US3437157A

US3437157A - Diesel pilehammer

Info

Publication number: US3437157A
Application number: US598663A
Authority: US
Inventors: Kenneth E Bailey; Leland J Frahm; Theodore M Leigh
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1966-12-02
Filing date: 1966-12-02
Publication date: 1969-04-08
Anticipated expiration: 1986-04-08
Also published as: DE1709401A1; GB1209318A; JPS4818050B1; DE1709401B2; DE1709401C3; DE1634455B2; DE1634455A1

Description

- April 8, 1969 5, BAlLEY ET AL DIESEL PILEHAMMEH Filed Dec. 2. 1966 FIG.

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INVENTORS KENNETH E. BAILEY LELAND J. FRAHM THEODORE M. LEIGH ATZY April 8, 1969 K. E. BAILEY ET AL DIESEL PILEHAMMER Sheet Filed Dec. 2. 1966 TORS INVEN KENNETH E. BAILEY LELAND J. FRAHM THEODORE M. LEIGH ATT April 8, 1969 K. E. BAILEY ET AL DIESEL PILEHAMMER Filed Dec. 2. 1966 Sheet .5 of8 IN VEN TORS KENNETH E. BAILEY LELAND J. FRAHM THEODORE M. LEIGH ATTY April 8, 1969 K. E. BAILEY ETAL 3,437,157

DIESEL PILEHAMMER Filed Dec. 2,.1966 Sheet 4 INVENTORS KENNETH E. BAILEY LELAND J. FRAHM THEODORE M LEIGH ATT Y April 8, 1969 K. E. BAILEY ET AL 3,437,157

DIESEL PILEHAMMER Filed Dec. 2. 1966 Sheet 5 of a F/GQ.

I INVENTORS O3 96 KENNETH E. BAILEY I02 08 LELAND J. FRAHM THEODORE M. LEIGH I07 /o4 /oo /o9 ATTY K. E. BAILEY ETAL April 8, 1969' DI ESEL PI LEHAMMER Sheet Filed Dec.

INVENTO ETH E. BA LELAND J. FRAHM THEODORE M. LEIGH RS ILEY KENN ATTY April 8, 1969 BMLEY ET AL DIES EL PILEHAMMER Sheet Filed Dec. 2, 1966 BAILEY J. FRAHM ATT Y;

INVENTORS ETH E.

KENN

LELAND THEODORE M. LEIGH f) m n WW mm a 9 @E United States Patent 3,437,157 DIESEL PILEHAMMER Kenneth E. Bailey, Marion, Iowa, Leland J. Frahm, Mendota, Ill., and Theodore M. Leigh, Cedar Rapids, Iowa, assignors to FMC Corporation, a corporation of Delaware Filed Dec. 2, 1966, Ser. No. 598,663 Int. Cl. E21b 1/00; E21c 3/00; B25d 9/00 US. Cl. 173133 22 Claims ABSTRACT OF THE DISCLOSURE A diesel pilehammer comprising a housing having a bore formed therein for receiving a free piston in sealing engagement therewith and slidably disposed therein for reciprocating axial movement; portions of the piston being formed to cooperate with corresponding portions of the housing for defining a scavenging chamber and a power chamber interconnected by a conduit including a valve for allowing gases to pass only in one direction from the power chamber to the scavenging chamber. The housing is formed with a port having valve means to allow gases to pass in one direction from the scavenging chamber to the atmosphere as the piston moves in a direction to decrease the volume of the scavenging chamber. The housing is also formed with a port for allowing the passage of gases to and from the power chamber. The free piston and housing cooperate to define a combustion chamber within the power chamber when the free piston is in a position providing a minimum volume in the power chamber. The diesel pilehammer further comprises appropriate fuel injection means for delivering fuel to the combustion chamber to be ignited and lifting means for raising the piston to its starting position. The lifting means includes a member for engaging a downwardly facing surface formed on the piston and a latch mechanism for automatically retaining the lifting means in its lowermost position to facilitate control of the entire hammer at all stages of the hammer operation. The diesel pilehammer, as described above, is a preferred embodiment of one of several apparatus for carrying out a method of operating a diesel pilehammer including igniting a compressed fuelair mixture in a combustion chamber underlying the piston to cause the piston to ascend; evacuating a space separate from the combustion chamber during the ascent of the piston; permitting gases to flow to said evacuated space from the chamber underlying the piston while also admitting air into the latter space for the scavenging thereof during the ascent of the piston; reversing the direction of movement of the piston due to a reversal of the imbalance of forces acting thereon; forcing the gases in the previously evacuated space to flow to the atmosphere during the descent of the piston; confining and compressing air in the combustion chamber during the descent of the piston; and injecting fuel intothe compressed air to be ignited for initiating a subsequent cycle.

This invention relates to new and useful improvements in diesel pilehammers and deals more particularly with the operation and starting thereof.

A diesel pilehammer is one application of a one cylinder unbalanced free piston diesel engine, wherein the piston strikes an anvil slidable in the bore and resting on a pile. The impact of the piston on the anvil provides the principal impetus to drive the pile. The combustion of the fuel air mixture beneath the piston raises it to a position where it will have suificient impetus to again descend driving the pile further, and simultaneously the combustion provides a driving force on the ram.

Difficulties have been encountered in the past in the use of this type hammer when driving piling into soft 3,437,157 Patented Apr. 8, 1969 ground. On previous designs, once a hammer was started on a low resistance pile it sometimes ceased to continue the cycle after one or more strokes. The reason for this was that on low resistance piling, the forces of combustion acting to raise the ram were reduced by the rapid drop of the anvil. Thus the length of ram stroke was reduced and the amount of fresh air drawn in by the scavenging system was reduced. The reduced amount of oxygen trapped on the subsequent compression stroke further reduced the forces of combustion resulting in still shorter ram stroke length and thus the hammer ceased to operate after a few strokes.

A further difficulty encountered with scavenging systems on some existing diesel pilehammers is caused from their utilizing energy of the descending ram for scavenging the power chamber. The principal driving energy is supplied by the energy of the descending piston, and any utilization of this energy for other purposes subtracts from the driving force.

To start the diesel cycle the free piston is mechanically raised to a starting position and then released to compress the fuel-air mixture for ignition. Existing designs of lifting mechanisms have required a slot in the cylinder wall to provide access for the lifting lever to engage the piston and/or have been a complex over-center toggle linkage which is subject to failure. The lifting mechanisms requiring the access slot along the cylinder are mounted on or adjacent to the side of the hammer. Therefore, the lifting force is applied in a manner to cause an off-center skewing force to the hammer. This imbalance of forces tends to cock the hammer and cause the driving forces to be improperly applied.

It is the primary object of the invention to improve the operation of a diesel pilehammer on all types of piling, especially piling driven into soil offering low resistance.

Another important object of the invention is to provide a self-scavenging system that will supply sufficient oxygen for combustion when the piston stroke is shortened due to low resistance piling.

Another object of the invention is to provide a scavenging system that does not subtract energy from the descending piston that could be utilized for pile driving.

Still another object of the invention is to provide an integral scavenge pump formed by the annular chamber between stepped diameter portions of the ram and cylinder.

A further object of the invention is to provide a reliable piston lifting mechanism having few parts.

A still further object of the invention is to provide a lifting mechanism, having few parts, that will permit oncenter lifting of the piston for starting.

Other objects and advantages of the invention will be apparent during the course of the following description.

While, for the sake of clearness in illustration, the hammer is shown and described in use as a pilehammer with the cylinder in a substantially upright position, but it is obvious that the hammer may be arranged to operate in a position inclined to the vertical as may be required for various types of uses to which the hammer is applicable.

In the accompanying drawings, forming a part of this specification and in which like reference characters are employed to designate like parts throughout:

FIGURE 1 and 1a is a side elevational view, partly in section, of a diesel pilehammer embodying the invention;

FIGURE 2 and 2a is a rear elevational view, partly broken away, of a diesel pilehammer embodying the invention;

FIGURE 3 and 3a is a front elevational view, partly broken away, of a diesel pilehammer of the present invention;

FIGURE 4 is a fragmentary view, partly elevational and partly sectional, showing the relative position of the scavenging ports and intake-exhaust ports in the housings of the diesel pilehammer illustrated in FIGS. 1, 1a, 2, 2w, 3 and 3a.

FIGURE 5 is a sectional view taken on line 55 of FIG. 4 showing the cross-section of the intake-exhaust ports;

FIGURE 6 is a sectional view taken on line 6-6 of FIG. 4, showing a plan view of the scavenging ports;

FIGURE 7 is a sectional view taken on line 7-7 of FIG. 6;

FIGURE 8 is an enlarged fragmentary view of the lower portion of the lifting mechanism shown in FIG. 2a;

FIGURE 9 is a sectional view of the lifting mechanism illustrated in FIG. 8;

FIGURES 10, 11, 12, 13, 14, and are schematic representations of the operating cycle of the diesel pilehammer employing the first embodiment of the present invention;

FIGURES 16, 17, 18, 19, and 21 are schematic representations of the operating cycle of a diesel pilehammer employing the second embodiment of the present invention;

FIGURE 22 is a schematic representation of the third embodiment of the present invention;

FIGURE 23 is a thermodynamic digram showing the pressure-displacement relationship of the power chamber of a diesel pilehammer embodying the present invention;

FIGURE 24 is a thermodynamic diagram showing the pressure-displacement relationship of the scavenge chamber of a diesel pilehammer embodying the present invention;

FIGURE 25 is a thermodynamic diagram showing the pressure-displacement relationship of the bounce chamber of a diesel pilehammer embodying the present invention.

In the drawings, wherein are shown the preferred embodiments of this invention, and first particularly referring to FIGS. 1, 1a, 2, 2a, 3, and 3a, there is shown a diesel pilehammer 27 having an upper cylinder 28 and a lower cylinder 29 connected by bolting together

mating flanges

31 and 32. The bore 33 of the upper cylinder 28 is of a larger diameter than the bore 35 of the lower cylinder 29. At the upper end of the upper cylinder 28, an upper cylinder head 34 is secured to the upper cylinder 28 by bolting together

mating flanges

36 and 38. This upper cylinder head 34 contains a guide sheave assembly 37 to guide the starting and lifting rope from the off-center starting mechanism to an on-center hoisting location.

The lower cylinder is closed at its lower end by the anvil 39 which is slidable in the lower portion of the bore of the lower cylinder 29. The anvil 39 is retained by means of the anvil retainer 41 which is bolted to the bottom flange of the lower cylinder 29. The anvil 39 is equipped with compression rings 42a to seal the lower end of the bore 35 of the lower cylinder 29.

Beneath the anvil 39 and guided by the anvil retainer 41 is a cushion adapter plug 43 which transmits the energy from the anvil 39 to the cushion 44 which fits over the lower end of the cushion adapter plug 43, and has a spherical lower surface 45 which mates with the spherical upper surface of the driving head 42. The cushion adapter plug 43 has a central outwardly extending flange 46 which projects a short distance below the bottom surface 47 of the anvil retainer 41. In the space between the flange 46 and the bottom surface 47 of the anvil retainer 41 an annular ring of elastomeric material 48 is located. The elastomeric material serves as a recoil dampener and absorbs the energy of recoil from a pile being driven. It also absorbs the shock if the hammer is dropped on the pile or if the hammer bounces on the pile during operation.

The anvil retainer 41 has a further function of providing a bearing surface for the larger diameter portion 49 of the anvil 39 so that sideward thrusts that would tend to cock the anvil are adequately resisted. Such side thrusts can be caused by pile misalignment, eccentricity and whip. The anvil retainer 41 also supports an alignment pin 51 which enters a mating hole 52 in the enlarged diameter portion 49 of the anvil 39. The purpose of this pin 51 is to prevent rotation of the anvil 39 during operation.

Within both the upper cylinder 28 and the lower cylinder 29 is the ram 55, which is free to reciprocate vertically. The lower portion 56 of the ram '55 is in sealing engagement with the bore 35 of the lower cylinder 29 and defines a generally cylindrical power chamber 50 between the lower end of the ram and the anvil 39. The lower portion 56 contains a wear ring 57 and compression rings 58 near its lower end to prevent leakage of gases between the Wall of the cylinder bore 35 and the lower portion of the ram 56. The wear ring has the function of acting as a bearing ring to support the ram so that the cylinder bore 35 is prevented from coming in direct contact with the ram material. Near the upper end of the smaller diameter portion 56 of the ram 55 the diameter is varied to form a cam surface 59 to actuate a cam follower 60 that drives the fuel pump 61 and the lubrication pump 62. A short distance above the cam surface 59, the ram diameter is increased to form a larger diameter portion 63. This larger diameter portion 63, which operates only in the bore 33 of the upper cylinder 28 has compression ring 64 at both its upper and lower ends and a wear ring 65 therebetween. This larger diameter portion 63 of the ram 55 divides the upper cylinder in two parts; a lower annular space which forms a scavenging chamber 53 and a cylindrical upper space which is a bounce chamber 54.

The housing is formed with outwardly extending ribs on which various plates and accessories are attached to give the housing a substantially rectangular cross-section. FIGS. 1 and 1a illustrate one of two similar but opposite handed sides of the diesel pilehammer 27. Illustrated in FIGS. 2 and 2a is the back of the hammer, and in FIGS. 3 and 3a is the front of the hammer. For purposes of describing the exterior of the hammer the two sides of the hammer 27 will first be described as they are illustrated in FIGS. 1 and la.

Formed as part of the upper cylinder are two guide angle pads 66 on which guides may be mounted to fit into corresponding leads to guide the travel of the hammer in the direction that the pile is to be driven. Formed as part of the lower cylinder 29 are two radially outwardly extending ribs 67. These ribs are also illustrated in FIG. 6. The ribs 67 in cooperation with an outwardly extending flange 68, the flange 32, and a cover plate 69 bolted to the ribs form a scavenging passageway 70. The scavenging passageway 70 opens into the annular scavenging chamber 53 through openings 76 in the flange 32. The rib 67 toward the front side of the lower cylinder 29 is formed with openings 71 allowing gases to pass to and from a space defined in the front portion of the housing, and to be described below.

Also illustrated in FIG. 1a is the combustion chamber 72 defined by a semi-spherical indentation 73 in the ram 55 and a corresponding semi-spherical indentation 74 in the anvil 39. Opening from the semi-spherical indentation 74 in the anvil 39 is a cylindrical passageway 75. Mounted in the lower cylinder 29 is an injection nozzle 78 which injects fuel for combustion through the passageway 75 into the combustion chamber when the ram 55 nears its downward most position.

Formed in each side of the lower cylinder 29 are three intake-exhaust ports 77. Referring now to FIG. 5 wherein is shown a cross-sectional view of these ports, the intakeexhaust ports 77 open from the power chamber 50 to the atmosphere to allow the exhaust gases to blow-down into the atmosphere and to allow air to flow into the power chamber for scavenging. The ports 77 are shaped to direct the incoming air down into the cylinder toward the anvil to sweep burned gases out of the power chamber 50 and combustion chamber 72 during scavenging. The intake-exhaust ports 77 are located so as to be the first ports in the lower cylinder to open as the ram rises during the power stroke.

Referring now specifically to FIGS. 2 and 2a, wherein is illustrated the back view of the diesel pilehammer 27, reference character 78 refers to covers for the intake-exhaust ports which prevent foreign material from entering the power chamber when the hammer 27 is not in operation. Toward the top end of the upper cylinder 2.8 are shown a series of four ports 81 which open from the bounce chamber 54, in the upper cylinder 28, into an auxiliary bounce chamber 86 defined by the exterior of the housing and a box shaped cover plate 85. The above mentioned auxiliary bounce chamber 86 serves as an overflow for air compressed in the bounce chamber 54 in the upper cylinder head 28 during the rise of the ram. If the ram moves past its normal upward most position, it closes off the ports 81 and enters a confined safety space in which the gases are rapidly compressed increasing the pressure in the confined safety space and retarding the upward movement of the ram to prevent the ram from striking the cylinder head 34.

Located on the lower cylinder 29 on the back side is the ram lifting mechanism 30 which is further illustrated in FIGS. 8 and 9. The ram lifting mechanism 30 includes a guide block 91 slidable vertically in ways 92. Attached to and extending upward from the guide block 91 is a push rod 93 which passes through an opening 89 in flange 32 and engages the annular under surface 90 of the larger diameter portion 63 of the ram 55. The push rod is guided through the upper flange 32 of lower cylinder 29 by means of a guide bushing 94 which also serves as a seal to prevent air leakage into the annular scavenging chamber 53. The guide block 91 also serves as the attachment point of the hoist rope 95 used to position and start the hammer.

The guide block 91 contains a latch mechanism used to lock the starting mechanism 30 in the downward position when using the hoist rope 95 to lift and position the hammer 27. Located in the guide block 91 is a spring loaded pin 96 which engages a latch block 97 bolted to the lower cylinder 29. Pivoted on the latch block 97 is a spring biased push arm 98 which engages the spring loaded pin 96. Normally the pin is in its outward position to engage the latch block 97 and hold the lifting mechanism 30 in its downward most position so that the entire pilehammer 27 may be hoisted and positioned by means of the 'hoist rope 95. Upon tensioning of the latch release rope 99, the arm 98 slides the pin 96 into the guide block 91 to allow the hoist rope 95 to raise the push rod lifting mechanism 30 to engage and lift the ram 55 to its proper starting position. The tension on the hoist rope 95 is then released allowing the ram 55 and push rod lifting mechanism 30 to descend compressing fuel and air in the combustion chamber 72 for ignition. The push rod lifting mechanism 30 has its downward descent stopped by a recoil dampener 100 located on the lower cylinder housing 29 directly beneath the guide block 91. The recoil dampener 100 includes a cup shaped housing 101 containing a sleeve 102 having a series of openings 106 through its lower position. The sleeve 102 has a stepped bore to retain the pin 103, biased upward by the spring 104, within the bore of the sleeve 102. Hydraulic fluid is contained within the cup 101 and sleeve 102 upon downward movement of the pin 103, due to the descent of the guide block 91, the hydraulic fluid is compressed and forced through the openings 106 in the sleeve 102 and into the annular space 107 defined between the outer wall 108 of the sleeve and the inner wall 109 of the housing 101. The resistance of the hydraulic fluid to flow through the openings 106 causes the lifting mechanism 58 to come to a smooth halt allowing time for the spring loaded pin 96 to engage the latch block 97.

The hoist rope 95 extends from the sheave guide mechanism 37 through a tube 111 passing through the auxiliary bounce chamber 86. The tube 111 is welded and sealed at both of its ends 112 so that the auxiliary bounce chamber 86 is hermetically sealed.

The hoist rope guide mechanism 37 includes a housing 110 having a flared opening 114 at its upper portion through which the hoist rope enters from an independent lifting means (not shown). Also formed in the housing is a radial slot 115 which opens into the flared opening and extends the entire length of the housing. Passing through the housing substantially perpendicular to and intersecting the slot 115 are two pins 116 which are fitted into appropriate holes 113 in the housing 110. One hole 113 is located below and in back of the other hole. Pivotally mounted on the pins 116 are two

sheaves

117 and 118 located within the slot 115. Referring again specifically to FIG. 1 wherein is shown a side cross-sectional view of the hoist rope guide means 37, the first sheave 117 is located so that the hoist rope enters axially of the diesel pilehammer 27 and passes under the sheave 117. The second sheave 118 is located below and in back of the first mentioned sheave 117 so that the rope passes from the first sheave 117 and over the second sheave 118 and extends down the side of the housing through the tube 111. The purpose of the guide means 37 is to cause the hoisting force to be exerted on a line axially with the center of the housing to prevent any off-center force from cocking the angle of the pile hammer 27 while it is lifted and positioned on a pile to be driven. The flared opening 114 on the housing 110 causes the hoist rope to enter the guide sheaves 117 and 118 properly regardless of the amount of off lead present.

Referring now specifically to FIG. 3, wherein is shown the front view of the diesel pilehammer 27, reference character 119 refers to equalizing ports positioned to be open when the ram is at its upward most position allowing passage of air to the annular scavenging chamber 53 from the atmosphere to relieve any vacuum. The equalizing ports 119 are also open When the ram is in its lower most position allowing air to flow from the atmosphere into the cylindrical bounce chamber 54 to replace air lost therefrom through the compression rings during compression of the gases in the bounce chamber 54. While the hammer is not in operation the equalizing ports 119 are sealed by the cover 120. Referring now specifically to FIGS. 1, la, 3, 4, 6, and 7 for a description of the six scavenging ports denoted by reference character 122. The scavenging ports 122 are located to open subsequent to the opening of the intake-exhaust ports 77 as the ram rises during the power stroke. The six scavenging ports 122 open into a chamber 123 defined by two radially extending ribs 67 and two outwardly extending flanges 124 and a cover plate 125 bolted to the ribs. The lower cylinder 28 is formed with six rectangular lateral openings 131 and six three-sided deflector plate projecting outward from the openings to form the scavenging ports so that the gases are directed up through the chamber 123 during the scavenging cycle.

During the power stroke the ram rises to create a vacuum in the scavenging chamber 53 which draws air through the power chamber 50 to facilitate the scavenging thereof. During scavenging the gases pass from the atmosphere through the intake-exhaust ports 77 and into the power chamber 50 in a swirling fashion. Thence the gases flow from the power chamber 50 through the scavenging ports 122 into the chamber 123. The flow continues through the openings 71 in the nb 67 into the scavenging passageways 70 on either side of the pilehammer 27. The gases then enter the annular scavenging space 53 through the openings 76 in the flange 32. As the ram descends it closes the scavenging ports 122 and compresses the gases in the annular scavenging chamber 53 forcing the gases through the passageway into the chamber 123 and then out the scavenging valve 126. The scavenging valve 126 includes four openings 121 in the plate 125 covered by two thin tempered metal plates 127, bolted along one edge to plate 125, which act as reed valves to allow passage of gases only from the chamber 123 when the pressure therein is raised a predetermined amount above atmospheric pressure. There are two sets of three scavenging ports 122, one set located on each of the two sides of the front portion of the diesel pilehammer 27. The arrangement of the scavenging ports 122 in relationship to the intake-exhaust ports 77 is illustrated in FIG. 4.

Also attached to the front side of the diesel pilehammer 27 is the fuel tank 128 with the lubrication tank 133 located therein. Directly beneath the fuel and lubrication tanks is a protector 129 to guard the fuel and

lubrication tanks

128 and 133 and the associated hoses and fittings. Located on the lower cylinder 29 is the lubrication pump 62 which is actuated by a cam follower 60 which engages the cam surface 59 on the ram. On each stroke of the ram a predetermined amount of lubrication is dispersed to selected points within the bore of the two

cylinders

28 and 29. Also actuated by the cam follower 60 is the fuel pump mechanism 61 which is of a standard type, as illustrated in American Bosch catalog number APF-lCC 18OT-3035C. The fuel pump delivers a controllable amount of fuel to the nozzle 78 which injects said fuel into the spherical combustion chamber 72. The amount of fuel dispersed is controlled remotely by the controller 130 located generally a distance away from the diesel pilehammer. Also attached to the front side of the diesel pilehammer is a starting fluid injector which is described in Patent No. 3,161,184 which only on the starting stroke may inject a predetermined amount of starting fluid into the combustion chamber.

Method of operation FIGS. 10, ll, 12, 13, 14, and 15 illustrate the cycle of operation of a diesel pilehammer 27 as illustrated in FIGS. 1 through 9 and show the position the ram and the condition of the various ports and valves during the cycle. For purposes of illustration, FIGS. 10 through employ a solid arrow to show the movement of exhaust gases, a partially shaded arrow to show the movement of a mixture of exhaust gases and fresh air, and an open arrow to show the movement of fresh air.

Referring now specifically to FIG. 10, ram 55 is at the bottom of its stroke and impacting anvil 39 to start driving pile 151. Scavenging port 122 and intake-exhaust ports 77 are closed, and air confined in the combustion chamber 72 is compressed. Equalizing ports 119 are open to allow any air lost through the compression rings during the compression of air in the bounce chamber to be replaced, to bring bounce chamber pressure up to atmospheric pressure. Nozzle 78 has injected fuel into combustion chamber 72 and, ignition of the fuel air mixture is taking place, raising the pressure between ram 55 and anvil 39 to start the ram moving upward and maintaining a driving force on pile 151.

FIG. 11 illustrates the condition of the hammer subsequent to the combustion of the fuel air mixture in combustion chamber 72. Ram 55 has risen a sufiicient amount to close equalizing ports 119. Cam follower 60 has descended down cam surface 59 on ram 55 allowing fuel injection pump 61 to recharge. The upward movement of the ram creates a sub-atmospheric pressure in annular scavenging chamber 53 and compresses the confined air in bounce chamber 54 and auxiliary bounce chamber 86. The compression of the confined air in the

bounce chambers

54 and 86 transfers some of the kinetic energy of the ram 55 into potential energy of the compressed air. Ram 55 in the position shown in FIG. 11 is still sealing scavenging ports 122 but has allowed intake-exhaust ports 77 to open, permitting burned gases in power chamber 50 to blow-down to atmospheric pressure.

FIG. 12 shows ram 55 after it has moved further upward, opening scavenging ports 122. Since scavenging chamber 53 and the scavenging passageway 70, prior to the opening of scavenging ports 122, were at a sub-atmospheric pressure, air at atmospheric pressure flows in through intake-exhaust ports 77 scavenging power chamber 50 and combustion chamber 72 of burned gases. The

burned gas, scavenging air mixture is drawn through scavenging ports 122 and into passageway 70 and scaveng ing chamber 53. As ram 55 continues upward movement, it increases the volume of annular scavenging chamber 53 drawing additional fresh air from the atmosphere through power chamber 50 and into scavenging chamber 53. This process continues until equalizing ports 119 are opened into scavenging chamber 53 to establish atmospheric pressure therein. The opening of equalizing ports 119 into the scavenging chamber 53 is not essential to the operation and should not occur until ram 55 has moved upward a sufficient distance to provide for adequate scavenging. Upward movement of ram 55 into bounce chamber 54 compresses the confined air therein imparting additional energy from the ram to compress air.

Referring now specifically to FIG. 13, the ram 55 is illustrated in its upward most position. As ram 55 has been moving upward, energy imparted to it by the forces of combustion undergoes conversion to potential energy of the ram, energy imparted to the air compressed in bounce chamber 54 and auxiliary bounce chamber 86, and work performed in reducing pressure in scavenging chamber 53 plus small amounts of work overcoming friction of the ram and windage of air and gases moved at atmospheric pressure. When all the kinetic energy of the ram 55 has thus been converted, the ram ceases its upward movement and begins its downward stroke.

FIG. 14 shows ram 55 after it has been acted upon by gravity and the pressure of the air in bounce chamber 54 which begins the descent of the ram. The now highly dilute burned gases in scavenging chamber 53 and passageway 70 are driven out scavenging ports 122, across power chamber 50 and out intake-exhaust ports 77. Excess air beneath ram 55 and above intake-exhaust ports 77 also is blown out ports 77. Air in bounce chamber 54 expands to transfer the potential energy stored therein back to ram 55 as kinetic energy.

Referring now particularly to FIG. 15, wherein is shown ram 55 just prior to injection of fuel and combustion. As ramv 55 descends to the point shown in FIG. 15 it closes scavenging ports 122 and decreases the volume of scavenging chamber 53 raising the pressure therein. When the pressure in scavenging chamber 53 and scavenging passageway 70 rises a suflicient amount above atmospheric pressure, scavenging valve 126 opens to vent the gases drawn into the scavenging chamber during the scavenging cycle. Upon closure of intake-exhaust port 77 by ram 55, air confined in power chamber 50 is compressed between ram 55 and anvil 39. As ram 55 approaches anvil 39 cam follower 60 rides up cam surface 59, causing fuel pump 61 to begin delivery of fuel to injector 78. Bounce chamber air continues to expand imparting kinetic energy to ram 55 until equalizing ports 119 open. When ram 55 strikes anvil 39, fuel injection is complete and ignition begins. Impact of ram 55 on anvil 39 delivers the rams energy to anvil 39 and thence to pile 151 through cushion block 44 and driving head 42. After impact, ram 55 rises under action of the expansion of the burning fuel-air mixture, and this expansion, acting on the now descending anvil 39 transfers additional energy to the pile 151.

FIGS. 16, l7, 18, 19, 20, and 21 illustrate the cycle of operation of a diesel pilehammer 27 including the second embodiment of the invention. As described above the second embodiment of the invention is substantially the same as the first embodiment with the inclusion of reed valve 141 to allow flow of gases only from power chamber 50 to passageway 70, and not in the reverse direction. Since the operation of equalizing ports 119, scavenging ports 122, scavenging valves 126, and intake-exhaust ports 77, are the same as in the description of the method of operation of the first embodiment of the invention, they will not again be described. The shading of the arrows shown in the figures illustrating the cycle of operation of the second embodiment of the invention have the same significance as in the description of the first embodiment operation.

Referring now specifically to FIG. 16, wherein ram 55 is shown at the bottom of its stroke. Reed valves 141 are closed preventing the flow of gases through scavenging ports 122. The slight positive pressure in scavenging passageway 70 holds the valves 141 closed.

Ram 55, as illustrated in FIG. 17, subsequent to ignition has risen a slight amount but yet still seals scavenging ports 122. Since scavenging ports 122 have not yet opened, reed valve 141 still is in its closed position.

After ram 55 has risen a suflicient amount to open scavenging ports 122, as illustrated in FIG. 18, the subatmospheric pressure in scavenging chamber 53 and passageway 70 causes reed valves 141 to move to their open position and remain there until the pressure in the passageway 70 becomes atmospheric. FIG. 19 shows the ram at a position opening equalizing port 119 into scavenging chamber 53 raising the pressure therein to atmospheric allowing reed valve 141 to close.

FIGS. 20 and 21 show ram 55 during its descent creating a slight positive pressure in scavenging chamber 53 and passageway 70 closing 01f reed valves 141 and preventing the flow of the dilute burned gases back into power chamber 50. Excess air beneath ram 55 and above intake-exhaust ports 77 is blown out ports 77. The ram confines air within power chamber 50 and compresses said confined air prior to injection of fuel and the combustion of the fuel air mixture to begin the next cycle.

FIG. 22 is a schematic representation of the third embodiment of the invention and corresponds to FIG. and FIG. 16, respectively, of the first embodiment and second embodiment of the invention. In the other embodiments of the invention the equalizing port 119 opened to the atmosphere, as ram 55 approached the bottom of its stroke, in order to make up the air lost during compression of air in bounce chamber 54. In the third embodiment of the invention bounce chamber 54 is connected by conduits 143 to the scavenging passageways 70. As ram 55 descends a slight positive pressure is created in scavenging chamber 53 and scavenging passageway 70. This embodiment of the invention allows the ram as it approaches the bottom of its stroke to open port 145 connecting the slight positive pressure in scavenging passageway 70, by means of the conduit 143, to bounce chamber 54 to make up any air lost from the bounce chamber during compression of the gases therein on the upstroke. Since the port 145 is connected to scavenging passageway 70' the negative pressure created during scavenging is not vented to the atmosphere, and the effective scavenging cycle is increased.

The operation subsequent to combustion of a pilehammer including the third embodiment is the same as is illustrated in FIGS. 11, 12, 13, 14, and and described above.

Thermodynamic cycle FIGS. 23, 24, and show the pressure-displacement diagrams for the first embodiment of this invention. For purposes of presentation diagrams of power chamber 50, scavenging chamber 53, and bounce chamber 54 are each shown separately. Vertical scales have been distorted so that ordinate values of pressure are not to scale and do not depict true relative values. This is done for clarity, since atmospheric pressure (14.7 p.s.i.a.) would otherwise not be apparent when compared to peak compression pressure (500 to 600 p.s.i.a.) and peak combustion pressure (1,000 to 1,200 p.s.i.a.). Pressure-displacement diagrams are used instead of pressure-volume diagrams so that the port and stroke relationship can be properly related between the different curves.

Referring now specifically to FIG. 23, wherein is shown the cycle of power chamber 50. Starting at point 161 at the extreme left end of the curve, which represents the top of the stroke, the pressure below ram 55 in power chamber is atmospheric pressure. As ram descends (moving toward right along curve), the pressure remains atmospheric until intake-exhaust ports 77 are closed (represented by point 162). After intake-exhaust ports 77 are closed the pressure beneath ram 55 rises approxi mately adiabatically reaching peak compression pressure at bottom of stroke (represented by point 163). Assuming constant volume combustion, the pressure rises vertically to peak combustion pressure indicated by point 164. Actually both anvil 39 and ram 55 move during the combustion pressure rise, but for simplicity a constant volume pressure rise is assumed. Upward movement of ram 55 (moving toward the left along the graph) causes pressure to drop'approximately adiabatically to point 165 corresponding to the opening of intake-exhaust ports 77. At this point blow-down of burned gases drops the pressure in power chamber 50 to atmospheric where it remains for the rest of the cycle.

Referring now specifically to FIG. 24, wherein is shown the thermodynamic cycle of scavenging chamber 53. Starting at the extreme left end of the curve (top of the stroke indicated by point 167), the pressure below the enlarged diameter of ram 55 in annular scavenging chamber 53 is atmospheric since equalizing ports 119, scavenging ports 122, and intake-exhaust ports 77 are open to the atmosphere. As ram 55 descends pressure in scavenging chamber 53 remains approximately atmospheric until the bottom of the stroke (indicated by point 168). When scavenging ports 122 are closed, there is a slight rise in pressure which is required to open scavenging valve 126. This pressure increase however is nominal and is here considered negligible. Upward movement of the ram (toward the left on the graph) now causes approximate adiabatic reduction of pressure below atmospheric. When the scavenging ports 122 open (represented by point 169), gases from the power chamber 50 and air from the now opened intake-exhaust ports 77 raise the pressure quickly to atmospheric where it remains for the rest of the cycle. The closing of the equalizing port 119 on the down stroke and its opening on the up stroke has no influence on the pressure-displacement relationship. Port 119 only serves to provide some incidental aeration of scavenging cyclinder 53 which actually is a nonessential function.

FIG. 25 illustrates the thermodynamic cycle of the compression of air in bounce chamber 54 and its associated auxiliary bounce chamber 86. The description of this curve will start at point 171 (at the extreme right end of the diagram, bottom of the stroke) and proceed first to the left. The pressure in bounce chamber 54 and auxiliary bounce chamber 86 is atmospheric at point 171, since equalizing ports 119 are open from the bounce chamber to the atmosphere. The pressure remains atmospheric during the short rise of the ram until equalizing ports 119 are closed by ram 55. Continued rise of ram 55 causes an approximate adiabatic pressure increase to the normal top of the stroke (indicated by point 173). Descent of ram 55 results in an approximate adiabatic reduction in pressure which is shown by proceeding along the same curve as the rise of pressure to point 172. At point 172 equalizing ports 119 open into bounce chamber 54 to vent the same at which time the pressure becomes atmospheric and remains so until the equalizing ports are closed.

The thermodynamic cycle of power chamber 50, scav enging chamber 53, bounce chamber 54 and auxiliary bounce chamber 86 of the second and third embodiments of the invention are substantially the same as the thermodynamic cycle described above.

It is to be understood that the forms of this invention herewith shown and described are to be taken as a preferred example of the same, and that various changes in the shape, size, number, and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described the invention, we claim:

1. In a diesel pilehammer the combination of:

a housing having a bore,

a reciprocating free piston in sealing engagement with and slidably disposed in the bore for axial movement therein, portions of the piston cooperating with the housing to define a scavenging chamber and a power chamber each having at least one movable wall,

valve means to allow gases to pass in one direction from the scavenging chamber tothe atmosphere when a movable wall of the scavenging chamber moves in a direction to decrease the volume thereof,

a conduit connecting the power chamber and the scavenging chamber to allow gases to pass from the power chamber to the scavenging chamber upon movement of a movable wall of the scavenging chamber in a direction to increase the volume thereof,

the housing having a port to allow passage of gases to and from the power chamber,

the portions of the piston and housing defining the power chamber having opposed surfaces spaced from each other to form a combustion chamber when a movable wall of the power chamber is in a position providing a minimum volume in the power chamber,

fuel injection means to deliver fuel to the combustion chamber for ignition, and

lifting means to raise the piston to its starting position.

2. A diesel pilehammer as defined in claim 1 further characterized by:

means sealing one end of the bore and cooperating with the housing and piston to form a bounce chamber having at least one movable wall moving in a direction to decrease the volume of the bounce chamber as a movable wall of the power chamber moves in a direction to increase the volume of the power chamber.

3. A diesel pilehammer as defined in claim 2 further characterized by:

a laterally disposed chamber; and

conduit means connecting the laterally disposed chamber to the bounce chamber.

4. A diesel pilehammer as defined in claim 3 further characterized by:

the conduit means being located in a position to be shut off by the movement of the piston in a direction to decrease the volume of the bounce chamber to create a cushion of gases between the sealing means and the piston for arresting the movement thereof.

5. A diesel pilehammer as defined in claim 1 further characterized by the housing including:

an anvil sealingly retained for limited axial movement in one end portion of the bore, portions of the anvil and piston having surfaces defining walls of the combustion chamber.

6. A diesel pilehammer as defined in claim 2 further characterized by:

the housing having a port to equalize the pressure of the bounce chamber with atmospheric pressure when the movable wall of the bounce chamber is at the position to provide for maximum volume in the bounce chamber.

7. A diesel pilehammer as defined in claim 6 further characterized by:

the equalizing port opening into the scavenging chamber to equalize the pressure therein with atmospheric pressure when the movable wall of the scavenging chamber is at the position to provide for the maximum volume in the scavenging chamber.

8. A diesel pilehammer as defined in claim 2 further characterized by:

the housing having a stepped cylindrical bore providing two coaxial portions, one portion having a diameter larger than the other forming a shoulder therebetween;

the piston having a portion in sealing engagement with each of the two portions of the housing and a shoulder therebetween, the sealing means in cooperation with the larger diameter portions of the housing and piston defining the bounce chamber, the shoulders of the housing and the piston cooperating to define the scavenging chamber, the smaller diameter portions of the piston and housing defining the power chamber.

9. A diesel pilehammer as defined in claim 1 further characterized by:

valve means associated with the conduit to only allow flow of gases from the power chamber to the scavenging chamber.

10. A diesel pilehammer as defined in claim 2 further characterized by:

a conduit connecting the bounce chamber to the scavenging chamber to equalize the pressure therebetween when the movable wall of the bounce chamber is at a position providing maximum volume in the bounce chamber.

11. A diesel pilehammer including a housing, a reciprocating free piston, and means for lifting the piston wherein the lifting means comprises:

a radially outwardly projecting portion on the piston;

a lifting mechanism including a rod slidably mounted on the housing for movement parallel to the reciprocation of the piston, the rod underlying and engaging the radially outwardly projecting portion of the piston to impart the lifting force thereto;

means associated with the lifting mechanism for applying a lifting force thereto to raise the piston and for releasing the lifting mechanism to allow the mechanism to descend to its original position and to permit the piston to descend to start the diesel cycle;

a cable interconnecting the rod and the force applying means;

means for fastening the cable to the rod; and

guide means associated with the housing to direct the path of movement of the cable.

12. A diesel pilehammer as defined in claim 11 wherein the guide means comprises:

a sheave mounted on the upper portion of the housing so that the cable engages the sheave substantially axially of the housing and passes under the sheave;

a second sheave mounted on the upper portion of the housing and engaging the cable to guide the cable into a path extending down the side of the housing to the fastening means.

45 13. A diesel pilehammer as defined in claim 11 wherein the lifting mechanism further comprises:

a latching means operatively connected to the rod;

an abutment formed on the housing for cooperation with the latching means to normally secure the rod in its down position and to cause an upward force applied by the cable to the lifting means to position the entire pilehammer.

14. A diesel pilehammer as defined in claim 11 wherein the lifting means further comprises:

a cushioning means to stop the descent of the lifting rod after the lifting mechanism is released and to prevent the rod from rebounding to a position that would interfere with the descent of the piston.

15. The method of operating a diesel pilehammer including a reciprocating free piston comprising:

igniting a compressed fuel-air mixture in a confined space underlying the piston to cause the piston to rise;

evacuating a space, separate from the space underlying the piston, during the rise of the piston;

permitting gases to flow to the evacuated space from the space underlying the piston and admitting air into the latter space for the scavenging thereof during the rise of the piston;

reversing the direction of movement of the piston due to a reversal of the imbalance of the forces acting thereon;

forcing the gases in the previously evacuated space to flow to the atmosphere during the descent of the piston;

confining and compressing air in the space underlying the piston during the descent of the piston; and

injecting fuel into the compressed air prior to igniting the mixture.

16. The method of operating a diesel pilehammer including a reciprocating free piston as defined in claim 15 further comprising:

confining and compressing gases in a space during the rise of the piston to assist the reversal of the imbalance of force and to shorten the distance the piston rises for increasing the cyclic rate.

17. The method of operating a diesel pilehammer including a reciprocating free piston as defined in claim 15 further comprising:

preventing gases from flowing to the space underlying the piston from the evacuated space during the descent of the piston to prevent the return of scavenged gases to the space underlying the piston.

18. The method of operating a diesel pilehammer including a reciprocating free piston as defined in claim 16 further comprising:

permitting air to flow into the last mentioned space when the piston approaches its downward most position to replenish any escaped gases.

19. The method of operating a diesel pilehammer including a reciprocating free piston as defined in claim 16 further comprising:

permitting fluid communication between the last mentioned space and the evacuated space when the piston approaches its downward most position to equalize the pressure therebetween.

20. A diesel pilehammer including a housing, a reciprocating free piston, and means for lifting the piston wherein the lifting means comprises:

a downwardly facing surface formed on the piston;

a lifting mechanism mounted on the housing and movable in a direction parallel to the reciprocation of the piston, the lifting mechanism having a portion for engaging the downwardly facing surface to raise the piston to its starting position;

means associated with the lifting mechanism for applying a lifting force thereto to raise the piston and for releasing the lifting mechanism to allow the mechanism to descend to its original position and to permit the piston to descend for starting the diesel cycle;

a cable interconnecting the lifting mechanism and the force applying means;

means for fastening the cable to the lifting mechanism;

means associated with the lifting mechanism and cooperating with a portion of the housing for automatically, releasably latching the lifting mechanism in its normal lowermost position to cause an upward force applied through the cable to the lifting mechanismto be imparted directly to the housing for positioning of the entire pilehammer; and

21. A diesel pilehammer as defined in claim 20 wherein the guide means comprises:

a sheave mounted on the upper portion of the housing so that the cable engages the sheave substantially axially of the housing and passes under the sheave; and

22. A diesel pilehammer as defined in claim 20 wherein the lifting means further comprises a cushion means for stopping the descent of the lifting mechanism after the release thereof to prevent the mechanism from rebounding to a position of interference with the descent of the piston.

References Cited UNITED STATES PATENTS 2,093,634 9/1937 Cordes 173-137 2,804,856 9/1957 Spurlin 173-135 2,882,690 4/1959 Frederick 173-134 3,303,892 2/1967 Nishimura et al 173-135 JAMES A. LEPPINK, Primary Examiner. 173-137