CN219754046U - Vibration leveling machine - Google Patents

Abstract

A vibratory screed includes a screed member, a motor, and an exciter assembly configured to vibrate the screed member in response to receiving torque from the motor via a drive shaft. The exciter assembly includes: a first eccentric mass fixed on the drive shaft; and a second eccentric mass axially and rotationally movable along the drive shaft between a first position and a second position, the second eccentric mass being axially closer to the first eccentric mass than the first position. The vibratory screed further includes a mode selection member for switching the exciter assembly between a first low vibration mode in which the second eccentric mass is in the first position and a second high vibration mode in which the second eccentric mass is in the second position.

Description

Vibration leveling machine

Cross Reference to Related Applications

The present application claims priority from co-pending U.S. provisional patent application No. 63/166,617 filed 3/26 of 2021 and co-pending U.S. provisional patent application No. 63/064,089 filed 8/11 of 2020, the entire contents of both provisional patent applications being incorporated herein by reference.

Technical Field

The present utility model relates to screeds for leveling concrete, and more particularly to vibratory screeds.

Background

The vibratory screed includes a blade and a vibratory mechanism that applies vibrations to the blade to assist in screeding and leveling a poured viscous material, such as concrete.

Disclosure of Invention

The present utility model provides, in one aspect, a vibratory screed comprising a screed member, a motor, and an exciter assembly configured to vibrate the screed member in response to receiving torque from the motor via a drive shaft. The exciter assembly includes: a first eccentric mass fixed on the drive shaft; and a second eccentric mass axially and rotationally movable along the drive shaft between a first position and a second position, the second eccentric mass being axially closer to the first eccentric mass than the first position. The vibratory screed further includes a mode selection member for switching the exciter assembly between a first low vibration mode in which the second eccentric mass is in the first position and a second high vibration mode in which the second eccentric mass is in the second position.

The present utility model provides, in another aspect, a vibratory screed comprising a screed member, a motor, and an exciter assembly configured to vibrate the screed member in response to receiving torque from the motor via a drive shaft. The exciter assembly includes: a first eccentric mass fixed on the drive shaft; and a second eccentric mass axially and rotationally movable along the drive shaft between a first position and a second position. In the first position, the second eccentric mass is 180 degrees around the drive shaft relative to the first eccentric mass. In the second position, the second eccentric mass is axially closer to the first eccentric mass than in the first position and less than 180 degrees about the drive shaft relative to the first eccentric mass. The vibratory screed further includes a mode selection member for switching the exciter assembly between a first low vibration mode and a second high vibration mode. In the first low vibration mode, the second eccentric mass is in the first position. In the second high vibration mode, the second eccentric mass is in a second position.

The present utility model provides, in another aspect, a vibratory screed comprising a screed member, a motor, and an exciter assembly configured to vibrate the screed member in response to receiving torque from the motor via a drive shaft. The exciter assembly includes a first eccentric mass, a second eccentric mass, and a third eccentric mass. The first eccentric mass is fixed on the drive shaft, the second eccentric mass is axially movable along the drive shaft and rotatable relative to the drive shaft, the second eccentric mass has an eccentric weight portion, and the third eccentric mass is axially movable along the drive shaft and rotatable relative to the drive shaft, the third eccentric mass has an eccentric weight portion. The vibratory screed further includes a mode selection member for switching the exciter assembly between a first low vibration mode, a second medium vibration mode, and a third high vibration mode. In the first low vibration mode, the second eccentric mass rotates in cooperation with the first eccentric mass on the drive shaft such that the eccentrically weighted portion of the second eccentric mass is 180 degrees around the drive shaft relative to the first eccentric mass, and the third eccentric mass is axially spaced from the first eccentric mass and is not rotatable with the first eccentric mass. In the second medium vibration mode, both the second eccentric mass and the third eccentric mass are axially spaced apart from the first eccentric mass and cannot rotate with the first eccentric mass. In a third high vibration mode, the third eccentric mass rotates in cooperation with the first eccentric mass on the drive shaft such that the eccentric weighted portion of the third eccentric mass is rotationally aligned with the first eccentric mass on the drive shaft and the second eccentric mass is axially spaced from and unable to rotate with the first eccentric mass.

The present utility model provides in another aspect a vibratory screed comprising: a leveling member; a motor; an exciter assembly configured to vibrate the screed member in response to receiving torque from the motor via the drive shaft; a frame coupled to the screed via a first plurality of vibration dampers configured to attenuate a transmission of vibrations from the screed member to the frame; and a housing in which the control electronics for the motor are located, the housing coupled to the frame via a second plurality of vibration dampers configured to dampen vibration transmission from the frame to the housing.

The present utility model provides in another aspect a vibratory screed comprising: a leveling member; a brushless DC motor; a power switching network coupled between the power source and the brushless dc motor; an exciter assembly configured to vibrate the screed member in response to receiving torque from the motor via the drive shaft; an electrical processor. The electrical processor is electrically coupled to the motor and the power switching network and is configured to: causing the brushless DC motor to operate at a selected speed by providing a pulse width modulated signal to the power switching network, the pulse width modulated signal having a duty cycle; determining a current speed of the brushless DC motor; determining whether a difference between the selected speed and the current speed is above a threshold amount; when the difference between the selected speed and the current speed is above the threshold amount, the duty cycle is modified by a predetermined amount to cause the motor to continue to operate at the selected speed.

Drawings

FIG. 1 is a schematic view of a vibratory screed.

FIG. 2 is a perspective view of an exciter assembly for use with the vibratory screed of FIG. 1, with the second eccentric mass in a first position.

Fig. 3 is an exploded view of the actuator assembly of fig. 2.

Fig. 4 is a perspective view of the exciter assembly of fig. 2 with the second eccentric mass in a second position.

FIG. 5 is a perspective view of another exciter assembly for use with the vibratory screed of FIG. 1, wherein the exciter assembly is in a second intermediate vibration mode.

Fig. 6 is a perspective view of the actuator assembly of fig. 5, wherein the actuator assembly is in a first low vibration mode.

Fig. 7 is a perspective view of the exciter assembly of fig. 5, wherein the exciter assembly is in a third high vibration mode.

Fig. 8 is a perspective view of a first side of a first eccentric mass of the exciter assembly of fig. 5.

Fig. 9 is a perspective view of a second side of the first eccentric mass of the exciter assembly of fig. 5.

Fig. 10 is a perspective view of a vibratory screed according to another embodiment.

Fig. 10A is a side view of the vibratory screed of fig. 10.

FIG. 11 is a cross-sectional view of the vibratory screed taken along line 11-11 of FIG. 10.

FIG. 12 is an enlarged cross-sectional view of the vibratory screed taken along line 12-12 of FIG. 11.

FIG. 12A is a cross-sectional view of the vibratory screed taken along line 12A-12A of FIG. 10A.

Fig. 13 is a simplified block diagram of the vibratory screed of fig. 10.

Before any embodiments of the utility model are explained in detail, it is to be understood that the utility model 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 utility model 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.

Detailed Description

As shown in FIG. 1, the vibratory screed 10 includes a screed member 14 (such as a rod or a screed) for screeding and leveling a viscous material (such as concrete). The vibratory screed 10 further includes an electric motor 18, a battery pack 22 (i.e., a power source) that powers the motor 18, and a frame 26 that supports the motor 18 and the battery pack 22. The frame 26 includes a pair of handles 30, a first platform 34 with a motor 18 and a drive housing 38 disposed therein, and a second platform 38 with the screed member 14 disposed thereunder. In some constructions, the battery pack 22 and motor 18 may be configured as an 80 volt high power battery pack and motor, such as that disclosed in U.S. patent application Ser. No. 16/025,491 (now U.S. patent application publication No. 2019/0006980), filed on 7-month 2, the entire contents of which are incorporated herein by reference. In such a battery pack 22, the battery cells within the battery pack 22 have a nominal voltage of up to about 80V. In some embodiments, the battery pack 22 has a weight of up to about 6 pounds (lb). In some embodiments, each of the battery cells has a diameter up to 21mm and a length up to about 71 mm. In some embodiments, the battery pack 22 includes up to twenty cells. In some embodiments, the battery cells are connected in series. In some embodiments, the battery cell is operable to output a sustained operation discharge current between about 40A and about 60A. In some embodiments, each of the battery cells has a capacity between about 3.0Ah and about 5.0 Ah. Also, in some embodiments of the motor 18, when used with an 80 volt battery pack 22, the motor 18 is a high power output motor having a power output of at least about 2760W and a nominal outer diameter (measured at the stator) up to about 80 mm. In alternative embodiments, the battery pack 22 may power the motor 18 with a power output different from (i.e., less than or greater than) 2760W. In alternative embodiments, a gas engine may be used in place of the electric motor and battery.

With continued reference to fig. 1, in order to dampen vibrations transmitted to the operator, motor 18, and battery pack 22, a vibration damper 42 is disposed between first platform 34 and second platform 38, and between first platform 34 and handle 30. Another vibration damper 46 is arranged between the drive housing 38 and the first platform 34 and the drive housing 38. The flexible drive shaft 50 transfers torque from the motor 18 to an exciter assembly 54 configured to vibrate the screed member 14. The exciter assembly 54 includes an eccentric mass 58 coupled for rotation with the drive shaft 50 and disposed in an exciter housing 62 coupled to the screed member 14. In response to the motor 18 rotating the drive shaft 50, the eccentric mass 58 rotates about a rotational axis 66 defined by the drive shaft 50, causing a rotational imbalance that transmits vibrations to the screed member 14 through the exciter housing 62, thereby causing the screed member 14 to vibrate in a direction parallel to the axis 66.

Instead of the exciter assembly 54, as shown in fig. 2-4, an embodiment of an exciter assembly 68 is shown that may be used with the vibratory screed 10 and disposed within the exciter housing 62. The exciter assembly 68 includes a first eccentric mass 70 secured to the drive shaft 50 and a second eccentric mass 74 movable along the drive shaft 50, as described in further detail below. A spring 78 is disposed on the drive shaft 50 and is disposed on the first eccentric mass 70 to bias the second eccentric mass 74 away from the first eccentric mass 70. The drive shaft 50 includes an outer helical groove 82 and the second eccentric mass 74 includes an inner helical groove 86 with a ball 90 disposed within and between the outer helical groove 82 and the inner helical groove 86. On the opposite side of the second eccentric mass 74 from the first eccentric mass 70, a conversion collar 94 is arranged on the drive shaft 50 adjacent to the second eccentric mass 74. The first bearing 98 rotatably supports the drive shaft 50 below the first eccentric mass 74 and the second bearing 102 rotatably supports the drive shaft 50 above the shift collar 94.

In operation of the actuator assembly 68 of fig. 2-4, the actuator assembly 68 is in its default state in the first low vibration mode shown in fig. 2. In the low vibration mode of the exciter assembly 68, the spring 78 biases the second eccentric mass 74 upwardly against the shift collar 94 to a first position in which the second eccentric mass 74 is oriented 180 degrees about the drive shaft 50 relative to the first eccentric mass 70. Specifically, the angular position of the second eccentric mass 74 about the drive shaft 50 is determined by the position of the ball 90 in the inner helical groove 86. When the motor 18 is activated and the exciter assembly 68 is in the first low vibration mode, the first and second eccentric masses 70, 74 rotate with the drive shaft 50, thereby producing vibrations that are transmitted through the exciter housing 62 to the screed member 14. However, since the first and second eccentric masses 70, 74 are 180 degrees from each other about the drive shaft 50, the first and second eccentric masses 70, 74 act as counterweights to each other, thereby reducing the rotational imbalance of the drive shaft 50 and thus reducing the amplitude of the vibrations generated by the exciter assembly 68.

If the operator desires to increase the amplitude of the vibrations transmitted to the screed member 14, the operator manipulates a mode selector 100, such as a knob or sliding actuator, located outside of the exciter housing 62. The mode selector 100 is operatively coupled to the shift collar 94 via shift pins 104 disposed between parallel flanges 105 of the shift collar 94. Manipulation of the mode selector 100 causes the shift collar 94 and thus the second eccentric mass 74 to move along the drive shaft 50 toward the first eccentric mass 70 to a second position (fig. 4), corresponding to a second high vibration mode of the exciter assembly 68. As the second eccentric mass 74 moves toward the drive shaft 50, the second eccentric mass 74 also rotates about the drive shaft 50 because the angular position of the second eccentric mass is determined by the position of the ball 90 in the inner helical groove 86. Then, when the motor 18 is activated, the rotational imbalance of the drive shaft 50 increases as the second eccentric mass 74 is closer to being in rotational alignment, or substantially rotational alignment, with the first eccentric mass 70 on the drive shaft 50, thereby increasing the amplitude of the vibrations generated by the exciter assembly 68 relative to the first low vibration mode of the exciter assembly 68.

If the operator thereafter wishes to adjust the actuator assembly 68 back to the first low vibration mode, the operator manipulates the mode selector 100 to move the shift collar 94 away from the first eccentric mass 70, thus allowing the spring 78 to bias the second eccentric mass 74 back to the first position shown in FIG. 2 corresponding to the first low vibration mode of the actuator assembly 68. In some embodiments, the shift collar 94 is movable by the mode selector 100 when the motor 18 is activated, while in other embodiments, the shift collar 94 is movable only prior to operation and then locked in place prior to activation of the motor 18.

In lieu of the exciter assembly 54 or the exciter assembly 68, as shown in fig. 5-7, another embodiment of an exciter assembly 106 is shown for use with the vibratory screed 10 and disposed within the exciter housing 62. The exciter assembly 106 includes a first eccentric mass 110 secured to the drive shaft 50, a second eccentric mass 114 that is neither axially nor rotationally fixed to the drive shaft 50, and a third eccentric mass 118 that is likewise neither axially nor rotationally fixed relative to the drive shaft 50, as described in further detail below. A first spring 122 is disposed on the drive shaft 50 and is disposed on a first thrust collar 126 to bias the second eccentric mass 114 toward the first eccentric mass 110. A second spring 130 is disposed on the drive shaft 50 and is disposed on the second thrust collar 134 to bias the third eccentric mass 118 toward the first eccentric mass 110.

The second eccentric mass 114 includes an eccentric weight portion 138 and the third eccentric mass 118 also includes an eccentric weight portion 142. The mode selector (e.g., knob 146) external to the actuator housing 62 includes a first arm 148 and a second arm 150 that are engageable with the second eccentric mass 114 and the third eccentric mass 118, respectively or simultaneously, as explained in further detail below.

As shown in fig. 5 and 8, the second eccentric mass 114 includes a clutch member 154 configured to be received in a first recess 156 on a first face 158 of the first eccentric mass 110 in facing relationship with the second eccentric mass 114. The first recess 156 is rotationally positioned on the first face 158 and the clutch member 154 is rotationally positioned on the second eccentric mass 114 such that when the clutch member 154 is received in the first recess 156, the second eccentric mass 114 is locked to rotate with the first eccentric mass 110 with the drive shaft 50 and the eccentric weighted portion 138 of the second eccentric mass 114 is disposed 180 degrees about the drive shaft 50 relative to the first eccentric mass 110.

As shown in fig. 5 and 9, the third eccentric mass 118 includes a clutch member 162 configured to be received in a second recess 166 on a second face 170 of the first eccentric mass 110, the second face being in facing relationship with the third eccentric mass 118. The second face 170 of the first eccentric mass 110 is opposite the first face 158. The second recess 166 is rotationally positioned on the second face 170 and the clutch member 162 is rotationally positioned on the third eccentric mass 118 such that when the clutch member 162 is received in the second recess 166, the third eccentric mass 118 is locked to rotate with the first eccentric mass 110 with the drive shaft 50 and the eccentric weight portion 142 of the third eccentric mass 118 is rotationally aligned with the first eccentric mass 110 on the drive shaft 50.

In operation of the actuator assembly 106 of fig. 5-7, the knob 146 is movable to a first position (fig. 6) in which the knob 146 is rotated such that both the first arm 148 and the second arm 150 engage only the third eccentric mass 118, thereby placing the actuator assembly 106 in the first low vibration mode. Since neither the first arm 148 nor the second arm 150 blocks the second eccentric mass 114, the second eccentric mass is biased towards the first eccentric mass 110 by the first spring 122 such that when the clutch member 154 is received in the first recess 156, the second eccentric mass 114 is locked to rotate with the first eccentric mass 110 with the drive shaft 50 and the eccentric weighted portion 138 of the second eccentric mass 114 is disposed 180 degrees around the drive shaft 50 relative to the first eccentric mass 110, as shown in fig. 6. Thus, when the exciter assembly 106 is operating in the first low vibration mode, since the second eccentric mass 114 is locked to rotate with the first eccentric mass 110 on the drive shaft 50, and since the eccentric weight portion of the second eccentric mass 114 is rotationally offset 180 degrees relative to the first eccentric mass 110, the first eccentric mass 110 and the second eccentric mass 114 act as counterweights to each other as they rotate together about the drive shaft 50, thus reducing the rotational imbalance of the drive shaft 50 and thus reducing the vibration amplitude of the exciter assembly 106. When the first eccentric mass 110 and the second eccentric mass 114 are rotated together, the third eccentric mass 118 does not rotate with the drive shaft 50 because the arms 148, 150 block the third eccentric mass from mating with the first eccentric mass 110. Thus, the third eccentric mass 118 remains stationary while the drive shaft 50 and the first and second eccentric masses 110, 114 co-rotate.

If the operator desires to increase the vibration of the actuator assembly 106, the knob 146 may be moved to a second position (FIG. 5) in which the knob 146 is rotated such that the first arm 148 engages the second eccentric mass 114 and the second arm 150 engages the third eccentric mass 118, thereby placing the actuator assembly 106 in a second medium vibration mode. In the second medium vibration mode, the first and second arms 148, 150 block the second and third eccentric masses 114, 118 from axially engaging the first eccentric mass 110, respectively, such that neither the first and second eccentric masses 114, 118 are engaged to rotate with the first eccentric mass 110 or the drive shaft 50. Thus, when the exciter assembly 106 is operating in the second medium vibration mode, neither the second eccentric mass 114 nor the third eccentric mass 118 can act as a counterweight to each other (as in the first low vibration mode) because the first eccentric mass 110 is not in rotational engagement with the second eccentric mass 114. As such, the rotational imbalance of the drive shaft 50 and the vibration amplitude of the exciter assembly 106 are increased relative to the first low vibration mode.

If the operator desires to further increase the vibration of the actuator assembly 106, the knob 146 may be moved to a third position (FIG. 7) in which the knob 146 is rotated such that both the first arm 148 and the second arm 150 engage only the second eccentric mass 114, thereby placing the actuator assembly 106 in a third high vibration mode. Since neither the first arm 148 nor the second arm 150 blocks the third eccentric mass 118, the third eccentric mass 118 is biased toward the first eccentric mass 110 by the second spring 130 such that when the clutch member 162 is received in the second recess 166, the third eccentric mass 118 is locked for rotation with the first eccentric mass 110 on the drive shaft 50 and the eccentric weighted portion 142 of the third eccentric mass 118 is rotationally aligned with the first eccentric mass 110 on the drive shaft 50, as shown in fig. 6. Thus, when the exciter assembly 106 is operating in the third high vibration mode, the imbalance on the drive shaft 50 increases as the third eccentric mass 118 is locked for rotation with the first eccentric mass 110 on the drive shaft 50, and as the eccentric weighted portion 142 of the third eccentric mass 118 is rotationally aligned with the first eccentric mass 110, as compared to when the third eccentric mass 118 is spaced from and unable to rotate with the first eccentric mass 110. Accordingly, the rotational imbalance of the drive shaft 50 and the vibration amplitude of the exciter assembly 106 are increased relative to the first mode and the second mode. When the first eccentric mass 110 and the third eccentric mass 118 are rotated together, the second eccentric mass 114 does not rotate with the drive shaft 50 because the arms 148, 150 block the second eccentric mass from mating with the first eccentric mass 110. Thus, the second eccentric mass 114 remains stationary while the drive shaft 50 and masses 110, 118 rotate together.

Typical vibratory screeds limit or do not give the operator the ability to adjust the amplitude of the vibrations transmitted to the screed member 14 independently of the speed of the adjustment motor 18 (and thus the frequency of the vibrations, rather than the amplitude of the vibrations). Even though an operator may change the amplitude of vibration of a typical vibratory screed, such amplitude changes involve manually removing nuts or bolts from the drive shaft to adjust the position of the eccentric mass to a desired position, which is time consuming and difficult and may undesirably expose the exciter assembly to the concrete.

In contrast to typical vibratory screeds, both of the exciter assemblies 68, 106 are disposed in the sealed exciter housing 62, and varying the amplitude of vibration transmitted to the screed member 14 is as simple as adjusting the mode selection member 146. This allows the operator to quickly and efficiently change vibration modes for new casting conditions during screed operation while providing better protection for the exciter assemblies 68, 106, thereby increasing their life.

Fig. 10-12 illustrate a vibratory screed 210 according to another embodiment. The vibratory screed 210 may include features similar to the vibratory screed 10 discussed above. Conversely, the features of the vibratory screed 210 may be adapted for use with the vibratory screed 10 discussed above. As shown in FIG. 10, the vibratory screed 210 includes a screed 214 for screeding and leveling a viscous material, such as concrete. The vibratory screed 210 further includes a brushless DC (BLDC) motor 218 located within the motor housing 220, a battery pack 222 for powering the motor 218, and a housing 226, with control electronics (e.g., one or more of an electronic processor 308, a memory 312, a power switch network 316, and/or a memory 328) associated with the motor 218 located within the housing and the battery pack 222 supported on the housing. The motor 218 includes a rotor 218a and a stator 218b (fig. 11). The screed 210 also includes a pair of handles 230 (fig. 10) extending from the frame 256 that a user holds to maneuver the screed 210 at the construction site.

The motor 218 is configured to drive an actuator assembly 234 that includes an actuator housing 238 (fig. 11). The actuator housing 238 includes a pair of wings 242 (FIG. 10) that extend parallel to the screed 214. Each wing 242 includes a clamp 246 (fig. 11) secured thereto to clamp onto screed 214 and secure screed 214 to exciter housing 238. In some embodiments, the clamp 246 may be configured as a quick release mechanism, including, for example, an eccentric cam latch. As shown in fig. 11, each clamp 246 includes an edge clamp 246a (which is secured to the associated wing 242) and a compatible interface 246b (which is integrally formed with the associated wing 242 of the actuator housing 238). Interface 246b is shaped to be compatible with the various screed 214. The clamp 246 may be another mechanism operable to secure the screed 214 to the wing portion 242.

As shown in fig. 10 and 10A, in order to dampen vibrations transmitted to the operator, the control electronics within the housing 226, and the battery pack 222, a vibration damper 250A (e.g., a viscoelastic bushing or spring damper unit) is disposed between each wing 242 and the frame 256. In addition, a vibration damper 250b (e.g., a viscoelastic bushing or a spring damper unit) is disposed between the frame 256 and the housing 226. In the illustrated embodiment of the vibratory screed 210, four vibration dampers 250a are cylindrical and are disposed in a rectangular array (as viewed from above) between the frame 256 and the exciter housing 238. Also, in the illustrated embodiment of the vibratory screed 210, the four vibration dampers 250b are cylindrical and are disposed in a rectangular array (as viewed in a direction perpendicular to the frame 256) between the frame 256 and the housing 226. The vibration dampers 250a, 250b are also symmetrically positioned with respect to a vertical plane (coplanar with the cross-section 11-11 in fig. 10) bisecting the housing 226 and the motor 218.

As shown in fig. 11, drive shaft 260 receives torque from motor 218 and transmits the torque to actuator shaft 264 of actuator assembly 234 via intermediate shaft 268 and resilient coupling 272. The exciter shaft 264 includes an eccentric mass 276 and is rotatably supported within the exciter housing 238 by a first bearing 280 and a second bearing 284. A motor cover 288 is disposed on the motor housing 220 and covers the drive shaft 260 by extending over the neck 292 of the actuator housing 238. In response to the motor 218 rotating the drive shaft 260, the eccentric mass 276 rotates, causing a rotational imbalance that transmits vibrations through the exciter housing 238 to the screed 214, thereby causing the screed 214 to vibrate in a direction perpendicular to the exciter shaft 264.

As shown in fig. 12, the first bearing 280 is disposed between the neck 292 of the actuator housing 238 and a retaining ring 296 disposed in the actuator housing 238. The second bearing 284 is disposed between the larger diameter portion 300 of the actuator shaft 264 and the lower flange 304 of the actuator housing 238. As shown in fig. 12A, the exciter housing 238 and the motor housing 220 are both fixedly secured to the intermediate housing 305 by a plurality of fasteners 306. At least one fastener 306 secures the actuator housing 238 to the intermediate housing 305. At least one fastener 306 secures motor housing 220 to intermediate housing 305. Also, the actuator housing 238 is rigidly connected to the wing 242, which in turn is rigidly connected to the screed 214 via a clamp 246. As such, vibrations generated by the rotating eccentric mass 276 are transmitted through the exciter housing 238 and wing 242 without attenuation. The resilient coupling 272 is located within the intermediate housing 305. In the illustrated embodiment, the resilient coupling 272 is formed of plastic. The elastic coupling 272 provides collinear isolation (inline isolation) of vibrations generated by the eccentric mass 276 to inhibit damage to the motor 218. The resilient coupling 272 is shown engaging the secondary coupling 273 and the rotor 218a. The secondary coupler 273 engages the resilient coupler 272 and the intermediate shaft 268.

FIG. 13 is a simplified block diagram of a vibratory screed 210 according to an exemplary embodiment. In the illustrated example, the vibratory screed 210 includes an electronic processor 308, a memory 312, a battery pack 222, a power switching network 316 (including field effect transistors or FETs), a rotor position sensor 320, and a trigger 324 (see fig. 10, which illustrates the trigger 324 adjacent to one of the handles 230). In some embodiments, electronic processor 308 is implemented as a microprocessor with a separate memory (e.g., memory 312). In other embodiments, the electronic processor 308 may be implemented as a microcontroller (with the memory 328 on the same chip). In other embodiments, electronic processor 308 may be implemented using multiple processors. Further, the electronic processor 308 may be implemented in part or in whole as, for example, a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), or the like, and accordingly, the memory 312 may not be needed or may be modified. The memory 312 stores instructions that are executed by the electronic processor 308 to perform the functions of the vibratory screed 210 described herein. Memory 312 includes Read Only Memory (ROM), random Access Memory (RAM), other non-transitory computer-readable media, or combinations thereof.

The power switching network 316 enables the electronic processor 308 to control the operation of the motor 218. Typically, when trigger 324 is depressed, current is supplied from battery pack 222 to motor 218 via power switch network 316. When the trigger 324 is not depressed, current is not supplied from the battery pack 222 to the motor 218. In some embodiments, the amount by which the trigger 324 is depressed is related to or corresponds to the desired rotational speed of the motor 218 (i.e., closed loop speed control). In other embodiments, the amount by which the trigger 324 is depressed is related to or corresponds to the desired torque (i.e., open loop speed control, or "direct drive").

In response to the electronic processor 308 receiving the drive request signal from the trigger 324, the electronic processor 308 enables the power switching network 316 to provide power to the motor 218. Through the power switching network 316, the electronic processor 308 controls the amount of current available to the motor 218, thereby controlling the speed and torque output of the motor 218. The power switching network 316 includes a plurality of FETs, for example, a six FET bridge that receives Pulse Width Modulated (PWM) signals from the electronic processor 308.

Rotor position sensor 320 is coupled to electronic processor 308. The rotor position sensor 320 includes, for example, a plurality of hall effect sensors, quadrature encoders, etc., attached to the motor 18. The rotor position sensor 320 outputs motor feedback information to the electronic processor 308, such as an indication (e.g., a pulse) of when the magnet of the rotor of the motor 218 rotates past the surface of the hall sensor. Based on motor feedback information from rotor position sensor 320, electronic processor 308 may determine the position, speed, and acceleration of rotor 218 a. In response to the motor feedback information and the signal from the trigger 324, the electronic processor 308 transmits control signals to control the power switching network 316 to drive the motor 18. For example, by selectively enabling and disabling FETs of the power switching network 316, power received from the battery pack 222 is selectively applied to the stator windings of the motor 218 in a cyclical manner to cause the rotor of the motor 18 to rotate.

In some embodiments, the motor 218 is a sensorless motor that does not include a hall effect sensor. The removal of the hall effect sensor provides the advantage of further reducing the size of the motor package. In these embodiments, rotor position is detected based on detecting current in the inactive phase of motor 218, back electromotive force (EMF), and the like. Specifically, instead of hall sensors, current sensors, voltage sensors, etc. are provided external to the motor 18, for example in the power switching network 316 or on the current path between the power switching network 316 and the motor 218. As the rotor 218a moves past the stator phase coils, the permanent magnets of the rotor 218a generate a back EMF in the inactive phase. The electronic processor 308 detects the back EMF generated in the inactive phase (e.g., using a voltage sensor) or the corresponding current (e.g., using a current sensor) to determine the position of the rotor 218 a. The motor 218 is then similarly commutated as described above based on the positional information of the rotor 218 a. Such sensorless motor 218 may function without a hall sensor acting as a quadrature encoder to output motor speed. Alternatively, as the state of charge of the battery 222 decreases, a constant power control circuit may be used to minimize the impact on speed. Such a sensorless motor 218 may include initializing the rotor pair Ji Licheng, which routine is executed when starting the rotor 218a to determine the position of the rotor 218a prior to commutation.

The electronic processor 308 uses the motor feedback information to ensure proper timing of the control signals to the power switching network 316 and provides closed loop feedback to control the speed of the motor 218 at a desired level (i.e., constant speed). Specifically, the electronic processor 308 increases and decreases the duty cycle of the PWM signal provided to the power switching network 316 to maintain the speed of the motor 218 at the speed selected by the trigger 324. For example, as the load on the motor 218 increases, the speed of the motor 218 may decrease. The electronic processor 308 detects a decrease in speed using the rotor position sensor 320 or the back EMF sensor and increases the duty cycle of the PWM signal provided to the power switching network 316 (and thus the power provided to the motor 218) proportionally to increase the speed back to the selected speed. Similarly, as the load on the motor 218 decreases, the speed of the motor 218 may increase. The electronic processor 308 detects an increase in speed using the rotor position sensor 320 or the back EMF sensor and proportionally reduces the duty cycle of the PWM signal provided to the power switching network 316 (and thus the power provided to the motor 218) to reduce the speed back to the selected speed. Such operation of the electronic processor 308 may be continuous when operating the vibratory screed 210.

In open loop speed control, the electronic processor 308 maintains a constant duty cycle of the PWM signal (and thus, a constant electrical power provided to the motor 218) corresponding to the position of the trigger 324.

The electronic processor 308 is operable to receive the sensed position of the rotor 218a and commutate the electric motor 18 according to the sensed position. Additionally or alternatively, the electronic processor 308 is operable to receive the sensed speed of the rotor 218a and adjust the amount of power provided to the electric motor 218 in the manner described above such that the motor 218 is driven at a desired speed. In the illustrated embodiment, the desired speed is a speed of 9,000 revolutions per minute or more. For example, the desired speed may be 10,000 revolutions per minute. Since the speed of the electric motor 218 is maintained at the desired speed, the vibration frequency of the screed 214 is also maintained.

It may be desirable to maintain the vibration frequency of screed 214 during operation of vibratory screed 210. In advancing the screed along wet concrete, it is important that the screed 214 vibrate at a speed high enough to effect proper concrete consolidation. If the speed of motor 218 drops below a threshold, such as 9,000 revolutions per minute, the concrete may not properly set. In addition, if the speed of the motor 218 rises above a threshold (e.g., 15,000 revolutions per minute), the concrete may not properly set. Thus, if the vibration frequency falls outside the threshold range, the integrity and appearance of the vibrated concrete will be negatively affected.

By sensing the speed of the rotor 218a and reversing the electric motor 218 according to the sensed speed, the motor 218 can avoid any speed differential due to changes in the state of charge of the battery pack 222. As the vibratory screed 210 is used, the state of charge of the battery pack 222 becomes depleted. The electronic processor 308 is operable to receive the sensed speed of the rotor 218a from the rotor position sensor 320 or the back EMF sensor and to operate commutation of the motor 218 independently of the state of charge of the battery pack 222.

By utilizing the electronic processor 308 and rotor position sensor 320 of the BLDC motor 218, the vibratory screed 210 has many other advantages over other known vibratory screeds. The vibratory screed 210 may be capable of operating with greater efficiency than known vibratory screeds. By reversing the motor 218 based on the sensed speed of the rotor 218a, mechanical resistance and friction between the components is eliminated. By reversing the motor 218 based on the sensed rotor 218a position, a constant phase lead can be optimized, making the load of the tool relatively constant. This is not possible with brush DC electric motors. In a brushed DC electric motor, the brushes wear and the phase lead varies with brush geometry. In this manner, since the brushless DC motor 218 phase lead is optimized and does not change throughout use, high efficiency is maintained.

Various features of the utility model are set forth in the appended claims.

Claims (39)

1. A vibratory screed comprising:

a leveling member;

a motor;

an exciter assembly configured to vibrate the screed member in response to receiving torque from the motor via a drive shaft, the exciter assembly comprising

A first eccentric mass fixed to the drive shaft, an

A second eccentric mass axially movable along the drive shaft between a first position and a second position, the second eccentric mass being closer to the first eccentric mass than in the first position; and

a mode selection member for switching the actuator assembly between:

a first low vibration mode in which the second eccentric mass is in the first position, and

a second high vibration mode in which the second eccentric mass is in the second position.

2. The vibratory screed of claim 1, wherein in the first position the second eccentric mass is 180 degrees about the drive shaft relative to the first eccentric mass.

3. The vibratory screed of claim 1, wherein in the second position the second eccentric mass surrounds the drive shaft less than 180 degrees relative to the first eccentric mass.

4. The vibratory screed of claim 1, wherein in the second position the second eccentric mass is rotationally aligned with the first eccentric mass on the drive shaft.

5. The vibratory screed of claim 1, wherein the second eccentric mass is biased toward the first position.

6. The vibratory screed of claim 1, wherein the mode selection member is configured to move the second eccentric mass along the drive shaft toward the first eccentric mass to the second position.

7. The vibratory screed of claim 1, wherein the motor is operable at the same motor speed in both the first low vibration mode and the second high vibration mode such that the amplitude of vibration caused by the exciter assembly is adjusted only by moving the second eccentric mass between the first and second positions, without adjusting the frequency of the vibration.

8. The vibratory screed of claim 1, further comprising

A frame on which the motor is mounted; and

a vibration damper is located between the frame and the exciter assembly.

9. A vibratory screed comprising:

a leveling member;

a motor;

an exciter assembly configured to vibrate the screed member in response to receiving torque from the motor via a drive shaft, the exciter assembly comprising

A first eccentric mass, the first eccentric mass being fixed on the drive shaft,

a second eccentric mass axially and rotationally movable along the drive shaft between:

a first position in which the second eccentric mass is 180 degrees around the drive shaft relative to the first eccentric mass, and

a second position in which the second eccentric mass is axially closer to the first eccentric mass than in the first position and less than 180 degrees about the drive shaft relative to the first eccentric mass; and

a mode selection member for switching the actuator assembly between:

a first low vibration mode in which the second eccentric mass is in the first position, and

A second high vibration mode in which the second eccentric mass is in the second position.

10. The vibratory screed of claim 9, wherein in the second position the second eccentric mass is rotationally aligned with the first eccentric mass on the drive shaft.

11. The vibratory screed of claim 9, wherein the second eccentric mass is biased toward the first position.

12. The vibratory screed of claim 9, wherein the drive shaft comprises an outer helical groove and the second eccentric mass comprises an inner helical groove, and wherein the vibratory screed further comprises a ball disposed within and between the outer helical groove and the inner helical groove.

13. The vibratory screed of claim 9, wherein the mode selection member is configured to move the second eccentric mass along the drive shaft toward the first eccentric mass to the second position.

14. The vibratory screed of claim 13, wherein the mode selection member is movable when the motor is activated.

15. The vibratory screed of claim 13, wherein the mode selection member is movable only prior to operation of the motor, and wherein the second eccentric mass is locked in either the first position or the second position prior to activation of the motor.

16. The vibratory screed of claim 9, wherein the exciter assembly further comprises a shift collar operatively coupled to the mode selection member such that manipulation of the mode selection member causes the second eccentric mass to move along the drive shaft toward the first eccentric mass to the second position.

17. A vibratory screed comprising:

a leveling member;

a motor;

an exciter assembly configured to vibrate the screed member in response to receiving torque from the motor via a drive shaft, the exciter assembly comprising:

a first eccentric mass, the first eccentric mass being fixed on the drive shaft,

a second eccentric mass axially movable along the drive shaft and rotatable relative thereto, the second eccentric mass having an eccentric weight portion, and

a third eccentric mass axially movable along the drive shaft and rotatable relative to the drive shaft, the third eccentric mass having an eccentric weight portion; and

a mode selection member for switching the actuator assembly between:

A first low vibration mode in which the second eccentric mass rotates in cooperation with a first eccentric mass on the drive shaft such that an eccentrically weighted portion of the second eccentric mass is 180 degrees around the drive shaft relative to the first eccentric mass and the third eccentric mass is axially spaced from and unable to rotate with the first eccentric mass,

a second medium vibration mode in which both the second eccentric mass and the third eccentric mass are axially spaced from and unable to rotate with the first eccentric mass, and

a third high vibration mode in which the third eccentric mass rotates in concert with the first eccentric mass on the drive shaft such that an eccentric weighted portion of the third eccentric mass is rotationally aligned with the first eccentric mass on the drive shaft and the second eccentric mass is axially spaced from and unable to rotate with the first eccentric mass.

18. The vibratory screed of claim 17, wherein both the second eccentric mass and the third eccentric mass are biased toward the first eccentric mass.

19. The vibratory screed of claim 17, wherein the mode selection member includes first and second arms that are engageable with the second and third eccentric masses, respectively or simultaneously.

20. The vibratory screed of claim 19, wherein,

in the first low vibration mode, the first and second arms block the third eccentric mass from engaging the first and second eccentric masses,

in the second medium vibration mode, the first arm blocks the second eccentric mass from engaging the first eccentric mass and the second arm blocks the third eccentric mass from engaging the first eccentric mass, and

in the third high vibration mode, the first and second arms block the second eccentric mass from engaging the first and third eccentric masses.

21. A vibratory screed comprising:

a leveling member;

a motor;

an exciter assembly configured to vibrate the screed member in response to receiving torque from the motor via a drive shaft;

a frame coupled to the screed via a first plurality of vibration dampers configured to attenuate transmission of vibrations from the screed member to the frame; and

A housing in which control electronics for the motor are located, the housing coupled to the frame via a second plurality of vibration dampers configured to dampen vibration transmission from the frame to the housing.

22. The vibratory screed of claim 21, further comprising a handle coupled to the frame.

23. The vibratory screed of claim 21, wherein the exciter assembly includes an exciter housing and a clamp configured to clamp onto the screed member and secure the screed member to the exciter housing.

24. The vibratory screed of claim 23, wherein the exciter housing includes a pair of wings extending parallel to the screed member, and wherein the first plurality of vibration dampers is positioned between the frame and each wing.

25. The vibratory screed of claim 21, wherein the first plurality of vibration dampers are viscoelastic bushings.

26. The vibratory screed of claim 21, wherein the second plurality of vibration dampers are viscoelastic bushings.

27. The vibratory screed of claim 21, further comprising a battery pack supported on the housing.

28. The vibratory screed of claim 27, wherein the first and second pluralities of vibration dampers are configured to attenuate vibration transfer from the screed member to the battery pack.

29. The vibratory screed of claim 27, wherein the battery pack comprises a nominal voltage of 80V and is configured to output a sustained operation discharge current between 40A and 60A.

30. The vibratory screed of claim 29, wherein the motor is a brushless DC electric motor having an output power of at least 2760W and a nominal outer diameter of up to 80 mm.

31. A vibratory screed comprising:

a leveling member;

a brushless DC motor;

a power switching network coupled between a power source and the brushless dc motor;

an exciter assembly configured to vibrate the screed member in response to receiving torque from the motor via a drive shaft; and

an electronic processor electrically coupled to the motor and the power switching network and configured to

The brushless dc motor is operated at a selected speed by providing pulse width modulated signals to the power switching network, the pulse width modulated signals having a duty cycle,

Determining a current speed of the brushless dc motor,

determining whether the difference between the selected speed and the current speed is greater than a threshold amount, and

when the difference between the selected speed and the current speed is above the threshold amount, the duty cycle is modified by a predetermined amount to cause the motor to continue operating at the selected speed.

32. The vibratory screed of claim 31, wherein the electronic processor is further configured to

When the current speed is below the selected speed by more than the threshold amount, the duty cycle is increased by the predetermined amount.

33. The vibratory screed of claim 31, wherein the electronic processor is further configured to

The duty cycle is reduced by the predetermined amount when the current speed is greater than the selected speed by more than the threshold amount.

34. The vibratory screed of claim 31, further comprising a rotor position sensor configured to detect a rotor position of the brushless dc motor, wherein the electronic processor is electrically coupled to the rotor position sensor and is further configured to receive a signal from the rotor position sensor indicative of the rotor position, and

The current speed of the motor is determined based on the signals indicative of the rotor position.

35. The vibratory screed of claim 31, wherein the electronic processor is further configured to

The current speed of the brushless DC motor is determined based on back EMF generated in one or more inactive phases of the motor.

36. The vibratory screed of claim 31, further comprising a mode selection member for switching the exciter assembly between a first low vibration mode and a second high vibration mode, wherein the electronic processor is electrically coupled to the mode selection member to receive a selection signal, the electronic processor being further configured to

Setting the selected speed to a first speed when the first low vibration mode is selected using the mode selection member, and

the selected speed is set to a second speed when the second low vibration mode is selected using the mode selection member.

37. The vibratory screed of claim 36, wherein the first speed is greater than 9,000 revolutions per minute and the second speed is less than 15,000 revolutions per minute.

38. The vibratory screed of claim 31, further comprising a frame coupled to the screed via a first plurality of vibration dampers configured to dampen vibration transmission from the screed member to the frame.

39. The vibratory screed of claim 38, further comprising a housing in which the electronic processor is located, the housing coupled to the frame via a second plurality of vibration dampers configured to dampen vibration transmission from the frame to the housing.