US20110158745A1

US20110158745A1 - Vibratory system for a compactor

Info

Publication number: US20110158745A1
Application number: US12/962,758
Authority: US
Inventors: Nicholas A. Oetken; Nathan L. Mashek; John L. Marsolek; Eric A. Hansen
Original assignee: Caterpillar Paving Products Inc
Current assignee: Caterpillar Paving Products Inc
Priority date: 2009-12-31
Filing date: 2010-12-08
Publication date: 2011-06-30
Also published as: CN102182135B; DE102010056531A1; CN102182135A

Abstract

A vibratory system for a compactor is provided. The vibratory system has a first eccentric, a second eccentric, and a drive shaft. The second eccentric is rotatably and coaxially positioned with respect to the first eccentric. The drive shaft is rotatably coupled to the second eccentric and rotatably coupled to the first eccentric through a helical spline.

Description

CLAIM FOR PRIORITY

The present application claims priority from U.S. Provisional Application Ser. No. 61/291,701, filed Dec. 31, 2009, which is fully incorporated herein.

TECHNICAL FIELD

This disclosure relates to a vibratory system for a compactor machine, and more particularly, to a variable amplitude vibratory system for a compactor machine.

BACKGROUND

Vibratory compactor machines are frequently used to compact freshly laid asphalt, soil, and other compactable materials. These compactor machines may include plate type compactors or rotating drum compactors with one or more drums. The drum-type compactor compacts the material over which the machine is driven. In order to compact the material, the drum assembly includes a vibratory mechanism including inner and outer eccentric weights arranged on a rotatable shaft within the interior cavity of the drum, for inducing vibrations on the drum.
The amplitude and frequency of the vibratory forces determine the degree of compaction of the material, and the speed and efficiency of the compaction process. The amplitude of the vibration forces is changed by altering the position of a pair of weights with respect to each other. The frequency of the vibration forces is managed by controlling the speed of a drive motor in the compactor drum.
The required amplitude of the vibration force may vary depending on the characteristics of the material being compacted. For instance, high amplitude works best on thick lifts or soft materials, while low amplitude works best on thin lifts and harsh mixes. Amplitude variation is important because different materials require different levels of compaction. Moreover, a single compacting process may require different amplitude levels because higher amplitude may be required at the beginning of the process, and the amplitude may be gradually lowered as the process is completed.
Conventional vibratory compactor machines are problematic in that the amplitude and frequency of the vibration force can only be set to certain predetermined levels, or the mechanisms for adjusting the vibration amplitude are complex. One such vibratory mechanism is disclosed in U.S. Pat. No. 4,350,460 issued to Lynn A. Schmelzer et al. on Sep. 21, 1982 and assigned to the Hyster Company.
The present disclosure is directed to overcome one or more of the problems as set forth above.

SUMMARY

In one aspect of the present disclosure, a vibratory system for a compactor is provided. The vibratory system has a first eccentric, a second eccentric, and a drive shaft. The second eccentric is rotatably and coaxially positioned with respect to the first eccentric. The drive shaft is rotatably coupled to the second eccentric and rotatably coupled to the first eccentric.
In another aspect of the present disclosure, a compactor is provided. The compactor has a drum and a vibratory system. The drum has a drum axis. The vibratory system is rotatably positioned within the drum about the drum axis and has a first eccentric, a second eccentric, and a drive shaft. The second eccentric is rotatably and coaxially positioned with respect to the first eccentric. The drive shaft is rotatably coupled to the second eccentric and rotatably coupled to the first eccentric.
In a third aspect of the present disclosure, a method of providing a vibratory system for a compactor is provided. The method includes the step of providing a first eccentric, a second eccentric, and a drive shaft. The method also includes the steps of rotatably and coaxially positioning the second eccentric with respect to the first eccentric, and the step of rotatably coupling the drive shaft to the second eccentric. The method includes the step of rotatably coupling the drive shaft to the first eccentric.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a machine embodying the present disclosure;

FIG. 2 shows an axial cross section view taken along the line 2-2 through a compacting drum of the machine of FIG. 1, showing an embodiment of the present disclosure;

FIG. 3 is a detail view of the vibratory mechanism of FIG. 2, with the eccentric shown at the maximum amplitude position; and

FIG. 4 is a detail view of the vibratory mechanism of FIG. 2, with the eccentric shown at the minimum amplitude position.

DETAILED DESCRIPTION

FIG. 1 illustrates a machine 10 for increasing the density of a compactable material or mat 12 such as soil, gravel, or bituminous mixtures. The machine 10 is, for example, a double drum vibratory compactor, having a front or first compacting drum 14 and a rear or second compacting drum 16 rotatably mounted on a main frame 18 about a drum axis 19 (seen in FIG. 2), although compactors having only a single drum may also be used without departing from the present disclosure. The main frame 18 also supports an engine 20 that supplies power to at least one power source 22, 24. Electrical generators or fluid pumps, such as variable displacement fluid pumps, may be used as interchangeable alternatives for power sources 22, 24 without departing from the present disclosure.
As the front drum 14 and the rear drum 16 are structurally and operatively similar, the description, construction and elements comprising the front drum 14 will now be discussed in detail and applies equally to the rear drum 16.
As seen in FIG. 2, the front drum 14 is shown in a split drum configuration. Those skilled in the art will recognize that front drum 14 could also be in a solid drum configuration without departing from the scope and spirit of this disclosure. Notwithstanding, front drum 14 includes a split 15 that separates front drum 14 into a first and a second drum section 30, 32, a first and a second propel motor 42, 44, a pair of offset gearboxes 46, a support arrangement 50, and a vibratory system 90. Each of the first and second drum sections 30, 32 is made up of an outer shell 34 that is manufactured from a steel plate that is rolled and welded at the joining seam. A first bulkhead 36 is fixedly secured to the inside diameter of the outer shell 34 of the first drum section 30 as by welding and a second bulkhead 38 is fixedly secured to the inside diameter of the outer shell 34 of the second drum section 32 in the same manner. The first and second drum sections 30, 32 are vibrationally isolated from the main frame 18 by rubber mounts (not shown).
The first and the second propel motors 42, 44 are positioned between the main frame 18 and the first and the second drum sections 30, 32, respectively. For example, the first and second propel motors 42, 44 are each connected to a mounting plate (not shown) secured to the main frame 18 via rubber mounts (not shown). The output of the first and second propel motors 42, 44 are connected to the first and the second bulkheads 36, 38, respectively, through a pair of offset gearboxes 46. The offset gearboxes 46 allow the first and second propel motors 42, 44 to be positioned offset from the drum axis 19. With a different mounting configuration or motor arrangement, the first and second propel motors may be directly connected to the first and second bulkheads 36, 38, eliminating the offset gearboxes 46. The first and second propel motors 42, 44 are operatively connected to the power source 22, 24, which supplies a pressurized operation fluid or electrical current to the first and second propel motors 42, 44 for propelling the first and second drum section 30, 32.
The support arrangement 50 rotatably connects the first drum section 30 to the second drum section 32 and houses a vibratory mechanism 100 of the vibratory system 90 within a housing 58. The support arrangement 50 is rotatably connected between the first and second bulkheads 36, 38 to enable the first and second drum section 30, 32 to rotate in relation to one another. The support arrangement 50 includes a first support member 52 and a second support member 54. The first support member 52 is connected to the first bulkhead 36, while the second support member 54, being made up of two separate pieces connected by fasteners, is connected to the second bulkhead 38. Although the second support member 54 as shown in this embodiment is made of two separate pieces, it may also be one complete piece. The first support member 52 is rotatably positioned inside the second support member 54 and rotatably connected by a bearing arrangement 56. In this case, the bearing arrangement consists of tapered roller bearings. The support arrangement 50 allows the first propel motor 42 to rotate the first drum section 30 about the drum axis 19 at either the same rate or at a different rate than the second propel motor 44 rotates the second drum section 32 about the drum axis 19.
Of course, this is but one of a number of arrangements that the support arrangement 50 may assume. For example, the second support member 54 may be rotatably positioned outside the first support member 52. The first support member 52 may also be rotatably positioned outside the second support member 54. Another example may have the first and second support members 52, 54 come together at the bearing arrangement 56 where they may be rotatably connected without any overlap of the first and second support members 52, 54. Additionally, the bearing arrangement 56 that may be seen in any of the embodiments may comprise, but is not limited to, tapered roller bearings, ball bearings, and bronze bushings.
The vibratory system 90 includes the vibratory mechanism 100, a vibratory motor 110, a drive shaft 118, and a linear actuator 150. The vibratory mechanism 100 is rotatably supported about the drum axis 19 within the housing 58 with a plurality of bearings 170. The bearings 170 may be cylindrical roller bearings, although other types of bearings or bushings may also be used. In order to provide lubrication and cooling to the vibratory mechanism 100, the housing 58 may be filled with oil. A lip seal 176 may be positioned at the ends of the housing 58 to keep the oil within the housing 58 and dirt and debris out of the housing 58.
Referring now to FIGS. 3-4, the vibratory mechanism 100 is driven by the vibratory motor 110 through the drive shaft 118, and includes an outer eccentric 120, an inner eccentric 130, and a key shaft 140. The vibratory motor 110 may be a hydraulic or electric motor and may be mounted to the machine 10 through a mounting plate (not shown) that is secured to the main frame 18 via rubber mounts (not shown). Alternately, the vibratory motor 110 may be mounted to the main frame through some other way known in the art, such as by mounting the vibratory motor 110 to one of the offset gearboxes 46 through a flange 112. The vibratory motor 110 is rotationally coupled to the drive shaft 118 through an adapter 114 with a speed sensor 116. The speed sensor 116 is a tachometer and may include a toothed ring and pickup, a magnetic sensor, or any other technique known in the art. The vibratory motor 110 may be driven by one of the power sources 22, 24, or by another power source (not shown).
The outer eccentric 120 is shown as a three-piece assembly with a drive side stub shaft 121, a helical side stub shaft 122, and a lobe 126. The drive shaft 118 is attached to the drive side stub shaft 121 via a splined connection or other technique known in the art. The bearings 170 may be attached to the outside of stub shafts 121, 122. The drive side stub shaft 121 and the helical side stub shaft 122 are attached to the lobe 126 via bolts or some other known technique. The lobe 126 may formed as a hollow semi-cylindrical or lobed casting having an axis of rotation and with more weight on one radial side than on the other. The helical side stub shaft 122 also includes a helical bore 124, which will be described in detail below.
The inner eccentric 130 is positioned within the outer eccentric 120 and is rotatably supported about the drum axis 19 with a pair of bearings 172, which may be tapered roller bearings, ball bearings, or bushings such as bronze bushings. Bearings 172 are positioned within the stub shafts 121, 122. The inner eccentric 130 may be a solid semi-cylindrical or lobed casting with more weight on one radial side than on the other. The inner eccentric 130 also includes a bore 132. The bore 132 is formed with one or more splines that extend axially parallel to the drum axis 19. Alternately, the bore 132 may be formed with an axially-extending keyway (not shown).
The key shaft 140 has an axial splined portion 142 at one end, a smooth portion 144 in the middle, and a helical splined portion 146 at the other end. The axial splined portion 142 engages with the bore 132 of the inner eccentric 130 such that the inner eccentric 130 and the key shaft 140 are rotatably fixed with respect to each other. However, the key shaft 140 may still slide axially into the bore 132 of the inner eccentric 130. In one embodiment, the axial splined portion 142 may include 18 straight splined teeth, although other numbers of teeth may be used depending on the application. The helical splined portion 146 engages with the helical bore 124 of the outer eccentric 120 to transfer the linear motion of the key shaft 140 into rotational motion of both the key shaft 140 and inner eccentric 130. The helical splined portion 146 and the helical bore 124 may include helical splines with a spline angle of approximately 60 degrees to slightly less than 90 degrees from the drum axis 19, although any spline angle that permits the linear motion of the key shaft 140 to be transferred to rotational motion of the key shaft 140 may also be used.
The linear actuator 150 has an axially extending rod 152 that engages the key shaft 140. The linear actuator 150 has an extension stroke where the rod 152 extends out from the linear actuator 150, and a retraction stroke where rod 152 retracts into the linear actuator 150. As the rod 152 extends along the drum axis 19, it pushes the key shaft 140 along the drum axis 19. This linear motion is then converted into rotational motion of the key shaft 140 and inner eccentric 130 with the helical spline interface between the helical bore 124 and the helical splined portion 146. The linear actuator 150 may be a hydraulic or electric actuator and may be mounted to the machine 10 through a mounting plate (not shown) that is secured to the main frame 18 via rubber mounts (not shown). Alternately, the linear actuator 150 may be mounted to the main frame 18 through some other way known in the art, such as by mounting the linear actuator 150 to one of the offset gearboxes 46 through a flange 154. The linear actuator 150 may be driven by one of the power sources 22, 24, or by another power source (not shown). The rod 152 may engage the key shaft 140 through an adapter 180. The adapter 180 may be mounted to the key shaft 140 through a bearing 174 and may also include a physical stop such as a set screw or key (not shown) for the outer race of the bearing 174 and/or the rod 152. The physical stop serves to prevent the rod 152 from rotating at the same rate as the key shaft 140, which in turn rotates at the same rate as the vibratory motor 110. The seals of the linear actuator 150 may not be able to handle the high rate of speeds of the vibratory motor 110, which may exceed 3800 revolutions per minute. The linear actuator 150 also includes a position sensor 156, which senses the linear extension of the rod 152 along the drum axis 19.
FIG. 3 shows the vibratory mechanism 100 with the outer eccentric 120 and inner eccentric 130 in phase with each other about the drum axis 19. When the outer and inner eccentrics 120, 130 are in phase and rotated by the vibratory motor 110, the drum 14 produces a maximum amplitude. FIG. 4 shows the vibratory mechanism 100 with the outer eccentric 120 and the inner eccentric 130 180 degrees out of phase with each other about the drum axis 19. When the outer and inner eccentrics 120, 130 are 180 degrees out of phase and rotated by the vibratory motor 110, the drum 14 produces a minimum amplitude.
When the outer and inner eccentrics 120, 130 are 180 degrees out of phase, as seen in FIG. 4, a radial alignment hole 128 in the lobe 126 of the outer eccentric 120 aligns with a similar radial alignment hole 138 in the inner eccentric 130. Due to tolerance stack-up in the manufacture of the vibratory mechanism 100, these alignment holes 128, 138, in combination with a clamp-nut 160, allow the vibratory mechanism 100 to be calibrated. When the outer and inner eccentrics 120, 130 are out of phase with each other, a rod (not shown) may be inserted into both radial alignment holes 128, 138. The clamp-nut 160 is then placed over the key shaft 140, butted up against the helical side stub shaft 122, and locked onto the key shaft 140. If the minimum extension position of rod 152 is used to define the maximum amplitude (as seen in FIG. 3), the clamp-nut 160 provides a physical stop for the extension of rod 152 for the minimum amplitude. Note that the alignment holes 128, 138 may alternately be positioned in the outer and inner eccentrics 120, 130 such that they align when they are in phase, at the maximum amplitude. In such a case, the physical interference of clamp-nut 160 against the helical side stub shaft 122 would indicate the maximum amplitude, and a minimum extension of rod 152 would represent the minimum amplitude.

INDUSTRIAL APPLICABILITY

The disclosed vibratory mechanism and drum for a machine may be used to provide a variably adjustable amplitude ranging from a maximum to a minimum for any compactor machine. In one exemplary embodiment, the vibratory mechanism is for a vibratory compactor, such as a double split drum asphalt compactor.
In operation, as the machine 10 is driven over the compactable material 12, the frequency and amplitude of the vibratory system 90 may be manually controlled by an operator or automatically controlled by an intelligent compaction system. The frequency of impacts may be controlled by increasing or decreasing the speed of the vibratory motor 110, with feedback from the speed sensor 116. The amplitude of the impacts may be controlled by brining the inner eccentric 130 in phase or out of phase with the outer eccentric 120. Starting from a maximum amplitude position as depicted in FIG. 3, the rod 152 of the linear actuator 150 may be extended. As the rod 152 is extended, the key shaft 140, which is rotatably secured to the inner eccentric 130, is pushed along the drum axis 19 into the straight splines of bore 132 of the inner eccentric 130. The helical spline interface between the helical bore 124 and the helical splined portion 146 converts the linear motion of the key shaft 140 and rod 152 into rotational movement of the inner eccentric 130 with respect to the outer eccentric 120. When the inner eccentric 130 and outer eccentric 120 are 180 degrees out of phase with each other, a position of minimum amplitude has been reached, and the clamp-nut 160 provides a physical stop for the further extension of rod 152. Similarly, the amplitude of the vibratory system 90 may be decreased by retracting the rod 152 into the linear actuator 150, moving from the position of FIG. 4 to the position shown in FIG. 3. Intermediate amplitudes less than the maximum or greater than the minimum may be obtained by setting the phase angle of the inner eccentric 130 to the outer eccentric 120 between 0 and 180 degrees. The position sensor 156 may be used to provide feedback to an operator via a display or to the intelligent compaction system.
While the disclosure has been described with reference to details of the illustrated embodiments, these details are not intended to limit the scope of the disclosure as defined in the appended claims. For example, the vibratory motor may be coupled to the inner eccentric and the linear actuator may be coupled to the outer eccentric. Other aspects, objects and advantages of this disclosure can be obtained from a study of the drawings, the disclosure, and the appended claims.

Claims

1. A vibratory system for a compactor, comprising:

a first eccentric;

a second eccentric rotatably and coaxially positioned with respect to the first eccentric; and

a key shaft rotatably coupled to the second eccentric and rotatably coupled to the first eccentric.

2. The vibratory system of claim 1, wherein the key shaft comprises

an axial spline portion;

a helical spline portion, and

wherein the first eccentric is rotatably coupled to the first eccentric through the helical spline portion.

3. The vibratory system of claim 2, further comprising:

an actuator having an extension and a retraction stroke and coupled to the key shaft, and

wherein the second eccentric rotates in a first angular direction with respect to the first eccentric on the extension stroke and rotates in a second angular direction opposite the first angular direction with respect to the first eccentric on the retraction stroke.

4. The vibratory system of claim 3, further comprising:

an adapter coupling the actuator to the key shaft, the adapter including at least one bearing.

5. The vibratory system of claim 2, wherein the second eccentric is positioned within the first eccentric.

6. The vibratory system of claim 5, wherein the axial portion of the key shaft slides within the second eccentric.

7. The vibratory system of claim 5, further comprising:

wherein the second eccentric rotates in a first angular direction with respect to the first eccentric on the extension stroke and rotates in a second angular direction opposite the first angular direction with respect to the first eccentric on the retraction stroke,

wherein the first and the second eccentric each have a radial alignment hole, and the axes of the radial alignment holes align when the first eccentric and the second eccentric are in phase.

8. The vibratory system of claim 5, further comprising:

wherein the first and the second eccentric each have a radial alignment hole, and the axes of the radial alignment holes align when the first eccentric and the second eccentric are 180 degrees out of phase.

9. The vibratory system of claim 2, wherein the first eccentric has a helical bore and further comprising:

a helical screw positioned in the helical bore and coupled to the key shaft, the helical spline positioned on the helical screw.

10. The vibratory system of claim 2, further comprising:

a motor coupled to the first eccentric and configured to rotate the first eccentric about an axis.

11. The vibratory system of claim 2, further comprising:

a motor coupled to the second eccentric and configured to rotate the second eccentric about an axis.

12. A compactor, comprising:

a drum having a drum axis; and

a vibratory system rotatably positioned within the drum about the drum axis and having:

a first eccentric;

a key shaft rotatably coupled to the second eccentric and rotatably coupled to the first eccentric through a helical spline.

13. The compactor of claim 12, wherein the key shaft comprises

an axial spline portion;

a helical spline portion; and

14. The compactor of claim 13, wherein the vibratory system further includes:

wherein the second eccentric rotates in a first angular direction with respect to the first eccentric on the extension stroke and the second eccentric rotates in a second angular direction opposite the first angular direction with respect to the first eccentric on the retraction stroke.

15. The compactor of claim 12, wherein the vibratory system further includes:

16. The compactor of claim 12, wherein the second eccentric is positioned within the first eccentric.

17. The compactor of claim 16, wherein the axial portion of the key shaft slides within the second eccentric.

18. The compactor of claim 16, wherein the vibratory system further includes:

wherein the second eccentric rotates in a first angular direction with respect to the first eccentric on the extension stroke and rotates in a second angular direction opposite the first angular direction with respect to the first eccentric on the retraction stroke, and

19. The compactor of claim 16, wherein the vibratory system further includes:

20. The compactor of claim 13, wherein the first eccentric has a helical bore and the vibratory system further includes:

21. The compactor of claim 13, wherein the vibratory system further includes:

a motor coupled to the first eccentric and configured to rotate the first eccentric about the drum axis.

22. The compactor of claim 13, wherein the vibratory system further includes:

a motor coupled to the second eccentric and configured to rotate the second eccentric about the drum axis.

23. A method for providing a vibratory system for a compactor, comprising:

providing a first eccentric, a second eccentric, and a key shaft;

rotatably and coaxially positioning the second eccentric with respect to the first eccentric;

rotatably coupling the key shaft to the second eccentric; and

rotatably coupling the key shaft to the first eccentric.

24. The method of claim 23, wherein the key shaft comprises

an axial spline portion;

a helical spline portion; and

wherein the step of rotatably coupling the key shaft to the first eccentric is done through the helical spline portion.

25. The method of claim 23, further comprising:

coupling a motor to the first eccentric, the motor configured to rotate the first eccentric about an axis; and

coupling an actuator to the key shaft, the actuator having an extension and a retraction stroke, wherein the second eccentric rotates in a first angular direction with respect to the first eccentric on the extension stroke and rotates in a second angular direction opposite the first angular direction with respect to the first eccentric on the retraction stroke.

26. The method of claim 23, further comprising:

coupling a motor to the second eccentric, the motor configured to rotate the second eccentric about an axis; and