Patent Application
20170080555
The present disclosure relates to the field of hydraulic hammers. In particular, the present disclosure relates to hammer temperature protection system for a hydraulic hammer
Hydraulic hammers can be attached to various machines such as excavators, backhoes, tool carriers, or other like machines for the purpose of milling stone, concrete, and other construction materials. The hydraulic hammer is mounted to a boom of the machine and connected to a hydraulic system. High pressure fluid is then supplied to the hammer to drive a reciprocating piston and a work tool in contact with the piston.
During prolonged hours of operation or during working in extremely hot environments the hydraulic fluid may get heated. Further, inefficiencies in the hydraulic system of the hammer or the machine may also often result in overheating of the hydraulic fluid. Operating the hammer with overheated fluid may damage the hammer components. U.S. Pat. No. 4,474,248 discloses providing a thermostat on a truck platform that can direct the hydraulic fluid towards a cooler when the fluid temperature is excessively high.
A hydraulic hammer including a housing, a piston arranged for reciprocating movement within the housing, a hydraulic circuit within the housing. The hydraulic circuit is configured for connection to a source of pressurized fluid. The hydraulic circuit includes an inlet passage configured to provide a hydraulic fluid to the piston, an outlet passage configured to provide a return flow path for the hydraulic fluid from the piston a bypass passage selectively connecting the inlet passage to the outlet passage and a thermostatic valve assembly configured to connect the inlet passage to the piston when the temperature of the hydraulic fluid is below a threshold temperature and connect the inlet passage to the bypass passage when the temperature of the hydraulic fluid is above the threshold temperature.
A work machine including a source of pressurized fluid, a fluid cooling system and a hydraulic hammer is disclosed. The work machine may include a piston arranged for reciprocating movement within the housing and a hydraulic circuit within the housing and configured for connection to the source of pressurized fluid. The hydraulic circuit may include an inlet passage configured to provide hydraulic fluid to the piston, an outlet passage configured to provide a return flow path for hydraulic fluid from the piston, a bypass passage selectively connecting the inlet passage to the outlet passage and a thermostatic valve assembly configured to connect the inlet passage to the piston when the temperature of the hydraulic fluid is below a threshold temperature and connect the inlet passage to the bypass passage when the temperature of the hydraulic fluid is above the threshold temperature.
A method of operation of a hydraulic hammer is disclosed. The hydraulic hammer includes a housing, a piston arranged for reciprocating movement within the housing, a hydraulic circuit within the housing. The hydraulic circuit may be configured for connection to a source of pressurized fluid. The hydraulic circuit includes an inlet passage configured to provide hydraulic fluid to the piston, an outlet passage configured to provide a return flow path for the hydraulic fluid from the piston, a bypass passage selectively connecting the inlet passage to the outlet passage and a thermostatic valve assembly. The method of operating such hammer includes conveying the hydraulic fluid to the piston from the inlet passage when the temperature of the hydraulic fluid is below a threshold temperature and conveying at least some of the hydraulic fluid to the outlet passage through the bypass passage when the temperature of the hydraulic fluid is above the threshold temperature.
In the disclosed embodiment, one or more hydraulic cylinders 15 may raise, lower, and/or swing boom 12 and arm 16 to correspondingly raise, lower, and/or swing hammer 20. The hydraulic cylinders 15 may be connected to a hydraulic supply system (not shown) within work machine 10. Specifically, work machine 10 may include a pump (not shown) connected to hydraulic cylinders 15 and to hammer 20 through one or more hydraulic supply lines (not shown). The hydraulic supply system may introduce pressurized fluid, for example oil, from the pump and into the hydraulic cylinders 15. Operator controls for movement of hydraulic cylinders 15 and/or hammer 20 may be located within a cabin 11 of work machine 10.
As shown in
As shown in
Referring to
Further, a bypass passage 120 may be defined in the housing 40. The bypass passage 120 fluidly connects the inlet passage 102 with the outlet passage 112. A thermostatic valve assembly 125 may be disposed in the hydraulic circuit 84 to selectively open the bypass passage 120.
Referring to
The valve may be actuated by a thermostatic actuator, for example a bimetallic strip, a bimetallic coil or a bimetallic spring, etc. The thermostatic actuator may be exposed to the hydraulic fluid in the inlet passage 102. The thermostatic actuator may be configured to actuate the valve to fully or partially open the bypass passage 120 when the temperature of the fluid crosses a predetermined threshold. Opening of the bypass passage 120 may permit fluid in the inlet passage 102 to flow towards the outlet passage 112. When the valve is open, bypass passage 120 may provide for the least resistance path for the hydraulic fluid in the inlet passage 102. In an embodiment, the thermostatic actuator may be configured to gradually open the bypass passage 120 from a partially open to a fully open state in response to the rise in temperature of the hydraulic fluid in the inlet passage 102. The thermostatic actuator may be directly or indirectly exposed to the hydraulic fluid or heat from the hydraulic fluid for actuating the vale.
When the valve opens the bypass passage 120, the hydraulic fluid entering from the inlet 100 may be partially or completely returned to the source of hydraulic fluid without doing any work in the hammer 20. The quantity of the hydraulic fluid being bypassed or returned by the hydraulic circuit 84 may depend on the extent of actuation of the valve. When the temperature of the fluid is below a certain predetermined threshold, the valve may be in a closed state. In the closed state, the valve may restrict any fluid flow in the bypass passage 120 and all the fluid received from the inlet 100 may be directed for operation of the hammer 20 for reciprocating the piston 80 in the housing 40. When the temperature of the fluid crosses a threshold, the thermostatic actuator may actuate the valve to open the bypass passage 120. On opening the bypass passage 120, the fluid entering the inlet 100 may move from the inlet passage 102 to the outlet passage 112 through the bypass passage 120 and then out of the hammer 20 from the outlet 110. In an embodiment, the valve may be configured to direct all the fluid from the inlet passage 102 to the outlet passage 112 through the bypass passage 120. When the bypass passage 120 is fully or partially open, the hammer 20 may be configured to stop operation or operate with reduced capacity.
The work machine 10 may have a fluid cooling system 90 for cooling the hydraulic fluid. The stalling or reduced capacity of the hammer 20 in the event of the opening of the bypass passage 120 may alert the operator to take appropriate action, for example halting the operation for some time or adjusting a fluid cooling system 90. When the valve is opened by the thermostatic actuator, the fluid that is returned by the valve may be sent to the fluid cooling system 90 for cooling the fluid. The fluid may be cooled with the fluid cooling systems 90 known in the art. Subsequently, when the hammer 20 receives fluid with the temperature below a certain threshold, the valve may be closed by the thermostatic actuator in response to the drop in the temperature of the hydraulic fluid and resume the supply of fluid to the hammer 20 for resuming the normal operating condition of the hammer 20.
The present disclosure provides for a hammer protection system for protecting a hammer 20 from overheated fluid. In an instance, a work machine 10 may be configured for attachment of various other tools like excavating buckets, claws, augers, post hole rippers, etc. The temperature protection system on the work machine 10 may not be adequate for protection of the components of the hammer 20. In the hammer temperature protection system in accordance with the present disclosure, the thermostatic valve assembly 125 may be adjusted in accordance with the temperature tolerance levels of various components in the hammer assembly.
Further, the present disclosure provides for an inbuilt hammer temperature protection system for a hammer 20. The hammer temperature protection system in accordance with the present disclosure protects the hammer 20 from overheated fluid irrespective of whether the work machine 10 has a temperature protection system in place. Therefore, the hammer 20 incorporated with the temperature protection system in accordance with the present disclosure may be used with different work machines.
The reduced capacity of the hammer 20 in the event of the opening of the bypass passage 120 may alert the operator of an overheating situation and prompt the operator to take appropriate action, for example halting the operation for some time or adjusting the fluid cooling system 90 of the work machine 10.
The hammer protection system in accordance with the present disclosure provides for a simple and cost effective solution for protection of hammer 20 from overheated fluids.
Further, the hammer temperature protection system in accordance with the present disclosure may reduce downtime and cost of service or maintenance by protecting hammer 20 from damages occurring due to excessive temperature of the fluid.
Referring to
In an embodiment, method 300 may include conveying all the hydraulic fluid from the inlet passage to the outlet passage when the temperature of the hydraulic fluid is above the threshold temperature. In an embodiment, the method 300 may include the thermostatic valve assembly 125 being actuated by a bimetallic member. In another embodiment, the method 300 may include directing the fluid from the bypass passage to a cooling system when the temperature of the fluid crosses the threshold. In another embodiment, the method 300 may include closing the bypass passage when the temperature of the fluid returns below a threshold temperature. Further, in an embodiment, the method 300 may include stopping the hammer operation when the temperature of the fluid crosses the threshold. In another embodiment, the method 300 may include connecting the hydraulic hammer to a source of pressurized fluid on a work machine
When the temperature of the fluid is above the threshold, the fluid returned by the thermostatic valve assembly 125 may be sent to a fluid cooling system 90 for cooling the fluid. Once the fluid reaches to suitable temperature, the fluid may again be routed to the hammer 20 for operation. When the thermostatic valve assembly 125 receives the fluid with the temperature of the fluid below the threshold temperature, the thermostatic actuator may close the valve and return the hammer 20 to normal operating condition at full capacity. This way the hammer protection system in accordance with the present disclosure may automatically return the hammer 20 to full capacity when the temperature of the fluid falls below the threshold temperature.
