GB2517673A

GB2517673A - Improved actuator for couplers

Info

Publication number: GB2517673A
Application number: GB1308493.4A
Authority: GB
Inventors: Ian Hill
Original assignee: HILTEC DESIGNS Ltd
Current assignee: HILTEC DESIGNS Ltd
Priority date: 2013-05-12
Filing date: 2013-05-12
Publication date: 2015-03-04
Anticipated expiration: 2033-05-12
Also published as: GB201308493D0; GB2517673B

Abstract

A coupler for coupling an attachment to an excavator has a latching member operated by an actuator assembly comprising an actuator 132 and a hydraulic block, a pair of trunnions 160 projecting from the block 152. The actuator comprises a piston housing defining a piston chamber. The piston chamber houses a piston head and a piston rod, the block being located at an end of the housing, and includes a cavity 158 containing a portion of the piston chamber. As a result, the height of the hydraulic block is reduced and the length of the ram assembly can be shorter.

Description

Improved Actuator for Couplers

Field of the Invention

The present invention relates to actuators for couplers. The invention relates particularly to hydraulic rams for couplers for coupling an attachment, such as an excavating bucket, to the arm of an excavator or other machine.

Background to the Invention

Hydraulic couplers for quickly connecting and disconnecting construction attachments from excavating equipment are well known and are sometimes referred to as automatic or quick couplers since they can be operated by an operator from with the cab of an excavator or other machine. International POT patent application W0201 1/035883 discloses an example of such a coupler.

Quick couplers suffer from a problem, especially when used in conjunction with buckets, in that the distance from the pivot point on the excavator arm (the dipper pin) to the end of the tooth of the bucket is increased by the height of the coupler. This leads to a loss of breakout force due to the decreased moment at the tip of the tooth. Accordingly, the height of the coupler is an important design consideration. A significant portion of a coupler's height is due to the space requirement for a cylinder block, the block being part of a ram that operates the coupler's latch. In addition the coupler's height is affected by the length of the cylinder. When the height of a coupler is reduced the cylinder must be flatter (less inclined) with respect to the body of the coupler, which increases its effective length.

Summary of the Invention

A first aspect of the invention provides a coupler as claimed in claim 1.

A second aspect of the invention provides an actuator assembly as claimed in claim 12.

Preferred features are recited in the dependent claims.

Preferred features of the preferred embodiments have the effect, individually and in combination, of reducing the height of the hydraulic block in comparison to a conventional block, and allow the length of the ram assembly to be less that for a conventional assembly. As a result, the device into which the ram assembly is incorporated in use requires less space to accommodate the ram assembly than would be required for a conventional ram assembly.

Further advantageous aspects of the invention will be apparent to a skilled person upon review of the following description of a preferred embodiment and with reference to the accompanying drawings.

Brief Description of the Drawings

An embodiment of the invention is now described by way of example and with reference to the accompanying drawings in which like numerals are used to denote like parts and in which: Figure 1 is a side view of a conventional coupler with a conventional hydraulic actuator; Figure 2 is a side view of a coupler embodying one aspect of the invention with a hydraulic actuator embodying another aspect of the invention; Figure 3 is a perspective view of part of the actuator of Figure 1; Figure 4 is a sectioned side view of the actuator of Figure 1; Figure 5 is a perspective view of pad of the actuator of Figure 2; and Figure 6 is a sectioned side view of the actuator of Figure 2;

Detailed Description of the Drawings

Referring now to Figures 1 and 2 of the drawings there is shown, generally indicated as 10, 110, a respective coupler (or hitch) for connecting a tool, or other attachment such as a bucket or hammer, to an arm 9 of an excavator (not shown), or other apparatus. The coupler 10, 110 has a body 14 typically comprising two spaced-apart body parts typically in the form of side plates 15 (only one shown). The body 14 is shaped to define pin-receiving apertures 16, 17 by which the coupler 10, 110 may be connected to the end of the arm. Typically, there are two spaced-apart apertures 16, 17 in each of the two side plates, the apertures in one side plate being aligned with the apertures in the other.

When connected, the coupler 10, 110 is able to pivot with respect to the arm about the axis of the aperture 17. Usually a hydraulic mechanism, or other power operated mechanism (not shown), is provided, typically in association with a mechanical linkage, to pivot the coupler 10, 110 with respect to the arm. The mechanical linkage is usually connected between the arm and the aperture 16.

The body 14 includes first and second pin-receiving recesses 20, 22 formed in each side plate 15. Each recess 20, 22 is shaped and dimensioned to receive a respective pin (not shown) of a bucket or other attachment. Normally, the recesses 20, 22 face in mutually perpendicular directions. The recess 20 is typically hook-like in shape and function. The recess 22 may be wider than is necessary to receive a single pin in order to accommodate attachments with different pin spacings.

The coupler 10, 110 also include a power-operated latching mechanism typically comprising a latching member, in the preferred form of a hook 30, and an actuator 32, 132 typically in the form of a linear actuator, usually a hydraulic ram. Other forms of powered actuator could be used (e.g. pneumatic or electrically operated) but hydraulic is convenient because excavators typically have a hydraulic system available at or near the end of the arm. The coupler 10 has a conventional hydraulic ram 32, while the coupler has a ram 132 embodying one aspect of the present invention. The latching hook 30 and ram 32, 132 are provided between the side plates 15. The latching hook 30, which may comprise one or more aligned hook elements, is pivotably mounted on the body 14 at pivot 11 in any convenient manner and is pivotable about an axis that runs substantially perpendicular to the body 14/plates 15. The hook 30 is pivotable between an open, or non-latching, state and a latching state. In the open state, the latching hook allows attachment pins to be inserted into or removed from the recess 22. In the latching state, the latching hook 30 prevents the pins from being removed from the recess 22. In alternative embodiments, the latching member may be slidably mounted on the body, or otherwise movable between the open state and the latching state(s), without necessarily being pivotable. Further, the latching member need not necessarily take the form of a hook. Conventionally, the recess 22 is said to be at the rear of the coupler and the latching member 30 may therefore be referred to as a rear latching member.

The couplers 10, 110 may be referred to as an automatic couplers, or a power operated coupler, and are exemplary of the general type of coupler with which embodiments of the invention may be implemented but it will be understood that the invention is not limited to use with the specific couplers shown in Figures 1 and 2.

Referring now in particular to Figures 1, 3 and 4, the conventional ram 32 has a piston housing 40, which is commonly referred to as a cylinder, defining a piston chamber 42 for a piston head 44. The piston head 44 is connected to a piston rod 46. The piston head 44 and piston rod 46 are together capable of reciprocating movement with respect to the housing 40 (as indicated by arrow A) as the ram 32 is operated between a retracted state (illustrated) and an extended state (not illustrated). The illustrated ram 32 is a double acting ram. A fluid port 48 is provided in the housing 40 to let hydraulic fluid, typically oil, into and out of the chamber 42 via fluid line 49. Fluid line 49 is internally connected within the block 52 such that it is in fluid communication with external connection 64. In addition chamber 42A is in fluid communication with external connection 63 via internal channel(s) the block (not shown). In use, pressurized hydraulic fluid is supplied to external port 63 and thus to the chamber 42A at the rear (with respect to the rod) of the piston head 44 to cause the head 44 to move and the rod 46 to extend, and oil is forced from chamber 42 which then flows from port 64 via port 48, fluid line 49 and the internal channel(s) in the block (not shown).

Alternatively pressurized hydraulic fluid is supplied to external port 64 and thus to the chamber 42 at the front (with respect to the rod) of the piston head 44 via the internal porting of the block, fluid line 49 and port 48 to cause the head 44 to move and the rod 48 to retract, forcing oil from chamber 42A which then flows from port 63 via the internal porting of the block (not shown).

A block 52 (sometimes referred to as a cylinder block) is provided at the butt end 54 of the ram 32, i.e. the end opposite the piston rod end. The block 52 may include one or more hydraulic circuit components, e.g. fluid channel(s) and/or valve(s) (typically including a pilot operated check valve which requires space within the block that accounts for a proportionally increasing amount as cylinders become smaller), and conventionally also includes a through-hole 54 for receiving a mounting pin (not shown) by which the ram 32 may be pivotably mounted to the coupler 10. The block 52 does not substantially overlap with the housing in the longitudinal direction of the ram 32 and, as such contributes significantly to the length of the assembly of which the ram 32 is part. The block 52 also contributes significantly to the height of the ram assembly.

Referring now in particular to Figures 2, 5 and 6, the ram 132 is described in more detail.

The ram 132 has a piston housing 140, which is commonly referred to as a cylinder, defining a piston chamber 142/l42Afora piston head 144. The piston head 144 is connected to a piston rod 146. The piston head 144 and piston rod 146 are together capable of reciprocating movement with respect to the housing 140 (as indicated by arrow A) as the ram 132 is operated between a retracted state (illustrated) and an extended state (not illustrated). The illustrated ram 132 is a double-acting ram and has a fluid port 148 in the housing for allowing hydraulic fluid, typically oil, to flow into and out of the chamber 142 at one side of the piston head 144 to external connection 164 via passage 156, external pipe 159, port 162 and internal porting (channel(s)) of the block (not shown). In addition it also has a respective fluid port (not shown) in the housing for allowing hydraulic fluid, typically oil, to flow into and out of the chamber portion 142A at the opposite side of the piston head 144 to external connection 163 via internal porting of the block (not shown). In use, when pressurized hydraulic fluid is fed into the chamber 142 by port 148 from external port 164, pressure on the front face of the head 144 causes it to move (right to left as viewed in Figure 6) and hydraulic fluid to leave the chamber portion 142A via its respective port and thus to external port 163 via the internal porting of the block (not shown). Hence the rod 146 retracts. When pressurized hydraulic fluid is fed into the chamber portion 142A from external connection 163 via internal porting (channel(s)) of the block (not shown) pressure on the rear face of the head 144 causes it to move (left to right as viewed in Figure 6) and hydraulic fluid to leave the chamber 142 via port 148 and to external port 164. Hence the rod 146 extends. . The fluid line 156 is advantageously provided on or in the housing 140, typically running longitudinally of the housing 140. In alternative embodiments (not illustrated) the rain 132 may be a single acting ram, the housing having a single fluid port at one side of the piston head 144, and a return spring.

A block 152 (which may be referred to as a cylinder block or a hydraulic block) is provided at the butt (or rear) end 154 of the ram 132, i.e. the end opposite the end from which the piston rod emerges. The ram 132 and block 152 may together be said to form a ram assembly (or more generally an actuator assembly). The block 152 typically includes one or more hydraulic circuit components, e.g. fluid channel(s), port(s) and/or valve(s), typically including a pilot operated check valve (not shown) and/or a ball valve (not shown), at least some of which are located inside the block 152 in one or more respective cavities or channels. The block 152 is shaped to define a cavity 158 for receiving the butt end 154 of the housing 140. The cavity 158 is sufficiently deep that the block 152 and the piston chamber 142 overlap in the longitudinal direction of the ram 132. Preferably the amount of the overlap is such that the piston head 144 is at least partially, and preferably fully, located with the block 152 when in its retracted state (in particular at least when it is in its most retracted position in the chamber 142). Advantageously, the cavity 158 is substantially centrally located in the block 152.

In preferred embodiments, the provision of cavity 158 is facilitated by the absence of a through-hole for receiving a mounting pin. For mounting the ram 132 (and block 152) on the coupler 110 (or other device) it is preferred to provide a respective trunnion 160 (only one visible) at opposite sides of the block 152, each trunnion typically projecting from the block 152 in opposite directions each of which is substantially perpendicular to the longitudinal axis of the ram 132. The coupler 110, or other device, includes corresponding female couplings (not shown), e.g. a respective socket, seat or track, to allow the ram assembly to be coupled to the coupler/other device for pivoting, sliding or other movement with respect thereto as required by the application.

It will be seen from the foregoing that the omission of the through-hole from the block 152 allows a higher proportion of the block 152 to be used for housing or providing hydraulic circuit components (such as channels, ports and valves), and allows the housing 140, and in particular the piston chamber 142, to be recessed into the block 152. These features have the effect, individually and in combination, of reducing the height of the block 152 in comparison to a conventional block, and allow the length of the ram assembly to be less that for a conventional assembly. As a result, the device into which the ram assembly is incorporated in use requires less space to accommodate the ram assembly than would be required for a conventional ram assembly. This is illustrated in the context of couplers 10, 110 with reference to Figures 1 and 2 from which it may be seen that a height Hi of the coupler 10 with conventional ram assembly is more than the corresponding height H2 of the coupler 110 with the ram assembly 132.

The invention is not limited to the embodiments described herein which may be modified or varied without departing from the scope of the invention.

Claims

CLAIMS: 1. A coupler for coupling an attachment to an excavator or other apparatus, the coupler comprising a body having a first and second spaced-apart recesses for receiving respective pins of said attachment; a latching member movable into and out of a latching state in which it is capable of retaining the respective attachment pin in said first recess; and actuating means for actuating said latching member into and out of said latching state, wherein said actuating means comprises an actuator assembly comprising an actuator and a block, the actuator comprising a piston housing shaped to define a piston chamber, the piston chamber housing a piston head and a piston rod, wherein said block is located at an end of said housing and includes a cavity containing a portion of said piston chamber, and wherein at least one trunnion projects from said block.
2. A coupler as claimed in claim 1, wherein said actuator assembly is coupled to said coupler by interengagement of said at least one trunnion with one or more corresponding female coupling member provided on the coupler, preferably on the body of the coupler.
3. A coupler as claimed in claim 1 or 2, wherein said actuator assembly is coupled to said coupler by said at least one trunnion for pivoting movement with respect to said coupler body.
4. A coupler as claimed in claim 1 or 2, wherein said actuator assembly is coupled to said coupler by said at least one trunnion for sliding movement with respect to said coupler body.
5. A coupler as claimed in any preceding claim, wherein said cavity contains at least some of said piston head when said piston head is in a retracted position.
6. A coupler as claimed in claim 5, wherein said cavity contains all of said piston head when said piston head is in a retracted position.
7. A coupler as claimed in any preceding claim, wherein said block contains one or more hydraulic circuit components.
8. A coupler as claimed in any preceding claim, wherein said block contains one or more instances of any one or more of a valve, a fluid channel, a fluid port or a component cavity.
9. A coupler as claimed in any preceding claim, wherein said at least one trunnion comprises a respective trunnion located at opposite sides of the block.
10. A coupler as claimed in any preceding claim, wherein said at least one trunnion projects from said block in a direction substantially perpendicular with the longitudinal axis of the housing.
11. A coupler as claimed in any preceding claim, wherein said actuator comprises a hydraulic ram.
12. An actuator assembly comprising an actuator and a block, the actuator comprising a piston housing shaped to define a piston chamber, the piston chamber housing a piston head and a piston rod, wherein said block is located at an end of said housing and includes a cavity containing a portion of said piston chamber, and wherein at least one trunnion projects from said block.
13. An actuator assembly as claimed in claim 12, wherein said cavity contains at least some of said piston head when said piston head is in a retracted position.
14. An actuator assembly as claimed in claim 13, wherein said cavity contains all of said piston head when said piston head is in a retracted position.
15. An actuator assembly as claimed in any one of claims 12 to 14, wherein said block contains one or more hydraulic circuit components.
16. An actuator assembly as claimed in any one of claims 12 to 15, wherein said block contains one or more instances of any one or more of a valve, a fluid channel, a fluid port or a component cavity.
17. An actuator assembly as claimed in any one of claims 12 to 16 wherein said at least one trunnion comprises a respective trunnion located at opposite sides of the block.
18. An actuator assembly as claimed in any one of claims 12 to 17, wherein said at least one trunnion projects from said block in a direction substantially perpendicular with the longitudinal axis of the housing.
19. An actuator assembly as claimed in any one of claims 12 to 18, wherein said actuator comprises a hydraulic ram.