Abstract:
There is provided a locking mechanism to secure a coupler&#39;s jaw, and a coupler incorporating the locking mechanism.

Description:
[0001]    PRIORITY CLAIM 
         [0002]    This application is a Divisional Patent Application claiming priority from U.S. National Stage Application No. 13/499,046 filed on Mar. 29, 2012, which claims the benefit of priority under 35 U.S.C. 371 from International Patent Application No. PCT/NZ2010/000192 filed Sep. 29, 2010, which claims the benefit of priority from New Zealand Patent Application Ser. No. 579987 filed Sep. 29, 2009, the entire contents of which are herein incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0003]    The present invention relates to a coupler. 
         [0004]    BACKGROUND ART 
         [0005]    A coupler is a device used to secure a work attachment to a work vehicle. They generally have jaws that receive pins on the work attachment. 
         [0006]    At least one of the jaws is moved by an actuator. This allows the jaws to engage and release the pins thereby securing and releasing the work attachment to the coupler as required. 
         [0007]    The actuator applies a driving or engagement force to the moveable jaw to retain the pin therein. Generally another jaw of the coupler faces in the opposite direction to the moveable jaw. Therefore the driving/engagement force of the actuator also forces another pin on the work attachment into another jaw of the coupler. 
         [0008]    However, if the actuator fails then the moveable jaw can move and release the pin. This is referred to as lack of engagement force and provides a significant health and safety risk. There have been a number of recent high profile accidents involving failures such as this causing injury to people. 
         [0009]    Lack of engagement force is caused by failure of an actuator. This can be for several reasons including loss of hydraulic pressure through leaks or other damage. 
         [0010]    Therefore, it is known to have locking systems to secure a moveable jaw. These protect against failure of actuators by securing the moveable jaw with respect to the coupler to retain the pin in the jaw. 
         [0011]    One example of these devices is that disclosed in PCT Application No. GB/2007/003324 to Miller UK Limited. 
         [0012]    This coupler has a main body to support a pivotal locking member. The locking member prevents a pivoting jaw from moving should the actuator fail. This is achieved by gravity biasing the locking member downwards so that it abuts the jaw thereby holding this and preventing release of the pin. 
         [0013]    The locking mechanism of the Miller coupler can be released by moving the coupler through a number of steps. These steps involve inverting the coupler so that gravity causes the member to pivot away from the jaw. This allows the jaw to be retracted by the actuator. 
         [0014]    However, it is an inherent problem of this type of coupler that this must be inverted to enable the jaw to release the pin. This means that it can be a time consuming and awkward process to release the work attachment from the coupler. 
         [0015]    In addition, relying on gravity to move the locking member means that the system is not fail safe. For instance, dirt or debris may hinder movement of the locking member and prevent securing and/or releasing the jaw. 
         [0016]    Yet a further failing of the available couplers is that they are generally configured to work attachments having a predetermined pin separation. Therefore the couplers are not able to be used with different work attachments where the pin spacing varies. This can be a significant limitation on the available couplers. 
         [0017]    An additional limitation to the effectiveness of similar devices is that they are designed specifically for use with a fixed coupler. Many modern couplers now incorporate a tilting section which permits the attachment to be angled up to  90  degrees in each direction. Any angle less than perpendicular will reduce the effectiveness of a gravity operated locking member. Therefore, it would be advantageous to have a locking mechanism to secure a jaw with respect to a coupler to ensure that a pin is retained therein. 
         [0018]    In addition, it would be advantageous to have a coupler which addresses the issues with the prior art. 
         [0019]    Alternatively it is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice. 
         [0020]    All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country. 
         [0021]    Throughout this specification, the word “comprise”, or variations thereof such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. 
         [0022]    Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only. 
       DISCLOSURE OF THE INVENTION 
       [0023]    According to one aspect of the present invention, there is provided a coupler, including:
       a body,   a jaw to receive a pin of a work attachment and thereby secure the work attachment   to the coupler,   an actuator to move the jaw with respect to the body, and   a locking mechanism to secure the jaw with respect to the work attachment,   characterised in that the actuator moves the locking mechanism to a release position prior to moving the jaw.       
 
         [0030]    According to another aspect of the present invention, there is provided a method of securing a work attachment to a coupler, including the steps of:
       (a) using an actuator to move a jaw of the coupler so as to engage a pin on the work attachment;   (b) using a locking mechanism to secure the jaw with respect to the body;   (c) causing the actuator to move the jaw; the method characterized by the step of   (d) moving the actuator to the locking mechanism so as to move the locking mechanism to a release position prior to it moving the jaw at step (c).       
 
         [0035]    According to another aspect of the present invention, there is provided a coupler, including:
       a body,   a jaw to receive a pin of a work attachment and thereby secure the work attachment to the coupler,   an actuator to move the jaw with respect to the body, and   a locking mechanism to secure the jaw with respect to the work attachment,   characterised in that the locking mechanism secures the jaw with respect to the work attachment to prevent movement of the jaw in the case of loss of engagement force in the actuator.       
 
         [0041]    In a preferred embodiment the present invention may be incorporated to the improved coupler subject of the applicant&#39;s co-pending New Zealand Patent Application No. 572477. However, this should not be seen as limiting and the present invention can be incorporated into other couplers. 
         [0042]    In a particularly preferred embodiment the present invention is used with the “primary jaw” of a coupler and reference will be made herein. 
         [0043]    The term “primary jaw” is a term of the art generally understood as referring to a moveable jaw of a coupler. This should be understood by those skilled in the art. 
         [0044]    Preferably, the machine may be an excavator or other construction vehicle. Reference herein will be made to the machine as an excavator. 
         [0045]    However, the present invention can be used with other types of machines where releasable work attachments are utilised, including graders and bulldozers, loaders, tractors, and scrapers. 
         [0046]    Throughout the present specification, reference to the term “work attachment” should be understood as meaning an implement for performing a task. 
         [0047]    Work attachments generally include two or more pins engaged by the coupler&#39;s jaws. That engagement secures the work attachment to the machine. 
         [0048]    In a preferred embodiment the work attachment may be a digger bucket as should be known to those skilled in the art. 
         [0049]    Alternatives for the work attachment include vibration compactors, and grapples used in the forestry industry for grasping and manipulating logs, hole boring augers, clamps, rotating buckets, work platforms, mowers, and hedge cutters. 
         [0050]    However the foregoing should not be seen as limiting and alternatives are envisaged. These include graders and bulldozers, loaders, tractors, and scrapers. 
         [0051]    Throughout the present specification reference to the term “coupler” should be understood as meaning an assembly to secure a work attachment to an excavator. This should be known to those skilled in the art. 
         [0052]    In a preferred embodiment the coupler has two jaws facing in opposite directions. However it is also envisaged that the jaws could face in the same direction. The jaws will be discussed in more detail below. 
         [0053]    In a preferred embodiment the coupler may have a body to hold and/or support the components of the coupler. 
         [0054]    In a preferred embodiment the body may be moveably mounted to an excavator arm. This may occur using techniques or components as should be known to those skilled in the art including a quick hitch. 
         [0055]    In a preferred embodiment the body may include a path to allow movement of the jaw with respect to the body. The path may be a channel and/or cavity through which the jaw can move. This aspect should become clearer from the following description. 
         [0056]    However, the foregoing should not be seen as limiting and alternatives are envisaged. These include embodiments where the body does not include a path where the jaw is external to the body. 
         [0057]    Throughout the present specification reference to the term “jaw” should be understood as meaning a component to engage the pin of a work attachment. This should be known to those skilled in the art. 
         [0058]    In a preferred embodiment one of the jaws is moveable with respect to the body while one of the jaws is formed in the body. 
         [0059]    In a particularly preferred embodiment, the moveable jaw may be formed in, or attached to, a slide. In this embodiment the slide moves within the path in the body. 
         [0060]    However alternatives are envisaged including a pivoting jaw, or a jaw external to the body. 
         [0061]    Throughout the present specification reference to the term “actuator” should be understood as meaning a component that can move the jaw with respect to the body. 
         [0062]    In a preferred embodiment the actuator may be a hydraulic cylinder as should be known to those skilled in the art. 
         [0063]    However, the actuator may also be a pneumatic cylinder, a helical actuator, a threaded manual actuator, or chain drive assemblies. Therefore, the foregoing should not be seen as limiting. 
         [0064]    In a particularly preferred embodiment the hydraulic cylinder may be connected to the locking mechanism such that deliberate movement of the actuator moves the locking mechanism to a release position. This allows the actuator to move the jaw with respect to the body. This should become clearer from the following description. 
         [0065]    Throughout the present specification reference to the term “locking mechanism” should be understood as referring to a component to secure the jaw with respect to the body. 
         [0066]    In a preferred embodiment, the locking mechanism may help to ensure that a pin is sufficiently held within the moveable jaw so that the work attachment does not disengage from the coupler in the case of loss of engagement force in the actuator. However in normal operation as the actuator moves the jaw, it moves the locking mechanism to the release position thereby allowing the jaw to move so as to release the pin. 
         [0067]    In a particularly preferred embodiment the actuator is connected or linked to, the locking mechanism. That connection or link helps to ensure that the locking mechanism does not move to a release position until there is deliberate movement of the actuator. 
         [0068]    The term “deliberate movement” refers to movement intended by the excavator operator. 
         [0069]    Preferably the connection of the locking mechanism and actuator is such that the actuator can move slightly without moving the locking mechanism to the release position. This ensures that if the actuator contracts (or expands) due to loss of engagement force that it will not move the locking mechanism to the release position. 
         [0070]    However, in the preferred embodiment deliberate movement of the actuator can still move the locking mechanism to the release position thereby allowing the jaw to move. 
         [0071]    This feature is useful in protecting against loss of engagement force which would otherwise result in the jaw releasing the pin causing the work attachment to disengage. 
         [0072]    In a preferred embodiment the locking mechanism is formed from member(s) and/or pawls which engage with recess(es). 
         [0073]    In a particularly preferred embodiment, the member(s) and/or pawls are pivotally mounted to the jaw or body. The member(s) can therefore extend into the recess(es) on the body or jaw, thereby securing the jaw with respect to the body. 
         [0074]    In a particularly preferred embodiment the locking member(s) and/or pawls are biased into a locking position. This may be achieved using biasing elements such as springs or compressible material detents. These components apply an urging force to the locking member(s) forcing these towards the recesses. Therefore once the pawls and/or locking members align with the recess they engage. 
         [0075]    However this should not be seen as limiting as alternatives are envisaged. 
         [0076]    In a particularly preferred embodiment the locking mechanism may be multi-centred. 
         [0077]    The term “multi-centred” should be understood as meaning that the locking mechanism can function with variations in pin spacing on work attachments. 
         [0078]    For instance, the locking mechanism can secure the jaw at different positions along the length of the path. 
         [0079]    In a preferred embodiment this may be achieved by having multiple recess(s) along the length of the path. The member(s) and/or pawls engage the recess(es) to secure the jaw. 
         [0080]    This is advantageous as it allows the locking mechanism to operate with different work attachments which may have pins positioned at different spacings. 
         [0081]    However the foregoing should not be seen as limiting and alternatives are envisaged. Those include a different mechanism for providing a multi-centred locking mechanism, or couplers that do not have multi-centred locking mechanisms. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0082]    Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which: 
           [0083]      FIG. 1  is an end perspective view of a slide according to the present invention. 
           [0084]      FIG. 2A  is a side perspective view of a coupler according to the present invention having a locking mechanism in a release position. 
           [0085]      FIG. 2B  is a side view of a coupler according to the present invention having a locking mechanism in the locking position. 
           [0086]      FIG. 3  is an exploded view showing components of the present invention. 
           [0087]      FIG. 4  is a side view of a locking member. 
           [0088]      FIGS. 5A-D  show a side cross sectional view of an alternate embodiment in operation. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0089]    The present invention provides an improved coupler  1 . The aspects of the coupler  1  will be described by reference to its components in the order in which they are assembled. 
         [0090]    A body  2  houses the components of the coupler  1 . The body  2  has side walls and end walls  4 . The walls  3 ,  4  define a cavity  5  to receive a slide  6 . 
         [0091]    Flanges  7 ,  8  on the body  2  have apertures  9 ,  10  forming part of a quick hitch (not shown). The quick hitch facilitates securing the coupler  1  to an excavator (not shown). This should be understood by those skilled in the art. 
         [0092]    A first end  11  of the body  2  is formed to provide a first jaw  12 . The first jaw  12  may include a locking system to secure a pin therein. The locking system is not shown in order to simplify the Figures. However it could be any known or yet to be developed locking system. 
         [0093]    A second end  13  of the body  2  has an aperture  14  into the cavity  5 . 
         [0094]    The inside of side walls  2  have channels  15  one of which is shown in  FIGS. 2A and 2B . Each channel  15  has a top surface  16  and a bottom surface  17 . 
         [0095]    A row of recesses  18 ,  19 ,  20  in the bottom surface  17  are spaced apart along the length of the channel  15 . Recesses  18 ,  19 ,  20  provide a multi centred locking mechanism as should become clearer from the following description. 
         [0096]    The channels  15  define an axis of movement for the slide  6  allowing this to move forward and backwards freely. The axis of movement is shown as line Y. 
         [0097]    The slide  6  has a jaw  21 . The jaw  21  is the primary jaw of the coupler  1  as should be known to those skilled in the art. 
         [0098]    Slide  6  has guide portions  22 . The guide portions  22  have a shape corresponding to channels  15 . Therefore the guide portions  22  may be disposed in the channels  15 . It should be appreciated that the channels  15  define a path to guide movement of the slide  6 . 
         [0099]    The slide  6  has slot apertures  23 . The slot apertures  23  can receive a connection pin  24 . 
         [0100]    Locking members  25  are pivotally attached to the slide  6  at points  26 . The locking members  25  are shown in  FIG. 4 . 
         [0101]    The locking members  25  have a connector aperture  26 . The axis of the connector aperture is shown as line X. Axis x is at a  45  degree angle to axis of movement Y. 
         [0102]    The locking members  2  have a nub  27 . The nub  27  provides a locking edge shown by line  28 , and a leading edge shown by line  29 . 
         [0103]    The leading edge  29  is shaped so that it does not hinder movement of the slide  6  towards the second end  13 . The locking edge  28  is shaped so that it stops the slide  6  moving towards end  11  when in the locking position. This should become clearer form the following description. 
         [0104]    Biasing elements  30  urge the locking members  25  to pivot around points  31 . The biasing elements  30  may be springs or rubber detents. 
         [0105]    Connection pin  24  extends through the slot apertures  23  and connection apertures  26 . 
         [0106]    An actuator  32  in the form of a hydraulic cylinder is positioned inside the cavity  5 . 
         [0107]    The actuator  32  is connected to a control system (not shown). The control system allows a user to control extension or contraction of the actuator  32 . 
         [0108]    End  33  of the actuator  32  is secured to the body  2 . End  34  of the actuator  32  is connected to the connection pin  24 . 
         [0109]    The slide  6  has slot apertures  23 . The slot apertures  23  are approximately 20% longer than the diameter of the connection pin  24 . This provides slack in the connection of the actuator  32  to the locking members  25 . 
         [0110]    Extension of the actuator  32  moves the slide  6  forward towards second end  13 . This will be referred to herein as locking movement. 
         [0111]    Contraction of the actuator  32  moves the slide  6  towards first end  11 . This will be referred to herein as releasing movement. 
         [0112]    The operation of the coupler  1  will now be described with reference to  FIGS. 2A and 2B . 
         [0113]    The jaw  12  engages a first pin  36 A on a work attachment (neither shown in  FIGS. 2A or 2B ). The coupler  1  is rotated about the pin. 
         [0114]    The actuator  32  extends to move the slide  6  forward towards end  13 . Biasing elements  30  urge locking members  25  towards a locking position. However, the leading edge  29  does not hinder movement of the slide  6  towards end  13 . 
         [0115]    Movement of the slide  6  continues until the jaw  21  engages pin  36  on a work attachment (not shown). This secures the work attachment to the coupler  1 . 
         [0116]    At this position the locking members  25  do not engage any of the recesses  18 ,  19 ,  20 . 
         [0117]    The actuator  32  applies a driving or engagement force that ensures that the jaw  12  engages the pin  36 B. 
         [0118]    The position of the recesses  18 ,  19 ,  20  is selected so that these correspond to the positions in which the jaw  21  engages a pin. That is, when the jaw  12  engages a pin  36 B the locking members  25  are adjacent to one of the recesses  18 ,  19 ,  20 . 
         [0119]    Note that when the jaw  21  engages pin  36 B the nubs  27  do not align with a recess  18 ,  19 ,  20 . 
         [0120]    The work attachment can be used as per normal operation. 
         [0121]    If the actuator  32  loses hydraulic pressure the slide  6 , and therefore jaw  21 , moves along the length of the channels  15  towards end  11 . However, this aligns nubs  27  with one of the recesses  18 ,  19 ,  20 . 
         [0122]    The biasing elements  30  urge the locking members  25  to pivot and thereby force nubs  27  into one of the recesses  18 ,  19 ,  20 . In the embodiment shown in  FIG. 2B  this is recess  18 . This is the locking position. 
         [0123]    The locking members  25  secure the slide  6  with respect to the body  2 . This protects against loss of engagement force due to failure of the actuator  32 . 
         [0124]    The connection of the actuator  32  to the slide  6  is such that the locking mechanism secures the slide  6  with respect to the body  2  until deliberate movement of the actuator  32  moves the locking members  25  to the release position. That is, to release the pin  36 B from the jaw  21  an operator sends a signal to the actuator  32  to contract. The actuator  32  moves the connection pin  24  along the length of the slot apertures  23  towards end  11 . The connection pin  24  presses against the edges of the connector apertures  26 . The incline of the connector apertures  26  causes the connection pin  24  to move the locking members  25  thereby drawing the nubs  27  out of recesses  18  and moving the locking members  25  into the release position. 
         [0125]    In the release position the slide  6  can move with respect to the body  2  to release the pin  36  and thereby release the work attachment from the coupler  1 . 
         [0126]    It should be appreciated that the use of multiple recesses  18  which are spaced along the channels  15  allows the locking mechanism to secure the slide  6  jaws  21 . This may be beneficial where the coupler  1  is used with work attachments (not shown) having pins  36 A,  36 B of different spacing. Therefore, were the actuator  32  to fail then the recesses may facilitate a locking member  25  preventing the jaw  12  releasing the pin. Therefore, the coupler  1  and locking mechanism guard against loss of engagement force and may facilitate a coupler being used with different types of, or specification, work implements. 
         [0127]    Referring now to  FIGS. 5A-E  showing an alternate embodiment of the coupler  1 . Like numerals are used to refer to like components from  FIGS. 1-4 . 
         [0128]    The components of the coupler  1  are identical to that shown and discussed with reference to  FIGS. 1-4 . However, the orientation of the locking members  25  and recesses  18 ,  19 ,  20  has been altered. That is, the recesses  18 ,  19 ,  20  are now in the top surface  16  of the channel  15 . 
         [0129]    The nubs  27  now face upwards towards top surface  16 . The biasing elements  30  urge the locking members  25  to pivot upwards with respect to the slide  6  at points  26 . In all other aspects the operation of the coupler shown in  FIGS. 5A-E  is identical to that shown in  FIGS. 1-4 . 
         [0130]      FIG. 5A  shows the coupler  1  having the actuator  32  fully contracted. This moves slide  6  so as jaw  21  releases pin  36 B. Note that locking member  25  is rotated so that nub  27  does not engage or extend into one of the recesses  18 ,  19 ,  20 . 
         [0131]      FIG. 5B  shows the actuator  32  partly through its stroke. The jaw  21  is moved towards pin  36 B. 
         [0132]    Continued extension of the actuator  32  causes the jaw  21  to engage the pin  36 B as shown in  FIG. 5C . Note that locking members  25  have been moved past recesses  18 ,  19 ,  20 . Nub  27  does not align with, nor extend into, any of recesses  18 ,  19 ,  20 . 
         [0133]    If loss of engagement force occurs through failure of actuator  32  slide  6  can move with respect to body  2 . This is shown in  FIG. 5C . Note that locking member  25  has been moved along the length of path  15  so as nubs  27  align with recess  18 . 
         [0134]    Biasing elements  30  force locking members  25  so as to pivot upwards towards top surface  16 . This causes nubs  27  to extend into recesses  18 . The locking member  25  prevents the slide  6  moving further towards end  2 . Therefore, the jaw  21  does not fully release pin  36 B. Accordingly, the locking mechanism prevents the coupler from releasing the work attachment. 
         [0135]    Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.