Input apparatus

Abstract: An input apparatus capable of concurrently accommodating itself to any external signal from a different hydraulic control system or the like. The apparatus includes electrical load sensors (48) each arranged on a push rod (14) or block (18) for detecting the amount of operation of a control lever (12) to generate an electrical signal corresponding to the amount of operation of the control lever. Also, an input apparatus which is capable of concurrently responding to both a signal generated by itself and an external signal fed thereto is provided. The apparatus includes a pilot section (148; 160; 162,164) for exerting force which permits a shuttle (128) to be moved against coiled compression springs (114, 118). The pilot section is fed with a signal from an external hydraulic control system.

Description: This invention relates to an input apparatus adapted to be mounted on a machine equipped with a plurality of actuator driving circuits such as is found with civil engineering equipment, construction equipment or the like. Also, the present invention relates to an input apparatus adapted to control its output by means of an external signal input thereto as well as by operation through its own control section. In general, manual operation of a hydraulic driving circuit equipped with a plurality of actuators and arranged in a construction machine or the like has been conventionally carried out by means of a hydraulic joy stick which is a kind of input apparatus. Most conventional input apparatus is only able to generate a hydraulic signal. Thus, it is necessary to provide an electrical input apparatus separate from the hydraulic input apparatus when it is desired to control an electrical actuator actuated by an electrical signal, in addition to controlling a hydraulic actuator by a hydraulic signal. Also, even when it is possible to provide such an electrical input apparatus separate from the hydraulic input apparatus as described above, an operator must be skilled in order concurrently to operate both input apparatuses in association with each other. In EP-A-0117806, there is disclosed a hydraulic input apparatus in the form of a pilot valve comprising: a control section; a body formed with a pump passage and an output port; push rods arranged in said body and operatively connected to said control section; elastic means arranged in said body and operatively connected to each of said push rods; two shuttles having a pressure receiving surface and being formed with a passage; whereby a selected pressing operation of said control section causes a corresponding shuttle to be moved through its push rod in one direction against said elastic means to permit said passage of said corresponding shuttle to communicate with said pump passage of said body, resulting in feeding hydraulic oil from a hydraulic pump through said corresponding shuttle to said output port of said body and balancing a back pressure acting on said pressure receiving surface of said corresponding shuttle through said output port and elastic force of said elastic means with each other to determine a position of said corresponding shuttle and therefore a hydraulic pressure output through said output port depending on the amount of operation of said control device. However, in EP-A-0117806 a pilot section is fed from a different hydraulic control system. The pilot section 10 communicates with both the hydraulic chambers beneath the respective shuttles on either side thereof through two opposed lateral passages. Accordingly, the additional pressure is applied to each of the push rods rather than to just a selected one of the push rods. There is a chamber which communicates with the pilot section 10, but this is to prevent a pressure being accumulated in the hydraulic chambers beneath the respective shuttles. In EP-A-0383560 a control device for a construction machine is described which is capable of permitting an operator readily to accomplish both hydraulic control and electrical control in association with each other. It is an object of the present invention to provide an input apparatus which is capable of concurrently accommodating itself to any external signal from a different or external hydraulic control system or the like. It is still another object of the present invention to provide an input apparatus which is capable of concurrently responding to both a signal generated by itself and an external signal fed thereto. In accordance with the present invention, we provide an input apparatus comprising a control device, a body formed with a pump passage and an output port, push rods arranged in said body and operatively connected to said control device, elastic means arranged in said body and operatively connected to each of said push rods, two shuttles linearly moveable in said body and each operatively connected to a respective one of said push rods, each of said shuttles having a pressure receiving surface and being formed with a passage, whereby a selected pressing operation of said control device causes a corresponding shuttle to be moved through its push rod in a first direction against said elastic means to permit said passage of said corresponding shuttle to communicate with said pump passage of said body, resulting in feeding hydraulic oil from a hydraulic pump through said corresponding shuttle to said output port of said body and balancing a back pressure acting on said pressure receiving surface of said corresponding shuttle through said output port and an elastic force of said elastic means with each other to determine a position of said corresponding shuttle and therefore a hydraulic pressure output through said output port depending on the amount of operation of said control device, characterised in that: a pilot section is arranged for exerting a force onto said corresponding shuttle which permits said shuttle to be moved in a second direction against said elastic means, and said pilot section is fed with a signal from a different hydraulic control system. The present invention is now described by way of example with reference to the accompanying drawings, in which:- FIGURE 1 is a vertical sectional view showing a conventional prior art input apparatus; FIGURE 2 is a vertical sectional view showing a conventional prior art input apparatus of another type; FIGURE 3 is a circuit diagram of the conventional input apparatus shown in Figure 2; FIGURE 4 is a vertical sectional view showing a first embodiment of input apparatus according to the present invention; FIGURE 5 is a vertical sectional view showing a modification of the input apparatus of Figure 4; and FIGURE 6 is a vertical sectional view showing another modification of the input apparatus of Figure 4. Referring to Figure 1, the input apparatus shown therein is a hydraulic type including a body 10 and a control lever 12 mounted on a central position of an upper portion of the body 10 so as to act as a control section. The control lever 12 is arranged so as to be inclinedly moved in two directions perpendicular to each other or X and Y directions. Also mounted on the body 10 are four push rods 14, which comprise one set of two push rods 14 arranged in an X direction and the other set of two push rods 14 arranged in a Y direction perpendicular to the X direction. Each set of push rods 14 corresponds to each one actuator (not shown). Thus, it will be noted that the input apparatus shown in Figure 1 is so constructed that the single control lever 12 operates two actuators. The body 10 is formed therein with a chamber 16 corresponding to each of the push rods 14 in a manner to be positioned below the push rod. In each of the chambers 16 is arranged a block 18, which is operatively connected at an upper end thereof to the push rod 14 and provided on a lower end thereof with a plate 20. To the plate 20 is operatively connected a vertically movable spool 22 which is formed in a lower portion thereof with a passage 24. The passage 24 is formed at an upper portion thereof with a port 26 which communicates with an exterior of the input apparatus as described below. The spool 22 has a support member 28 securely fitted on an intermediate portion thereof. Another support member 30 is fixedly arranged on the above-described lower end of the block 18 in a manner to surround the plate 20. In each chamber 16 a coiled spring 32 is arranged between the support member 30 and a bottom of the chamber 16. Another coiled spring 34 is arranged within the spring 32 and between the support member 28 and the support member 30. A further coiled spring 36 is arranged inside the coiled spring 34. The body 10 is formed with a pump port 38, as well as a hydraulic oil feed passage 40 communicating with the pump port 38. Also, the body 10 is provided at a portion thereof below each of the spools 22 with an output port 42 communicating with an actuator (not shown). In Figure 1, only two push rods 14 and the construction associated therewith are shown; however, the other two push rods (not shown) are constructed in the same manner. The above-described conventional input apparatus operates as follows:- When the control lever 12 is operated downwardly to force the push rod 14 shown on the right side in Figure 1, the coiled springs 21 and 34 are compressed between the plate 20 and support member 30 and downwardly push the spool 22. This permits the port 26 of the spool 22 to communicate with the hydraulic oil feed passage 40, resulting in pressure or hydraulic oil being discharged through the port 26, passage 24 and output port 42 to the actuator (not shown). Also, such flowing of the hydraulic oil concurrently leads to generation of force which causes the spool 22 to be forced upwardly. The force thus generated is balanced with elastic force of the coiled spring 34, so that a pressure under which the hydraulic oil is discharged through the output port 42 is determined in association with the push rod 14. The above-described operation is likewise carried out also when the control lever 12 is further operated in the same direction to compress the coiled spring 36. In this instance, elastic force of the coiled springs 34 and 36 and the above-described hydraulically generated force for upward biasing the spool 22 are balanced with each other. Another conventional input apparatus in the form of a pilot valve, used for various industrial equipment is shown in Figure 2 and includes a body 100, which is formed therein with four chambers 102 as in the apparatus shown in Figure 1, although Figure 2 shows only two such chambers. The chambers 102 each are continuously formed at a lower portion thereof with a passage 104 and an output port 106 in a manner to communicate with each other. In the chamber 102, a vertically movable shaft member 108 is provided. The shaft member 108 has a support member 110 fitted on its upper end and a support member 112 on its lower end, and between the support members 110 and 112 a coiled spring 114 is provided. A further support member 116 is provided in chamber 102 below the support member 112, and between the support member 116 and the bottom of the chamber 102 is a further coiled compression spring 118, the two springs 114, 118 serving as biassing means. The remaining three chambers are constructed in the same manner as in the construction of Figure 1. The input apparatus also includes a push rod 120 vertically movably arranged above each of the shaft members 108. Above the four push rods 120 is commonly arranged a press member 122 acting as a part of a control section, and to the press member 122 is operatively connected a lever 124 acting as another part of the control section. The push rods 120, the press member 122 and a lower portion of the lever 124 are surrounded with a bellows-like cover 126. In each of the passages 104, a vertically slidable shuttle 128 is provided, which has on a side wall thereof, upper and lower laterally extending vertically spaced passages 130 and 132. The shuttle 128 is also provided therein with a vertically extending passage 134 communicating with the lateral passages 130 and 132. The vertical passage 134 communicates with the output port 106. In addition, the body 100 is formed therein with a pump passage 136, to which a hydraulic pump 138 is connected. The body 100 is also formed therein with a tank passage 140, to which a tank 142 is connected. Figure 3 shows a circuit of the input apparatus or pilot valve thus constructed. In the pilot valve constructed as described above, when the lever 124 is operated to force the push rod 120 shown on the right side of Figure 2 downwards, the coiled compression spring 118 is compressed and moves the shuttle 128 downward. Such lowering of the shuttle 128 permits the passage 130 to communicate with the pump passage 136, so that pressure or hydraulic oil from the hydraulic pump 138 is fed through the pump passage 136, passage 130 and passage 134 to the output port 106. At this time, a back pressure from the output port 106 acts on a pressure receiving lower end surface 144 of the shuttle 128, so that the back pressure and elastic force of the coiled compression springs 114 and 118 are balanced with each other to control a position of the shuttle 128 and therefore hydraulic oil is discharged from the output port 106. When the back pressure acting on the pressure receiving surface 144 is increased, the shuttle 128 is pushed down to a position at which the passage 132 of the shuttle 128 communicates with the tank passage 140, resulting in hydraulic oil being returned through the passages 132 and 140 to the tank 142. As can be seen from the foregoing, the conventional input apparatus or pilot valve constructed as described above is adapted to output hydraulic pressure of a predetermined level depending on the amount of operation of the lever 124 to the output port 106. Unfortunately, the input apparatus completely fails to control its output by means of an external signal such as a hydraulic signal output from a different or external hydraulic control system or the like, and thus fails to operate in association with the external hydraulic control system. The present invention has been made in view of the foregoing disadvantages of the prior art. The input apparatus shown in Figure 4 is adapted to eliminate disadvantages encountered with the conventional input apparatus described with reference to Figures 2 and 3 and like parts are identified with the same reference numerals. In the input apparatus or pilot valve shown in Figure 4, the shuttle 128 is formed on an outer surface of a lower portion thereof into a reduced diameter to provide a step which serves as another pressure receiving surface 146. Correspondingly, the body 100 is formed therein with an external hydraulic signal passage 148 acting as a pilot section, to which an external hydraulic signal is selectively input from a different or external hydraulic control system or the like. The remaining part of the illustrated embodiment may be constructed in substantially the same manner as the conventional input apparatus or pilot valve shown in Figure 2. Operation of the control lever 124 causes the shuttle 128 to be moved through the corresponding push rod 120 and shaft member 108 in one direction. This results in the passage 132 of the shuttle 128 and the pump passage 136 of the body 100 communicating with each other, so that hydraulic oil from the hydraulic pump 138 is fed through the shuttle 128 to the output port 106 of the body 100. The back pressure acting on the pressure receiving surface 144 is balanced against the elastic force of elastic means 114 and 118; hence, the position of the shuttle 128 and therefore the hydraulic pressure output through the output port 106 depends on the amount of operation of the control lever 124. If an external hydraulic signal is fed from a different or external hydraulic control system through the external hydraulic signal passage 148 to the input apparatus during the hydraulic control operation, hydraulic pressure acts on the surface 146 of the shuttle 128 to exert extra upward force on the shuttle 128. This extra force and the elastic force of the coiled compression coils 114 and 118 are balanced with each other to reduce hydraulic pressure output through the output port 106. Thus, the external hydraulic signal can control hydraulic pressure output through the output port 106. Therefore, the input apparatus is actuated by means of the external hydraulic signal from the different hydraulic control system as well as through operation by its own control section, resulting in providing a multi-functional pilot valve. In the modification shown in Figure 5, the arrangement of passages in the body 100 and in the shuttle 128 are different. The shuttle 128 has two vertically spaced passages 150,152 formed on an outer periphery thereof, and the body 100 is formed therein with a pump passage 154 and a passage 156. A relationship is established between the passages 150 and 152 of the shuttle 128 and the passages 154 and 156 of the body 100 so that during normal operation, lowering of the shuttle 128 causes the pump passage 154 and passage 156 to communicate with each other through the upper passage 150 to permit hydraulic oil to be fed from a hydraulic pump 138. On the contrary, when an external hydraulic signal acts on a pressure receiving surface 158 of the shuttle 128 from a different or external hydraulic control system (not shown) or the like through an external hydraulic signal passage 160, the shuttle 128 is moved upwards correspondingly to decrease feeding of hydraulic oil through the passage 150. Thus, it will be noted that the modification likewise permits hydraulic oil fed through an output port 106 to be controlled by means of an external hydraulic signal fed through the external hydraulic signal passage 160. The modification of Figure 6 is constructed in such a manner that the shuttle 128 is integrally provided at a lower portion thereof with a core 162, and a solenoid 164 mounted on the body 100 surrounds the core 162. In this construction of the pilot valve, selective excitation of the solenoid 164 by means of a signal fed thereto from a different or external hydraulic control system permits the core 162 and therefore the shuttle 128 to be forced upwards. In other respects, the apparatus operates in substantially the same way as the input apparatus shown in each of Figures 4 and 5. As can be seen from the foregoing, the input apparatus of the embodiment shown in Figures 4 to 6 is actuated by means of an external signal fed thereto through the pilot section in addition to by operation of its own control section, thereby to exhibit an additional function. It will of course be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the appendant claims

Claims: An input apparatus comprising a control device (124), a body (100) formed with a pump passage (136) and an output port (106), push rods (120) arranged in said body and operatively connected to said control device, elastic means (114, 118) arranged in said body and operatively connected to each of said push rods, two shuttles (128) linearly moveable in said body and each operatively connected to a respective one of said push rods, each of said shuttles having a pressure receiving surface (144,146) and being formed with a passage (130,132,134), whereby a selected pressing operation of said control device (124) causes a corresponding shuttle (128) to be moved through its push rod (120) in a first direction against said elastic means (114,118) to permit said passage of said corresponding shuttle (128) to communicate with said pump passage (136) of said body (100), resulting in feeding hydraulic oil from a hydraulic pump through said corresponding shuttle (128) to said output port (106) of said body (100) and balancing a back pressure acting on said pressure receiving surface of said corresponding shuttle (128) through said output port (106) and an elastic force of said elastic means (114,118) with each other to determine a position of said corresponding shuttle (128) and therefore a hydraulic pressure output through said output port (106) depending on the amount of operation of said control device (124), characterised in that: a pilot section (148, 160, 162, 164) is arranged for exerting a force onto said corresponding shuttle (128) which permits said shuttle (128) to be moved in a second direction against said elastic means (114, 118), and said pilot section is fed with a signal from a different hydraulic control system. An input apparatus as defined in claim 1, characterised in that said pilot section comprises an external hydraulic signal passage (148, 160) provided in said body (100), and in that the shuttles (128) are provided with a second pressure receiving surface onto which said pilot section exerts its force. An input apparatus as defined in claim 1, characterised in that said pilot section comprises a combination of a solenoid (164) and a core (162) actuated due to excitation of said solenoid. An input apparatus as defined in claim 3, characterised in that said core (162) is arranged on said shuttle (128) and said solenoid (164) is arranged on the side of said body (100). An input apparatus as defined in any one of claims 1-4, characterised in that said input apparatus is in the form of a pilot valve.

Inventors: KOIWAI HIDESHI, NARITA SUSUMU, YONEKUBO YOSHITAKE, KOIWAI, HIDESHI, YONEKUBO, YOSHITAKE
Applicants: KAYABA INDUSTRY CO LTD, KAYABA INDUSTRY CO., LTD.
Application year: 1992
Main classification: F15B13
IPC codes: F15B13, E02F9, G05G9