Abstract:
A battery operated hydraulic compression tool comprising a frame; a hydraulic fluid reservoir connected to the frame; an electric motor driven hydraulic pump connected to the hydraulic fluid reservoir; a ram movably connected to the frame; and a multi-speed ram advancement system for advancing the ram in at least two different rates of movement on the frame. The advancement system includes a rapid advance actuator located directly against the ram, and a hydraulic bypass system located between the pump and the ram for conduiting hydraulic fluid past the rapid advance actuator to the area of the frame holding the ram.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to hydraulic compression tools and, more particularly, to a hydraulic compression tool having a rapid ram advance. 
     2. Prior Art 
     U.S. Pat. No. 5,979,215 discloses a hand operated hydraulic compression tool with a rapid ram advance. A mechanical actuator pushes against a rear end of the ram to move the ram at a first rate of movement until a predetermined resistance is encountered by the ram. After resistance is encountered, the hydraulic fluid pump moves the ram at a slower second rate of movement. One disadvantage of the tool is that it is relatively large. Battery operated hydraulic compression tools are known in the art, but they do not comprise a rapid ram advance. 
     U.S. Pat. No. 5,727,417 discloses a portable battery powered crimper. The crimper has a hydraulic pump with a rotating wobble plate connected to an electric motor. The wobble plate axially rotates to reciprocate hydraulic pistons. However, the crimper does not comprise a rapid ram advance. 
     There is a desire to provide a battery operated hydraulic crimping tool which has a rapid ram advancement system to increase the speed for crimping an electrical connector onto a conductor and for allowing a rechargeable battery to perform more crimping operations before having to be recharged. There is also a desire to provide a battery operated hydraulic crimping tool which can use a relatively low volume per revolution revolving hydraulic pump (to minimize cost, weight and size), but which can nonetheless maximize crimp speed. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, a battery operated hydraulic compression tool is provided comprising a frame; a hydraulic fluid reservoir connected to the frame; an electric motor driven hydraulic pump connected to the hydraulic fluid reservoir; a ram movably connected to the frame; and a multi-speed ram advancement system for advancing the ram in at least two different rates of movement on the frame. The advancement system comprises a rapid advance actuator located directly against the ram, a suction conduit located between the hydraulic fluid reservoir and an area of the frame holding the ram; and a hydraulic bypass system located between the pump and the ram for conduiting hydraulic fluid past the rapid advance actuator to the area of the frame holding the ram. 
     In accordance with another aspect of the present invention, a battery operated hydraulic compression tool is provided comprising a frame; a hydraulic fluid reservoir connected to the frame; an electric motor driven hydraulic pump connected to the hydraulic fluid reservoir; a ram movably connected to the frame; a hydraulic fluid conduit system in the frame between the pump and the ram; and a mechanical actuator provided in the conduit system for contacting and pushing against the rear end of the ram. The conduit system is adapted to conduit hydraulic fluid from the pump against both the rear end of the ram and a rear end of the mechanical actuator. 
     In accordance with one method of the present invention, a method of advancing a ram in a hydraulic compression tool is provided comprising steps of actuating an electric motor in the tool to actuate a hydraulic pump of the tool to move the ram relative to a frame of the tool at a first rate of movement comprising hydraulic fluid pushing against a first pushing surface connected to the ram to push the ram forward; and automatically switching movement of the ram to a second slower rate of movement when the ram encounters a predetermined resistance to forward movement on the frame, wherein the step of automatically switching comprises a bypass valve in the tool opening to allow hydraulic fluid to be pumped by the pump into an area adjacent a rear end of the ram. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and other features of the present invention are explained in the following description, taken in connection with the accompanying drawings, wherein: 
     FIG. 1 is a side elevational view of a battery operated hydraulic compression tool incorporating features of the present invention; 
     FIG. 2 is a partial cross sectional view of a portion of the tool shown in FIG. 1 with the ram at a home retracted position; and 
     FIG. 3 is a partial cross sectional view as in FIG. 2 with the ram at an extended forward position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, there is shown a side elevational view of a battery operated hydraulic tool  10  incorporating features of the present invention. Although the present invention will be described with reference to the single embodiment shown in the drawings, it should be understood that the present invention can be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used. 
     The tool  10 , in the embodiment shown, is a compression tool for crimping an electrical connector onto an electrical conductor. However, in alternate embodiments, features of the present invention could be incorporated into any suitable type of hydraulic tool. The tool  10  generally comprises a frame  12 , a hydraulic fluid reservoir  14 , an electric motor  16 , a hydraulic pump  18 , a movable ram  20  and a battery  22 . 
     Referring also to FIG. 2, the frame  12  comprises a compression head section  24  and a handle section  26 . In an alternate embodiment, the frame could have any suitable number or type of sections. The battery  22  is preferably a rechargeable battery and is preferably removably connected to the handle section  26 . However, in alternate embodiments, any suitable type of battery or electrical power supply could be provided for the motor  16 . In addition, the battery might not be removable. 
     The ram  20  is movably connected to the frame  12 . A portion  28  of the frame is located directly opposite the front end of the ram  20  to function as an anvil section. The portion  28  and front end  30  of the ram  20  are preferably adapted to removably receive electrical connector crimping dies therein. However, in alternate embodiments, the portion  28  and ram  20  might be dieless crimping members. In another alternate embodiment, the portion  28  and/or the ram  20  could comprise cutting surfaces. 
     The rear end  32  of the ram  20  is located in a chamber  34  of the frame  12 . FIG. 2 shows the ram  20  in a retracted home position relative to the frame  12 . A spring  36  is provided to bias the ram  20  at its home position. The ram  20  includes a seal  38  on its rear end  32  which makes a sealing engagement with the frame  12 . The rear end  32  and seal  38  divide the chamber  34  into a front section  34   a  and a rear section  34   b.  The ram  20  is adapted to longitudinally slide relative to the frame  12  as indicated by arrow A. However, in alternate embodiments, the tool could comprise any suitable type of ram. 
     The electric motor  16  is preferably a small DC motor. However, in an alternate embodiment, the tool could comprise any suitable type of electric motor. The motor  16  is electrically connectable to the battery  22  when a user actuates a trigger switch  40 . However, in an alternate embodiment, any suitable means for actuating the motor  16  could be provided. The motor  16  is connected to the pump  18  by a coupling  42 . Coupling  42  could be a reduction gear assembly. Alternatively, the coupling  42  could be a direct coupling. 
     The hydraulic pump  18  in the embodiment shown is a fixed displacement axial piston pump. However, in alternate embodiments, any suitable type of hydraulic pump could be used. In a preferred embodiment, the pump  18  is a cartridge style pump having an outer frame  44 , an inner frame  46 , pistons  48 , a wobble member  50  and a drive member  52 . The front end of the pump  18  is fixedly located in an area  58  of the frame  12 . A seal  60  is provided between the outer frame  44  and the frame  12 . 
     The drive member  52  extends out of the rear end of the outer frame  44  and is connected to the coupling  42 . The front end of the drive member  52  is connected to the wobble member  50 . The pistons  48  are located in channels of the inner frame  46  and extend from the rear end of the inner frame  46 . The pump includes springs  54  which bias the pistons  48  against the front face of the wobble member  50 . The inner frame  46  has a hydraulic channel outlet  56  at the front end of the outer frame  44 . 
     The pistons  48  are adapted to reciprocally move in and out of the channels of the inner frame  46 . More specifically, when the wobble member  50  is axially rotated by the motor  16 , the pistons  48  are reciprocated in forward and rearward directions. Forward movement of the pistons  48  pushes hydraulic fluid forward. Hydraulic fluid pumped forward by the pistons  48  can be pushed out of the outlet  56  into the front end of the area  58 . The seal  60  prevents the hydraulic fluid from inadvertently returning back to the reservoir  14 . 
     The hydraulic fluid reservoir  14 , in the embodiment shown, surrounds the rear end of the pump  18 . This type of coaxial design helps to keep the length of the tool  10  relatively small, thus, helping to reduce the size and weight of the tool. In a preferred embodiment, the hydraulic fluid reservoir  14  as a collapsible bladder (not shown) which can collapse as hydraulic fluid is pushed by the pump  18  out of the reservoir  14 . However, in an alternate embodiment, the tool could comprise any suitable type of hydraulic fluid reservoir. The hydraulic fluid is preferably oil, but any suitable type of hydraulic fluid could be provided. The outer frame  44  preferably has an opening  62  therein to allow hydraulic fluid to pass from the reservoir  14  into the area  64  for subsequent entry and pumping by the pistons  48 . 
     The tool  10  comprises a hydraulic fluid conduit system for delivering hydraulic fluid from the pump  18  and the reservoir  14  to the rear section  34   b  of the ram chamber  34 , and back to the reservoir  14 . In the embodiment shown, the conduit system includes the front section of the area  58 , a mechanical actuator conduit  66 , a pump bypass conduit  68 , a suction conduit  70 , and a hydraulic fluid return conduit (not shown). The hydraulic fluid return conduit extends from the rear section  34   b  of the chamber  34  back to the reservoir  14 . In a preferred embodiment, the hydraulic fluid return conduit comprises a valve (not shown) which can be moved to an open position by an user actuated member  72  (see FIG.  1 ). However, any suitable type of hydraulic pressure release mechanism could be used. 
     The tool  10  comprises a shuttle member  74  which can function as a rapid advance actuator or mechanical actuator. The actuator  74  is longitudinally slidably located in the mechanical actuator conduit  66 . Seals are provided between the actuator  74  and the frame  12  to form a seal between the area  58  and the rear section  34   b.  The actuator  74  is a separate member from the ram  20 . However, a front end of the actuator  74  is adapted to directly contact the ram  20  for allowing the actuator  74  to push the ram  20  forward as further understood below. The rear end of the actuator  74  is located at the front end of the area  58 . Thus, hydraulic fluid pumped by the pump  18  into the front end of the area  58  is in direct communication with the rear end of the actuator  74 . 
     The pump bypass conduit  68  extends from the area  58  to the section  34   b.  The pump bypass conduit  68  includes a ball  76  and spring  78  located therein to form a check valve. When hydraulic pressure in the front of the area  58  is sufficiently large enough to compress the spring  78  hydraulic fluid can flow through the conduit  68  from the area  58  to the section  34   b.  In an alternate embodiment, the bypass conduit  68  and bypass valve formed by the ball  76  and spring  78  could be formed as an assembly inside the actuator  74 . 
     The suction conduit  70  extends from the reservoir  14  to the rear section  34   b.  The suction conduit  70  includes a ball  80  and a spring  82  located therein to form a check valve. When suction or reduced pressure in the rear section  34   b  is sufficiently large enough to move the ball  80  and compress the spring  82 , hydraulic fluid from the reservoir  14  can be sucked through the suction conduit  70  directly into the rear section  34   b.  In an alternate embodiment, any suitable type of system for delivering hydraulic fluid to the rear section  34   b,  when the ram  20  is being advanced by the actuator  74  at the first rate of movement, could be provided. 
     When the ram  20  is at its home retracted position and a user depresses the trigger switch  40 , the motor  16  rotates the coupling  42  to thereby rotate the wobble member  50 . This causes the pistons  48  to move in and out relative to the inner frame  46  and thereby pump hydraulic fluid out the outlet  56  into the front of the area  58 . The hydraulic fluid presses against the rear end of the actuator  74 . The hydraulic fluid also presses against the ball  76 . However the pressure of the hydraulic fluid is insufficient to move the ball  76  away from its valve seat on the frame  12 . 
     With the hydraulic fluid pressing against the rear end of the actuator  74 , the actuator  74  is moved forward at a first rate of movement in the mechanical actuator conduit  66 . Because the actuator  74  is located against the ram  20 , movement of the actuator  74  forward directly pushes against the ram  20  and moves the ram  20  forward at the first rate of movement. As the ram  20  is moved forward by the actuator  74 , a vacuum or reduced pressure is generated in the rear section  34   b  of the chamber  34  by the forward movement of the ram&#39;s rear section  32 . This vacuum or reduced pressure acts on the ball  80  to pull the ball off its valve seat with the spring  82  being compressed. The vacuum or reduce pressure then sucks hydraulic fluid through the suction conduit  70  from the hydraulic reservoir  14  into the rear section  34   b.    
     Referring also to FIG. 3, the tool  10  it is shown with the ram  20  advanced into contact with an electrical connector C to sandwich the connector between the section  28  and the ram  20 . When this occurs, the connector C is about to be compressed or crimped between the section  28  and ram  20  onto the electrical conductor E located inside the connector C. When the ram  20  meets a predetermined resistance to its forward movement by contact with the connector C, a predetermined hydraulic pressure is generated in the front section of area  58 . The valve formed in the pump bypass conduit  68  is adapted to open at this predetermined hydraulic pressure. Thus, the ball  76  moves away from its valve seat and hydraulic fluid can now flow through the pump bypass conduit  68  from the front section of the area  58  into the rear section  34   b  of the ram chamber  34 . 
     Because the area of the surface  33  at the rear end  32  of the ram  20  is larger than the surface  35  at the rear end of the actuator  74 , and because the pump  18  has not changed its speed, the ram  20  is moved forward at a second slower rate of movement. The actuator  74  continues to move forward with the ram  20 , but it is not the primary motive force. Instead, the ram  20  is primarily moved forward by the hydraulic pressure in the rear section  34   b  of the chamber  34 . Although the ram  20  moves forward at a slower rate of movement, the size of the area on the surface  33  allows the hydraulic pressure in the rear section  34   b  to generate a relatively larger force against the electrical connector C (Force=Pressure×Area; F=P·A) to thereby crimp or compress the electrical connector onto the electrical conductor E. 
     Even though the pump  18  can have a relatively constant speed, the ram  20  can move at two different speeds because of the multi-speed ram advancement system described above. The multi-speed ram advancement system automatically switches from the first relatively fast speed movement of the ram to the second relatively slower movement of the ram When the ram encounters a predetermined resistance to forward movement. The tool  10  preferably comprises a pressure relief valve when pressure in the rear section  34   b  of the chamber  34  reaches a predetermined pressure, such as 7000-10000 psi for example. However, in alternate embodiments, any suitable type of pressure relief system could be provided. After compression or crimping of the connector C is complete, the user can release the trigger switch  40  and actuate the user actuated member  72  to allow hydraulic fluid in the rear end section  34   b  to return to the reservoir  14  with the spring  36  returning the ram  20  to its rear home position. 
     The present invention provides a battery operated hydraulic compression tool which has a much faster crimp speed than conventional battery operated hydraulic compression tools. The present invention can use a cartridge style of hydraulic pump to minimize cost, weight and size of the tool. Even though the cartridge style pump has a relatively low volume-to-revolution hydraulic fluid output, the present invention allows use of this cartridge style pump by use of a rapid ram advancement system, to provide a relatively fast ram movement speed from the retracted home position shown in FIG. 2 to the connector contact position shown in FIG.  3 . 
     It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.