutch assembly 143 may be manually engaged and disengaged by an operator, through the use of a control such as a lever or button. Engaging the cutter clutch assembly 143 transfers powers from the drive shaft 136 to the cutting mechanism 124. Disengaging the cutter clutch assembly 143 prevents power from transferring to the cutting mechanism 124.

[0048] Infeed Portion and Feed Roller

[0049] The infeed portion 130 is upstream of the processing portion 120 and includes a feed roller 132 (FIGS. 9-12). The feed roller 132 is selectively actuated by one or more feed roller motors 140 (e.g., electric motors) as shown in FIG. 9. The feed roller motor(s) 140 are driven by electricity, which may be provided by battery system 123. Although the feed roller 132 can be allelectric driven, it is conceived that that the feed roller 132 or other feed roller(s) can be driven in part or wholly by a hydraulic motor from an on-board hydraulic system in other constructions. The drive state (e.g., including on and off states, forward, and optionally reverse state, and selected speed) of the feed roller motor 140 is controlled as part of a control system 175 (FIG. 3). A controller 170 of the control system 175 may be in direct or indirect control of the feed roller motor 140, among other components of the chipper 100. The feed roller 132 operates at a fixed or variable rotational speed. Adjusting feed roller speed can change chip size thereby, the user can select a preferable chip size by adjusting feed roller speed, which may be preset and programmed into the controller, being selectable by the operator. Similarly, the feed roller speed may be a variable setting selected by the operator. Movable feed control bars 176 are examples of operator controls that allow for stopping, forward, or reverse rotation of feed roller 132. [0050] The infeed portion 130 may further include an infeed floor 135. In some embodiments, the feed roller 132 is movable toward and away from the infeed floor 135, for example feed roller 132 may be mounted on feed roller arm 133 (FIGS. 7 and 9-12) that pivots on shaft 136 about feed roller arm pivot 134, gravity may provide downforce for feed roller 132. Raising the feed roller 132 to a service position may be accomplished manually with an appropriate lifting device, alternatively electric and/or hydraulic actuators (not shown) may selectively raise and lower the feed roller 132 relative to the infeed floor 135 under the command of the controller 170. During a chipping operation, the height of the infeed material 10 combined with rotation of the feed roller 132 against material 10 may raise the feed roller 132 as the feed roller 132 climbs material 10 by pivoting on feed roller arm 133 about feed roller arm pivot 134, thus, a variable infeed passageway area (FIG. 4) is defined between the feed roller 132 and the infeed floor 135. In some embodiments, gravity (the weight of the feed roller 132 and feed roller arm 133) provides the gripping or crushing force exerted on the material 10 being fed into the chipper 100. Alternatively, the gripping or crushing force exerted by feed roller 132 on the material 10 may be increased or decreased by actuators (electric and/or hydraulic) (not shown) that connect to the feed roller arm 133, such as the system described in U.S. Patent No. 8,684,291, the entire contents of which are incorporated by reference herein. These actuators may be controlled sufficiently to allow the feed roller 132 to float under certain circumstances. The infeed floor 135 can be provided by a conveyor (not shown), for example in a whole tree chipper, thus providing a second feed system that works cooperatively with the feed roller 132 in delivering the material 10 to the cutting mechanism 124. Whether or not the infeed floor 135 includes a conveyor, the infeed portion 130 can include a second feed roller (not shown), or lower feed roller, positioned below the illustrated feed roller 132, which may be controlled similar to feed roller 132. Output from a sensor 172 (FIG. 4) indicates the position of the feed roller 132, for example with respect to a neutral position or with respect to the infeed floor 135. Sensor 172 may be connected to controller 170.

[0051] Infeed Control System

[0052] The control system 175 may initiate a chipping process by operator input (a control button) and/or when material is determined to be in the infeed portion 130, among other conditions that must be met, such as adequate speed of the cutting mechanism 124, the position of the infeed control bars 176, and all other controls and sensors that must be in a condition for chipping. Operator controls may be situated on the chipper 100 or a remote-control unit, such as remote 185 (FIG. 3).

[0053] The functionality of the chipper 100 can be carried out without the need for hydraulic power. Brush chippers are commonly sized according to the maximum infeed opening and/or maximum diameter of material that can fit in the infeed roller gap. It is common for chippers to have a powered infeed roller, particularly for chippers capable of chipping material six inches in diameter and larger. It is common to use a hydraulically driven feed roller due to the high torque and low speed required for the infeed roller. However, the hydraulic system to drive the feed roller may be the only hydraulic system on the chipper, which necessitates certain components and complexities (e.g., hydraulic motor and supply of pressurized fluid, along with over-pressure detection and mitigation) that could otherwise be eliminated. By discarding hydraulic-driven infeed, actuator(s) for rotation of the feed roller 132 may be solely electric, i.e., the electric motor 140. Electric feed roller motor 140 may be powered by the battery system 123 and controlled by the control system 175, including the controller 170. The drive unit formed by the combination of the feed roller motor 140 and the gearbox 151 is directly connected to the feed roller shaft 156, as illustrated in FIG. 12 and described below.

[0054] The feed roller 132 is driven by the electric feed roller motor 140, and the gearbox 151 is located between the output shaft 140A of the electric feed roller motor 140 and the feed roller 132. The rotation axis of the electric feed roller motor 140, as defined by the motor output shaft 140A, can be coincident with the rotation axis of the feed roller 132, as defined by its axis 156. The gearbox 151 functions to reduce the speed of electric motor 140 to the desired rotational speed of feed roller 132. The output shaft 164 of gearbox 151 then connects to feed roller 132. Typical electric motor speeds may be 1500 rpm through 3000 rpm. Typical feed roller speeds may range from 15 rpm to 60 rpm. The gearbox 151 may also increase the torque available for rotating the feed roller 132. For example, a chipper having the capability to chip material up to 10 inches in diameter may require an infeed pulling force of up to about 1260 pounds of force, which may use 5-50 amps at 48 volts DC. Larger brush chippers require larger infeed pulling forces and possibly multiple infeed roller motors and higher amperage. As another example, a chipper having the capability to chip material up to 21 inches in diameter may require 11,170 pounds of force, which may use 5-75 amps at 350 volts DC. The gearbox 151 helps allow for an efficient sized electric feed roller motor 140. For example, the electric feed roller motor 140 may only require 40 amps. An example ratio of the gearbox input rpm to gearbox output rpm is 32: 1. The gearbox 151 may be incorporated into the housing of the electric feed roller motor 140 or attached as a separate component. In addition to or in lieu of the gearbox 151, the electric feed roller motor 140 can drive the feed roller 132 through a power transmission including a chain drive or a belt drive. Even though the illustrated embodiments show a hybrid power system, it is also contemplated that the electrically driven feed roller 132 can be incorporated into a chipper utilizing electricity as the sole power source (from batteries or an external electric supply) or into a chipper utilizing an internal combustion engine as the sole power source.

[0055] FIG. 12 shows an exploded view of a mounting configuration for the feed roller 132, the feed roller arm 133, the infeed motor 140, and the gearbox 151. A bearing housing 159 is attached (welded or with fasteners) to the feed roller arm 133. The feed roller shaft 156 passes through the bearing housing 159. The feed roller shaft 156 is rotationally mounted to the bearing housing 159 by a bearing 158, which is secured by a snap ring 157. The feed roller shaft 156 may have external features configured to cooperate with the bearing 158. The bearing housing 159 may have internal features configured to secure the bearing 158 and the snap ring 157. The feed roller 132, particularly a hub 132A thereof as shown in FIG. 9, is secured to the feed roller shaft 156 by a coupler 155. The coupler 155 may be a Ringfeder® coupling device. The feed roller motor mount 160 may be secured to the feed roller arm 133 by fasteners 152. The feed roller motor 140 is attached to the feed roller shaft 156 (thereby to feed roller 132) by a motor coupler 162. The motor coupler 162 is rotationally secured to the feed roller shaft 156 and the gearbox output shaft 164 (e.g., a sprocket) through corresponding male and female components that may utilize keys 161 and 163 to rotationally lock the components. In the example configuration, the gearbox 151 is incorporated into the housing of the feed roller motor 140. The output shaft 164 is the rotating output shaft of the drive unit formed by the combination of the feed roller motor 140 and the gearbox 151 or alternative power transmission. The output shaft 164 rotates relative to the housing or housings of the gearbox 151 and the feed roller motor 140. The housing(s) of the gearbox 151 and the feed roller motor 140 is/are attached (e.g., by fasteners) to the feed roller motor mount 160. The configuration of FIG. 12 illustrates one example of directly connecting (without a clutch or additional power transmission, such as a belt drive or chain drive) the feed roller 132 to the gearbox 151 and/or the feed roller motor 140. This configuration allows for forward or reverse rotation of the feed roller 132.

[0056] A challenge associated with an electrically driven infeed roller when compared with a traditional hydraulic infeed roller system is the need to control the speed of the electric driven feed roller 132 compared to the drum speed of the cutting mechanism 124. On a hydraulic infeed system, in which the hydraulic system is powered by the engine, when the engine speed drops due to loading caused by material being processed by the cutting mechanism, a hydraulically-powered feed roller inherently slows because hydraulic flow is reduced due to the drop in engine speed since the hydraulic pump is driven by the engine. This corresponding reduction in speed may be beneficial to prevent material from contacting the cutter mechanism which may cause an overload condition or inconsistent chip sizes. Conversely, with an electrically-driven infeed system as described above, the speed of the feed roller 132 is not inherently affected by the speed of the cutting mechanism 124 and will, unless otherwise controlled, continue feeding at the same speed even when the cutting mechanism 124 slows due to cutting load - to the detriment of the machine/process. Therefore, the control system 175 of chipper 100 may be configured to monitor the prime mover speed (i.e., the running speed of the engine 125 and/or the running speed of the electric drive motor 126) and/or the speed of the cutting mechanism 124 and make corresponding adjustments to the speed of the electrically-driven feed roller 132. As mentioned, the rotational speed of the feed roller 132 is monitored and controlled by control system 175. Rotational speed of feed roller 132 may be determined by the speed of the electric feed roller motor 140 and/or a speed sensor (not shown) connected to the controller 170. A cutting mechanism speed sensor 165 is connected to the controller 170 (FIG. 3). The running speeds of the engine 125 and/or electric drive motor 126 can be detected by respective speed sensors (not shown). Therefore, the electric infeed system allows variability in controlling the speed of the electric feed roller motor 140 as mentioned above, i.e., the motor speed (therefore the feed roller speed) is varied based on machine parameters, such as cutting mechanism speed and/or prime mover speed (either of which is a variable load parameter indicative of load on the cutting mechanism 124 imparted by feeding the piece of material to the cutting mechanism 124). Additionally, the controller 170 connected to the electric infeed system monitors, controls, and utilizes electrical current to limit infeed force and monitor for stall events. For example, if current to the electric feed roller motor 140 (as sensed by a sensor and reported to the controller 170) exceeds a threshold, such as 50 amps, the controller 170 may be programmed to stop current flow or reduce current to the electric feed roller motor 140, and/or the controller 170 may reverse the direction of rotation of the electric feed roller motor 140; in either condition, the controller 170 may also trigger an operator alert.

[0057] One of ordinary skill in the art will appreciate that many of the various electrical and mechanical parts discussed herein can be combined together or further separated apart. The controller 170 may include one or more electronic processors and one or more memory devices. The controller 170 may be communicably connected to one or more sensors or other inputs, such as described herein. The electronic processor may be implemented as a programmable microprocessor, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGA), a group of processing components, or with other suitable electronic processing components. The memory device (for example, a non-transitory, computer-readable medium) includes one or more devices (for example, RAM, ROM, flash memory, hard disk storage, etc.) for storing data and/or computer code for completing or facilitating the various processes, methods, layers, and/or modules described herein. The memory device may include database components, object code components, script components, or other types of code and information for supporting the various activities and information structure described in the present application. According to one example, the memory device is communicably connected to the electronic processor and may include computer code for executing one or more processes described herein. The controller 170 may further include an input-output (“I/O”) module. The I/O module may be configured to interface directly with one or more devices, such as a power supply, sensors, displays, etc. In one embodiment, the I/O module may utilize general purpose I/O (GPIO) ports, analog inputs/ outputs, digital inputs/outputs, and the like.

[0058] Referring primarily to FIG. 3, one or more operator controls 174, 176 may additionally be in data communication with the controller 170. The operator controls 174, 176 can include, for example, levers, switches, dials, buttons, or any other appropriate controls, whether now existing or later developed. In some embodiments, at least one of the operator controls 174, 176 is not in direct physical communication with the controller 170, and instead communicates with the controller 170 wirelessly, such as through one or more of near-field (e.g. Bluetooth, Bluetooth Low Energy, LoRA, Near Field Communication (“NFC”), Wi-Fi, Wi-Max, etc ), radio (e.g. RF), or cellular communication technology (e.g. 3G, 4G, 5G, LTE, etc.). This also applies to any other devices that are connected for communication with the controller 170. The chipper 100 may be provided with multiple chipper settings through operator controls, thus providing divergent cutting and/or feeding parameters optimized for different infeed materials. Alternatively, the chipper 100 may operate on the full gamut of infeed materials on a single chipper setting. In some constructions, the chipper 100 may only have a single chipper setting. However, the chipper 100 is configured to provide an infeed control via the controller 170 that is dynamic and automatic in responding and adapting to different materials fed into the chipper 100.

[0059] The infeed control logic may be similar to that disclosed in U.S. Patent Application Publication No. 2021/0229108, or U.S. Patent No. 7,011,258, the entire contents of both of which are incorporated by reference herein, or any other system known in the art or later developed. These systems may utilize trip points for controlling the rotation of the infeed rollers based on prime mover speed and/or cutting mechanism speed. Although it is possible to size the hybrid system 127 so as to enable the cutting mechanism 124 to perform material reduction with continuous infeed of the most demanding material acceptable by the infeed portion 130, this is generally impractical and/or unreasonable due to the wide range of variability in material (e.g., even limited to wood, there may be drastic differences in size, species having different hardness, moisture content, etc.) as this would lead to a gross oversizing of the hybrid system 127 and drive components for most work operations. Thus, while less demanding material may be fed continuously to the cutting mechanism 124 during chipping, the infeed portion 130 is configured to perform cyclic intermittent material feeding for other more demanding material. That is, the infeed portion 130 will feed the material to the cutting mechanism 124, then stop (stopping the forward feeding, optionally also reversing), then feed again, and so on until the material is completely fed into the cutting mechanism 124 and processed thereby. The length of the cutting cycles will vary as forward feeding by the infeed portion 130 is stopped in accordance with a stop threshold of a monitored variable cutting load parameter. In some examples, the individual cutting cycles may average approximately 2-3 seconds. This type of cyclic feed control allows a smaller- sized hybrid system 127 to be used in producing consistent size chips from more difficult material by operating in a plurality of intermittent cycles or bursts so as to keep the operating speed of the cutting mechanism 124 within a prescribed speed range. Satisfactory continuous cutting of the more difficult material 10 may otherwise be impossible due to overloading the hybrid system 127 and/or drive components, which would lead to stalling, or a dragging down of the cutting mechanism 124 out of its prescribed speed range, for example, along with other possible consequences such as inefficient operation and even component damage under certain circumstances. The above-described infeed control logic may be compatible with a wide variety of different power system configurations that provide the prime mover for the cutting mechanism 124 - whether engine only, electric only, or hybrid.

[0060] As will be appreciated by those in the art, the brush chipper 100 and variations thereof are distinguished from continuous-run material reduction machines, such as horizontal grinders and the like, which may be designed to operate at or near 100 percent duty cycle and have a continuous, non-stop stream of input material supply. Such continuous-run machines can in some cases be electrically driven, but not on self-contained battery supply. The expected duty cycle of the hybrid brush chipper 100 can be approximately 20 percent in some constructions, meaning that only about 20 percent of the time the cutting mechanism and feed roller can be operating at full power. This duty cycle is relative to a short portion of the day, for example, it can be continuously chipping at full power for 20 percent of a 10 minute period, or 20 percent of a 30 minute period, or about 20 percent of a 60 minute period. The on-board battery system 123 may be sized such that the theoretical maximum is 20 percent of continuous chipping during a 150 minute period (i.e., 30 minutes of max. power chipping depletes the battery system 123 from full charge). Normal interruption of cutting, along with regeneration of the battery system 123 renders the chipper 100 suitable for a typical work day, without requiring plug-in charging of the battery system 123. As noted above, the chipper 100 is designed for intermittent feeding rather than continuous feeding, and it would be practically impossible for an operator to continuously feed material to this type of brush chipper to achieve continuous maximum power chipping for long periods of time.

[0061] In one non-limiting example, the controller 170 limits the current output of the battery system 123 to 522 amps, which is the rated limit by the battery manufacturer. The battery system 123 has a rated charge capacity of 261 amp hours (theoretically the battery can run at 261 amps for an hour before recharge). There may be a safety factor included in the current limitations, however, the following sentences include some example values. The recharge current of the battery is 130 amps (which is related to a predicted estimation of the duty cycle, approximately 130 amps x 4 « 522, so 20 percent operating time, 80 percent recharge time). Theoretically, the chipper could operate for half an hour without charging (261 amp hours / 522 amp output). However, not all chipping will require maximum amperage, so the duty cycle may be higher for lighter load conditions and may vary drastically depending on the characteristics of the infeed material. To fully charge the battery system 123, it may be advisable for the customer to plug-in the machine 100 for charging between work shifts/days, however, it is not necessarily required to ensure operability. For charging, the chipper 100 can be plugged into a common 120 volt, 15 amp outlet.

[0062] The current to the chipping mechanism drive motor 126 may be artificially limited by the control system 175 with respect to its maximum capability, for example in order to reserve current for operating the electric feed roller motor 140 driving the feed roller 132. In one example, the current to the chipping mechanism drive motor 126 is limited to 472 amps to reserve 50 amps of current for the feed roller motor 140 (472 amps + 50 amps = 522 max. amps).

[0063] The control system 175 is powered by the engine alternator. The engine 125 also has a separate battery (not shown) that is charged by the alternator of the engine 125. The control system 175 and engine operates on a 12-volt system. However, in alternative configurations, the control system 175 can be powered by the battery system 123. In this circumstance, the additional power consumption is also factored into the battery usage, but the current draw is minimal compared to the motors 126, 140 for chipping and infeed.

[0064] Economy Mode Battery Charging

[0065] The battery system 123 can be charged at a slower rate when the engine 125 operates at a rate less than the high idle speed (e.g., less than 3600 rpm according to the prior example) during economy mode. The batteries can charge at any amperage above 0. However, in the configuration described earlier (where the engine 125 includes a centrifugal clutch), the recharging speed would be limited to above 1500-2000 rpm due to the centrifugal clutch on the engine (the clutch would disengage below these speeds, therefore not providing power to charge the battery system 123). In configurations where no engine clutch is used, or an alternative clutch is used (such as an electric clutch), the engine 125 can power the drive motor 126 to charge the batteries down to its lowest idle speed.

[0066] The battery system 123 and the electric drive motor 126 may also allow for a boost mode where the chipper 100 (specifically the cutting mechanism 124) is capable of higher performance for a short period of time. The maximum allowable battery discharge level increases substantially (e.g., at least 10 percent, at least 20 percent, or at least 25 percent) for this limited period of boost time (e.g., 600 amp boost current, compared to 472 amp is 27 percent increase). The allowable boost time can be set by the manufacturer and may be limited to 5 seconds, 10 seconds, or 20 seconds. Considerations are made to optimize power output versus fuel consumption in relation to the amount of current recharging the battery system 123.

[0067] The brush chipper 100 has a coolant heater for the battery system 123. The coolant heater may be powered by an external power source, such as the 120 volt plug (same plug as overnight charging) for keeping the battery system 123 warm in cold weather. This is necessary in some configurations where the battery will not charge below 2 degrees Celsius, although it may still discharge below this temperature. During operation, heat created during discharge, such as active chipping, may keep the battery warm enough to recharge during operation on cold days. In some constructions, the coolant heater can be powered by the battery system 123.

[0068] Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described.

Claims

CLAIMS What is claimed is:

1. A material reduction machine comprising: a cutting mechanism; a cutting drive system coupled to drive rotation of the cutting mechanism, the cutting drive system including an electric motor; an infeed portion operable to engage a piece of material to be comminuted by the cutting mechanism and to feed the piece of material to the cutting mechanism; an all-electric infeed drive system coupled to drive rotation of a feed roller of the infeed portion; a sensor operable to sense a variable load parameter indicative of load imparted by feeding the piece of material to the cutting mechanism; and a controller coupled to the sensor and configured to receive a signal representing the sensed load parameter, the controller being operatively coupled to the all-electric infeed drive system to adjustably control the feed of the piece of material to the cutting mechanism in response to the signal.

2. The material reduction machine of claim 1, wherein the all-electric infeed drive system includes an electric motor having an output coupled to the feed roller through a planetary gearbox.

3. The material reduction machine of claim 2, wherein an output shaft of the electric motor of the infeed drive system and an output shaft of the planetary gearbox are arranged coaxial with a rotation axis of the feed roller.

4. The material reduction machine of claim 1, wherein the cutting drive system further includes an internal combustion engine configured to drive the cutting mechanism in parallel with the electric motor of the cutting drive system.

5. The material reduction machine of claim 1, wherein the cutting drive system is provided solely by the electric motor.

6. The material reduction machine of claim 1 , wherein the controller is configured to adjust a feed speed of the feed roller based on the signal.

7. The material reduction machine of claim 1, wherein the controller is configured to control stopping and starting of the feed roller to define a plurality of sequential cutting cycles on the piece of material.

8. The material reduction machine of claim 1, wherein the infeed drive system is powered by an on-board electric power storage unit.

9. The material reduction machine of claim 1, wherein the controller is configured to operate the infeed drive system to rotate the feed roller in a mode where the cutting drive system is unpowered.

10. The material reduction machine of claim 9, wherein the controller is configured to shut off an internal combustion engine of the cutting drive system in the mode.

11. The material reduction machine of claim 1, wherein the controller is configured to enact an economy mode in which the cutting drive system is reduced to a minimum speed in response to the material reduction machine detecting the absence of infeed material.

12. The material reduction machine of claim 11, wherein the controller is configured to continue operating the infeed drive system to rotate the feed roller in the economy mode.

13. The material reduction machine of claim 12, wherein the controller is configured to exit the economy mode in response to an increased current draw of the infeed drive system.

14. The material reduction machine of claim 11, wherein the controller is configured to shut off an internal combustion engine of the cutting drive system in the economy mode.

15. The material reduction machine of claim 1, wherein the electric motor of the cutting drive system is configured by the controller to operate in a regenerative mode to brake rotation of the cutting mechanism.

16. The material reduction machine of claim 1 , wherein the controller is configured to operate the electric motor of the cutting drive system at a maximum allowable current within a slip threshold of a belt drive system between the electric motor and the cutting mechanism during a start-up mode.

17. The material reduction machine of claim 1, wherein the controller is configured to selectively provide a boost mode in which a maximum allowable current draw by the electric motor of the cutting drive system is momentarily increased for a prescribed limited time.

18. The material reduction machine of claim 1, wherein the sensor is operable to sense load on the cutting mechanism.

19. The material reduction machine of claim 1, wherein the sensor is operable to sense load on the infeed drive system that drives rotation of the feed roller.

20. A material reduction machine comprising: an electric power source; a cutting mechanism operable to comminute input material; a controller; and an infeed system configured to supply the input material in a cyclic intermittent manner to the cutting mechanism, the infeed system comprising: a feed roller rotated by an electric motor, the electric motor powered by the electric power source and controlled by the controller, and a gearbox between an output of the electric motor and the feed roller.

21. The material reduction machine of claim 20, further comprising a prime mover system controlled by the controller and operably connected to drive the cutting mechanism, wherein the prime mover system includes one or both of an internal combustion engine and an electric motor.

22. The material reduction machine of claim 21, wherein the prime mover system is a hybrid system configured to drive the cutting mechanism from both an internal combustion engine and an electric motor in parallel.

23. The material reduction machine of claim 22, wherein the internal combustion engine is connected to the cutting mechanism through a centrifugal clutch, and wherein the electric motor of the prime mover system is connected to the cutting mechanism without any clutch.

24. The material reduction machine of claim 20, wherein the gearbox is a planetary gearbox, and wherein the electric motor and the planetary gearbox have respective output shafts arranged coaxial with a rotation axis of the feed roller.

25. The material reduction machine of claim 20, wherein the controller is configured to drive rotation of the feed roller in a mode where the cutting mechanism is unpowered.

26. The material reduction machine of claim 20, wherein the electric power source is an onboard battery system, and the controller is configured to limit current draw available to the cutting mechanism in relation to current required to run the electric motor of the infeed system.