Hydraulic torque wrench and control system for a hydraulic torque wrench

Abstract

A hydraulic torque wrench comprises a ratchet link, a power head, and a signal carrying connector for connection to a controller. The ratchet link includes a housing and a drive plate mounted for rotation about an axis within the housing, the drive plate mounting one part of a first part of a ratchet drive. A socket is mounted for rotation within the housing, the socket providing a second part of the ratchet drive. During rotation of the drive plate in one direction the first and second part of the ratchet drive engage each other to cause rotation of the socket with the drive plate and during rotation of the drive plate in a second direction one of the first and second parts of the ratchet drive rides over the other such that the socket remains stationary while the drive plate rotates. The power head includes a piston and cylinder and hydraulic connections adapted for connection to a source of pressurised hydraulic fluid. The torque wrench mounts a proximity sensor connected to the signal carrying connector and configured to detect maximum extension of the piston. When maximum extension of the piston is detected the proximity sensor emits an electrical signal.

Claims

1. A combination of a hydraulic torque wrench and a hydraulic power pack, the combination comprising: the hydraulic torque wrench having a ratchet link including a socket for engaging with a fastener and a ratchet lever that is configured to rotate the socket to tighten the fastener, a power head including a piston that is coupled to the ratchet lever such that movement of the piston causes the ratchet lever to rotate the socket, and a proximity sensor configured to detect a presence of the ratchet lever, the hydraulic power pack having a hydraulic pump and a hydraulic circuit configured cycle the piston by alternately providing a pressurized hydraulic fluid to opposite sides of the piston, and a controller communicatively coupled to the proximity sensor and being configured to control the hydraulic power pack, wherein the controller is further configured to cause the hydraulic power pack to stop cycling the piston when the proximity sensor does not detect the presence of the ratchet lever within a predetermined time.

2. The combination according to claim 1, wherein the controller includes a data logger configured to record a previous torque applied when the proximity sensor does not detect the presence of the ratchet lever within the predetermined time.

3. The combination according to claim 1, wherein the controller includes a data logger configured to record identifying information of the hydraulic torque wrench.

4. The combination according to claim 1, wherein the controller includes a data logger configured to record identifying information associated with an object on which the hydraulic torque wrench is being used.

5. The combination according to claim 1, wherein the piston is configured to move linearly and the ratchet lever is configured to rotate based on movement of the piston.

6. The combination according to claim 5, further comprising an attachment means configured to take up relative movement between the piston and the ratchet lever as the piston moves linearly and the ratchet lever rotates.

7. The combination according to claim 6, wherein the attachment means includes a pin and a slot.

8. The combination according to claim 1, wherein the ratchet link includes a housing for the ratchet lever and wherein the proximity sensor is coupled to the housing.

9. The combination according to claim 1, wherein the hydraulic torque wrench includes an electronic identifier having identifying information selected from the group consisting of a tool serial number, a tool type, a required tool operating pressure, and a pressure torque ratio, and further wherein the controller is configured to set a hydraulic pressure of the hydraulic power pack based on the identifying information from the electronic identifier.

10. The combination according to claim 1, wherein the hydraulic power pack includes a hydraulic pressure sensor configured to sense a fluid pressure in the hydraulic circuit, and wherein the controller is configured to increase a duty cycle of the hydraulic pump based on the fluid pressure.

11. The combination according to claim 1, wherein the hydraulic power pack includes a hydraulic fluid cooler.

12. The combination according to claim 11, wherein the hydraulic power pack includes a temperature sensor configured to sense a temperature of the pressurized hydraulic fluid, and a wherein the controller is configured to operate the hydraulic fluid cooler based on the temperature.

13. The combination according to claim 1, further comprising a control device configured to cause the hydraulic power pack to cycle the piston when the proximity sensor detects the presence of the ratchet lever.

14. The combination according to claim 13, wherein the control device is a hand-operated control device.

15. The combination according to claim 13, wherein the control device includes an on/off switch having an on position in which the hydraulic power pack cycles the piston and an off position in which the hydraulic power pack does not cycle the piston.

16. The combination according to claim 13, further comprising an indicator configured to indicate that a required torque has been reached when the proximity sensor does not detect the presence of the ratchet lever within the predetermined time.

17. A method of operating the combination according to claim 13, comprising connecting the hydraulic torque wrench to an apparatus having the fastener and operating the control device to initiate cycling of the piston, continuing cycling of the piston when the proximity sensor detects the presence of the ratchet lever, and then automatically stopping cycling of the piston via the controller when the proximity sensor does not detect the presence of the ratchet lever within the predetermined time.

18. The method according to claim 17, further comprising indicating that a required torque has been reached when the proximity sensor does not detect the presence of the ratchet lever within the predetermined time.

19. A combination of a hydraulic torque wrench and a hydraulic power pack, the combination comprising: the hydraulic torque wrench having a ratchet link including a socket for engaging with a fastener and a ratchet lever that is configured to rotate the socket to tighten the fastener, a power head including a piston that is coupled to the ratchet lever such that movement of the piston causes the ratchet lever to rotate the socket, and a proximity sensor configured to detect a presence of the ratchet lever, the hydraulic power pack having a hydraulic pump and a hydraulic circuit configured cycle the piston by alternately providing a pressurized hydraulic fluid to opposite sides of the piston, a controller configured to control the hydraulic power pack and is communicatively coupled to the proximity sensor, wherein the controller is configured to cause the hydraulic power pack to stop cycling the piston when the proximity sensor does not detect the presence of the ratchet lever within a predetermined time, and a control device configured to cause the hydraulic power pack to cycle the piston when the proximity sensor detects the presence of the ratchet lever, wherein operation of the control device causes the hydraulic power pack to continue cycling of the piston as long as the proximity sensor detects the presence of the ratchet lever within a predetermined time.

20. The combination according to claim 19, further comprising an indicator device configured to indicate that a required torque has been reached when the proximity sensor does not detect the presence of the ratchet lever within the predetermined time.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the Drawings, which illustrate preferred embodiments of the invention, and are by way of example:

(2) FIG. 1 is a cross-sectional elevation through a hydraulic torque wrench;

(3) FIG. 2 is a schematic representation of the hydraulic torque wrench illustrated in FIG. 1 from the reverse side;

(4) FIG. 3 is a block diagram of a system including the hydraulic torque wrench of FIGS. 1 and 2 with hydraulic power and control components;

(5) FIG. 4 shows the system of FIG. 3 in detail; and

(6) FIG. 5 is a schematic representation of a hand held control device; and

(7) FIG. 6 is a schematic representation of a hydraulic power pack.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(8) Referring now to FIG. 1, the hydraulic torque wrench 1 comprises two parts, a ratchet link 2 and a power head 3.

(9) The ratchet link 2 includes a housing 5 and a drive plate 4 mounted in the housing 5. The drive plate 4 mounts a ratchet drive pawl 6, the drive pawl 6 having a series of teeth 6a, which engage with external teeth 7a of a socket 7 when the drive plate 4 rotates in a clockwise direction. When the drive plate 4 is rotated counter clockwise the respective angles of the surfaces of teeth 6a, 7a cause the teeth 6a of pawl 6 to ride over the teeth 7a of socket 7.

(10) The power head 3 includes a housing 10 in which a cylinder 11 is formed. A piston 12 is mounted in the cylinder 11. The piston 12 mounts a piston head 13 which has a curved surface 14. The curved surface 14 engages with a corresponding curved surface 4a of the ratchet lever 4. The curved surfaces 14, 4a provide for relative movement between the piston head 13 and drive plate 4 as the piston moves linearly and the drive plate 4 rotates.

(11) FIG. 2 shows the revers side of the ratchet link 2 and power head 3. It can be seen from this drawing that the piston head 13 includes plate 13a which extends behind the ratchet lever 4. The plate 13a includes a slot shaped opening 13b. A pin 13c passes through the slot 13b and is attached to the ratchet lever 4. The slot takes up the differential movement between the piston 12 and the ratchet lever 4 as the piston moves linearly and the ratchet lever rotates.

(12) The cylinder 11 has two hydraulic fluid ports 15, 16, the port 15 provides for the passage of hydraulic fluid into the space between the top surface 12a of piston 12 and the cylinder 11. The port 16 provides for the passage of hydraulic fluid into the space defined by the bottom surface 12b of the piston 12 and the walls of cylinder 11.

(13) A proximity sensor 20 is mounted in the wall of housing 5 such that when the piston 12 is in its fully extended configuration the surface 4b of the drive plate 4 is directly adjacent the proximity sensor 20.

(14) The function of the proximity sensor 20 is to detect the presence of the drive plate 4. As the drive plate 4 approaches the position shown in FIG. 1 the electronic signal emitted by the proximity sensor 20 changes, indicating that the maximum extension of the piston 12 has been reached. The electronic signal from the proximity sensor is used to reverse the flow of hydraulic fluid in the bores 15, 16. Hydraulic fluid is caused to flow into the port 15, filling the space defined by the top surface 12a of the piston 12 and the walls of cylinder 11. At the same time, hydraulic fluid is forced out of the space defined by the bottom surface 12b of piston 12 and the walls of cylinder 11 through the port 16.

(15) In the illustrated example, the flow of hydraulic fluid into port 15 is controlled by a timer. The volume of hydraulic fluid required to move the piston 12 between its fully extended and fully retracted configurations is known, and hence with knowledge of the flow rate of the hydraulic pump, the time required to return the piston 12 to its retracted position may be calculated.

(16) Alternatively, another proximity sensor may be provided to detect the position of the drive plate 4 relative to the housing 5 or the piston head 13 relative to the housing 10. The change in status of such a proximity sensor would change the direction of flow of hydraulic fluid.

(17) The drive plate 4 is therefore cycled back and forth without the need for the operator to do anything other than depress an actuator which activates the hydraulic pump. The control of direction of flow is controlled electronically according to the output of the proximity sensor 20 and the timer described above. A relatively low hydraulic fluid pressure can be used to cycle the drive plate back and forth until the point where the socket 7 needs to tighten the fastener it is connected to.

(18) The fastener to which the socket 7 is attached is tightened to the required torque when the drive plate 4 does not move with the hydraulic fluid pressure set to match the desired torque. This absence of movement of the drive plate is detected by the signal from the proximity switch. When the fastener is tight, the drive plate 4 will stop moving and hence will not come to the position showing FIG. 1.

(19) Referring now to FIG. 3, the hydraulic torque wrench 1 is connected both hydraulically and electrically to a hydraulic power pack 30 by means of hydraulic hoses 31, 32 and electrical cable 33. A control device 40 is connected electrically to the hydraulic power pack 30 by means of electrical cable 41.

(20) FIG. 4 illustrates the components illustrated in FIG. 3 in detail. The hydraulic power pack 30 comprises a set of components 36 for generating pressurised hydraulic fluid, including a pump unit 36a (which includes an electric motor), a cooler 36b, a proportional pressure limiting valve 36c and a pressure relief valve 36d. The set components 36 provide pressurised hydraulic fluid which is directed to the hydraulic torque wrench 1 by a hydraulic circuit 34 which includes a solenoid operated valve 35a. In one configuration of the hydraulic circuit 34 pressurised hydraulic fluid is directed to the hydraulic torque wrench 1 via hydraulic hose 31, the hydraulic fluid returning through hydraulic hose 32, through solenoid operated valve 35b, which is open, and via port 35e to the cooler 36b. In the other configuration of the hydraulic circuit 34 the solenoid valve 35b is closed and solenoid operated valve 35a is closed. Pressurised hydraulic fluid is directed to the hydraulic torque wrench 1 via hydraulic hose 32 causing the piston 12 to retract, the hydraulic fluid returning through hydraulic hose 31, through solenoid operated valve 35a, through the non-return valve 35d and via port 35e to the cooler 36b. The hydraulic circuit 34 is provided with a pressure gauge 35c.

(21) The cooler 36b may include a temperature sensor and a fan, the temperature sensor being configured to detect when the hydraulic fluid temperature exceeds a threshold temperatures, for example 20 C and cause the fan to operate to keep the hydraulic fluid temperature below a second threshold temperature, for example 30 C.

(22) An electronic controller 38 is connected to various components of the set of components 36 and the hydraulic circuit 34, as described below. The controller 38 includes a processor 38 and a programmable logic controller 38b. The function of the controller 38 is to set the components to which it is connected so that hydraulic fluid is supplied at the correct pressure and flow rate to the particular tool 1 being used.

(23) The controller 38 is connected electrically to the control device 40 and the hydraulic torque wrench 1. The electrical connection to the hydraulic torque wrench includes one connection to the proximity switch 20 and a second to a microchip 21. The micro chip 21 carries information that identifies the connected hydraulic torque wrench and the parameters of operation thereof. The PLC 38b then sets the proportional pressure limiting valve 36c to match the requirements of the connected hydraulic torque wrench 1. The electrical connections to the controller 40 and the hydraulic torque wrench 1, namely the electrical cables 33 and 41 are provided within a single cable 51 which includes both electrical cables 33 and 41.

(24) The control device 40 includes trigger 44 for operating the hydraulic torque wrench, emergency stop 45 and indicator light 46.

(25) The hydraulic hoses 31, 32 and electrical cables 33, 41 may be attached to a reel 50, which provides for convenient storage of the hoses and cables.

(26) The hydraulic cabinet is also provides with a human machine interface 37, which includes touch screen display 37a, a data logger 37f, an emergency stop 37b, a hydraulic fluid high temperature indicator 37c (which illuminates when the hydraulic fluid temperature exceeds the threshold temperature), a pump trip switch 37d and a socket 37e, which is a USB data socket in the illustrated example, for connection to other computer devices for example and which allows data recorded on the data logger to be exported from the data logger.

(27) FIG. 5 illustrates the embodiment of the control device 40 as a pistol grip hand held device comprising a housing 43 providing a hand grip and mounting a trigger 44, which is moved towards the housing 43 to cause the hydraulic power pack 30 to send pressurised hydraulic fluid to the hydraulic torque wrench 1. The electrical cable 41 enters the housing 43 through the base thereof. The housing also mounts an emergency stop button 45 and an indicator light 46.

(28) In operation, when the hydraulic torque wrench 1 is connected to the controller 38 by cable 33, the identity of the hydraulic torque wrench 1 is read and the required settings for the hydraulic pump 36a are downloaded from a database of settings. With the apparatus configured for the connected hydraulic torque wrench, depressing the trigger 44 initiates cycling of the piston 12 within the cylinder 11 begins. Each time the piston is extended such that the surface 4b of the drive plate 4 becomes proximate the proximity sensor 20 the direction of flow of hydraulic fluid in the hoses 31, 32 is reversed to return the piston 12 to its retracted position in cylinder 11. Cycling of the piston runs down the fastener to which the hydraulic torque wrench is connected to a point where the fastener begins to tighten. Cycling of the piston continues while the trigger 44 is depressed and until the surface 4b of the ratchet drive does not become proximate the proximity sensor, which indicates that the fastener is tight.

(29) The PLC 38b is programmed so that hydraulic fluid is pumped into the space defined by the cylinder 11 and the upper surface of the piston 12a such that the piston retract time is a short period, for example 0.5 seconds.

(30) The PLC 38b is programmed so that a torque achieved time, which may be 5 seconds, is required before torque achieved lamp on the control device 40 is illuminated.

(31) The PLC 38b is programmed with a pump idle time which switches off the motor/pump 38a when the pump has been idling for a period of time, which may be 5 seconds.

(32) The PLC 38b is programmed with a pressure required not reached time. This may be set at 7 seconds. If the required hydraulic fluid pressure as sensed by the hydraulic fluid pressure sensor 35f is not reached for the time period, the duty cycle of the pump 38a is increased to increase the hydraulic fluid pressure.

(33) The PLC 38b is programmed with a duty cycle increase rate. An increase in the duty cycle is required where the required pressure is not reached. The duty cycle increase rate is set at 3 seconds. This means that if a duty cycle increase rate is required because the required pressure has not been reached, the duty cycle is increased and the pump is operated at that increased duty cycle for a period of 3 seconds before the duty cycle is increased again, if the required pressure is still not reached.

(34) The apparatus of the invention allows fasteners to be set to a torque automatically, with the operator needing only to operate an on/off switch and without the requirement to watch for rotation fo the fastener whilst also watching a pressure dial. Furthermore, the apparatus may use less energy because it is not necessary to operate at full hydraulic pressure until the fastener starts to tighten.