Flush toilet

Abstract

To provide a siphon jet flush toilet capable of ensuring waste discharge performance by creating sufficient siphoning force even when a water tank is placed in a low silhouette.SOLUTION: A siphon jet flush toilet includes: a rim spout water port for spouting washing water to a bowl; a drain trap pipe; and a jet spout water port for spouting the washing water toward the entrance of the drain trap pipe; and a drain valve 38. The flush toilet further includes: a water tank for storing the washing water supplied to the jet spout water port; a jet waterway that guides the washing water via the head of the water tank to a jet spout water port from the water tank; and a controller that controls rim spout water and jet spout water. The valve body of the drain valve is placed at a position lower than the top of the bowl and higher than the seal water level. The controller is configured to control to spout washing water continuously from the rim spout water port in the order of "pre-rim water spout", "middle rim water spout", and "post rim water spout" in this order, and to perform "jet spout water" from the jet spout water port while performing "middle rim water spout".SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a flush toilet, and more particularly to a siphon jet type flush toilet. [Background technology]

[0002] Conventionally, siphon jet flush toilets have been known in which the rim spout is supplied with water directly from the water mains, and flush water is directed to the jet spout from a low-height water storage tank by head pressure, as described in Patent Document 1. Also known is a siphon jet flush toilet in which front rim spouting, middle rim spouting, and rear rim spouting are performed continuously, and jet water is spouted during middle rim spouting (sequential control), as described in Patent Document 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5180295 [Patent Document 2] JP 2023-32964 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the flush toilet of Patent Document 1 mentioned above, the water storage tank is arranged in a low silhouette, and furthermore, the jet water is directed to the jet water conduit by the head pressure of the flush water in the tank, so the flow rate of the flush water discharged from the jet water outlet is slower than in a flush water outlet that uses a pump to direct flush water to the jet water conduit, and therefore the force of pulling into the drain trap pipe due to siphon action is smaller.In the flush toilet of Patent Document 2 mentioned above, the water storage tank that directs flush water to the jet water outlet is located above the bowl section, so the problem of the pulling force due to siphon action occurring in the flush toilet of Patent Document 1 being smaller does not exist.

[0005] Therefore, the present invention has been made to solve the problems (issues) associated with the conventional technology, and has as its object to provide a siphon jet type flush toilet that can generate a sufficient pulling force through the siphon action to ensure waste discharge performance, even if the water storage tank is positioned with a low silhouette and the jet water is guided to the jet water conduit by the head pressure of the flush water in the water storage tank. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a siphon jet type flush toilet, comprising: a bowl portion having a waste receiving surface and a rim portion formed along the upper edge of the waste receiving surface; a rim spout formed in the rim portion for spouting flush water into the bowl portion; a drain trap pipe connected below the bowl portion, the drain trap pipe having an ascending pipe extending upward from below the bowl portion, a descending pipe extending downward from the ascending pipe, and a top located between the ascending pipe and the descending pipe and defining a seal water level; a jet spout disposed below the bowl portion so as to spout flush water toward an inlet of the drain trap pipe; and a drain valve, The device has a water storage tank for storing flushing water to be supplied to the water spout, a jet water conduit that connects the water storage tank to the jet spout and guides the flushing water from the water storage tank to the jet spout using the head of the water storage tank, and a control device that controls the rim spout and the jet spout from the jet spout, and the drain valve has a valve body that is positioned lower than the top surface of the bowl portion and higher than the seal water level, and the control device controls the flushing water to be successively spouted from the rim spout in order as "front rim spout," "middle rim spout," and "rear rim spout" and to perform "jet spouting" from the jet spout when "middle rim spouting" is occurring. In the present invention thus configured, flush water is successively discharged from the rim spout in the order of "front rim spouting", "middle rim spouting", and "rear rim spouting", and the sequence is controlled so that "jet spouting" is performed from the jet spout when "middle rim spouting" is being performed, so that flush water supplied to the bowl section by the front rim spouting and pooled water remaining in the bowl section by the rear rim spouting during the previous flushing are combined with flush water by the jet spouting, causing a large flow rate of flush water to flow into the drain trap pipe, and the siphoning action can be continued by the flush water by the subsequent jet spouting and the flush water by the middle rim spouting. As a result, according to the present invention, even if flush water is supplied to the jet water conduit by the head pressure of the flush water in the water storage tank with a low silhouette, waste can be reliably discharged by the strong siphoning action, and water saving can also be achieved.

[0007] In the present invention, the water spouting time of the front rim water spouting is preferably shorter than the water spouting time of the rear rim water spouting. According to the present invention configured in this manner, the bowl portion is cleaned by the front rim spouting of a smaller amount of flush water than the rear rim spouting of flush water, and furthermore, a siphon effect can be generated by this flush water.

[0008] In the present invention, the total water spouting time of the front rim water spouting and the middle rim water spouting is preferably shorter than the water spouting time of the rear rim water spouting. According to the present invention configured in this manner, a siphoning action can be generated together with the jet water spout by front rim water spouting and middle rim water spouting, which have a smaller amount of flush water than the rear rim water spouting, thereby allowing siphoning to continue.

[0009] In the present invention, the stop water level of the flush water in the water storage tank is preferably set higher than the upper surface of the bowl surface. According to the present invention configured in this manner, the flush water stop level (WL0) in the water storage tank is set higher than the upper surface of the bowl surface, so that a large head pressure can be achieved.

[0010] In the present invention, the stop water level of the flush water in the water storage tank is preferably set lower than the upper surface of the bowl surface. According to the present invention configured in this manner, the flush water stop water level (WL0) in the water tank is set lower than the upper surface of the bowl surface, making it possible to lower the height of the water tank and achieve a lower silhouette.

[0011] In the present invention, the control device preferably supplies water to the water tank after rear rim water spouting has ended. According to the present invention configured in this manner, water is supplied to the water tank after rear rim water spouting has ended, so that rim water spouting can be continued at a constant flow rate and there is no decrease in flow rate. Effect of the Invention

[0012] With the siphon jet flush toilet of the present invention, even if the water storage tank is positioned with a low silhouette and the jet water is guided to the jet water conduit by the head pressure of the flush water in the tank, a sufficient pulling force is generated by the siphon action, ensuring waste discharge performance. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a plan view showing a flush toilet according to an embodiment of the present invention. [Diagram 2] 2 is a side cross-sectional view taken along line II-II in FIG. 1. [Diagram 3] 1 is a time chart showing "rim spouting," "tank water supply," "jet spouting," and "tank water level" in a flush toilet according to an embodiment of the present invention. [Figure 4A] 1 is a table showing the water spouting times and water spouting volumes of "front rim spouting," "middle rim spouting," "rear rim spouting," and "jet spouting" during a large flush of a flush toilet according to an embodiment of the present invention. [Figure 4B] 1 is a table showing the water spouting times and water spouting volumes of "front rim spouting," "middle rim spouting," "rear rim spouting," and "jet spouting" in a small-flush of a flush toilet according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a diagram for explaining the flushing operation of a flush toilet according to an embodiment of the present invention. [Figure 6A] FIG. 1 is a diagram showing the instantaneous flow rate of flush water spouted from the rim spout during a large flush of a flush toilet according to an embodiment of the present invention, the instantaneous flow rate of flush water spouted from the jet spout, and the instantaneous flow rate of flush water flowing into the inlet of the drain trap pipe. [Figure 6B] A diagram showing the instantaneous flow rate of flush water spouted from the rim spout during a small flush of a flush toilet according to an embodiment of the present invention, the instantaneous flow rate of flush water spouted from the jet spout, and the instantaneous flow rate of flush water flowing into the inlet of the drain trap pipe. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A flush toilet according to an embodiment of the present invention will be described below with reference to the drawings. First, the basic structure of a flush toilet according to this embodiment will be explained with reference to Figures 1 and 2. Figure 1 is a plan view showing a flush toilet according to an embodiment of the present invention, and Figure 2 is a side cross-sectional view taken along line II-II in Figure 1.

[0015] As shown in Figures 1 and 2, the flush toilet 1 of this embodiment is a siphon jet type flush toilet. This flush toilet 1 is equipped with a ceramic toilet body 2, a plastic toilet seat and toilet lid (not shown) placed on the top surface of this toilet body 2, and a water storage tank 4 placed at the upper rear of the toilet body 2 and covered by a plastic cover (not shown).

[0016] The toilet body 2 is formed with a bowl portion 6 for receiving waste, a drain trap pipe 8 provided at the bottom of the bowl portion 6 for discharging waste by siphon action, a rim water outlet 10 for rim water spouting, a rim water conduit 12 for guiding flushing water to the rim water outlet 10, a jet water outlet 14 for jet water spouting, and a jet water conduit 16 for guiding flushing water to the jet water outlet 14.

[0017] The bowl portion 6 comprises a bowl-shaped waste receiving surface 18, a rim portion 20 formed along the upper edge of the bowl portion 6, and a shelf portion 21 formed between the waste receiving surface 18 and the rim portion 20. The bowl portion 6 also comprises a pot portion 22 formed in the area below the waste receiving surface 18 and connected to the drain trap pipe 16. A water sealing surface (reservoir surface) W is formed inside the pot portion 22.

[0018] The drain trap pipeline 8 has an inlet 8a, an ascending pipeline 8b extending upward from the inlet 8a, a descending pipeline 8c extending downward from the ascending pipeline 8b, and a top 8d located between the descending pipeline 8c and the ascending pipeline 8b and determining the sealing water level of the sealing surface W. Here, the lower end of the descending pipe 8c of the drain trap pipe 8 is connected to a drain pipe (not shown) attached to the floor or wall via a drain socket (not shown).

[0019] When looking at the toilet body 2 from the front, the rim spout 10 is formed on the rear left side of the rim portion 20. The rim spout 10 spouts flushing water forward, and this flushing water swirls around the inner circumferential surface of the rim portion 20 and the shelf surface of the shelf portion 21 before flowing down to the waste receiving surface 18 and cleaning the waste receiving surface 18.

[0020] The rim water conduit 12 is formed in a tapered shape with the flow path cross section gradually becoming smaller towards the rim water outlet 10. A water supply hose 23 that is directly connected to a water supply is connected to the upstream side of the rim water conduit 12. Flush water is supplied to the rim water conduit 12 from the water supply, and the flush water is discharged from the rim water outlet 10 by the water supply pressure of the water supply.

[0021] The jet water outlet 14 is formed in the bottom of the bowl portion 6. The jet water outlet 14 is disposed opposite the inlet 8a of the drain trap pipe 8 and is directed toward the inlet 8a of the drain trap pipe 8. The jet water outlet 14 ejects flush water toward the inlet 8a of the drain trap pipe 8, and this flush water flows into the drain trap pipe 8, activating the siphon action.

[0022] The jet water conduit 16 comprises an upstream flow path 16a extending forward from the water storage tank 4, a curved flow path 16b bending from this upstream flow path, and a downstream flow path 16c extending rearward from this curved flow path and connecting to the jet water outlet 14. Flush water is supplied to the jet water conduit 16 from the water storage tank 4, and the flush water is spouted from the jet water outlet 14 by the head pressure of the flush water.

[0023] The water storage tank 4 is a gravity-fed tank that stores flush water to be used for jet spouting and supplies it to the jet spout 14. Flush water is stored in the water storage tank 4 up to the stop water level (WL0), and flush water from the stop water level to the dead water level (DWL) is used for jet spouting. The water storage tank 4 is a small resin tank. The lower part of the water storage tank 4 is positioned below the top surface of the rim part 20 of the toilet body 2, and above the top 8d of the drain trap pipe 8. This makes the flush toilet 1 a low-silhouette type toilet. The water storage tank 4 may be a ceramic tank that is integrated with the toilet body 2.

[0024] Provided within the water storage tank 4 are a water supply device 24 which supplies flush water into the water storage tank 4, a drainage device 26 which supplies or stops the flush water stored in the water storage tank 4 to the jet water conduit 16, and a float switch 28 which detects when the flush water level in the water storage tank 4 has reached the stop water level (WL0). Also provided outside the water storage tank 4 are a controller 29 which controls the water supply device 24 and drainage device 26 to operate or stop based on an operation signal from the user, and an operation unit (not shown) which transmits an operation signal in response to operation by the user.

[0025] The water supply device 24 comprises a constant flow valve (not shown) connected to a water supply, a rim-side solenoid valve 30 which supplies or stops flush water to the rim spout 10, and a tank-side solenoid valve 34 which supplies or stops flush water to a tank water supply port 32 arranged in the water storage tank 4. The rim-side solenoid valve 30 and tank-side solenoid valve 34 are adapted to control their operation by commands from a controller 29 based on operation signals from the user and water level detection signals from a float switch 28.

[0026] The drainage device 26 comprises an overflow pipe 36 that drains overflowing water from the water storage tank 4 into the toilet body, a drain valve 38 fixed to the lower end of the overflow pipe 36, and a toilet flushing unit 40 that opens and closes the drain valve 38 by moving the overflow pipe 36 up and down by an electric driving force. The upper and lower ends of the overflow pipe 36 are open so that overflowing water from the water storage tank 4 can be discharged into the jet waterway 16. A guide member 42 that guides the up and down movement of the drain valve 38 is attached to the periphery of the drain port 4a of the water storage tank 4. The toilet flushing unit 40 is driven by commands from the controller 29 based on an operation signal from the user.

[0027] As described above, the flush toilet 1 is a low-silhouette type toilet, but more specifically, as shown in FIG. 2, the valve body 38a of the jet drain valve 38 is positioned lower than the upper surface of the bowl portion 6 (the upper surface of the rim portion 20) and higher than the seal water level.

[0028] 2, the water stop water level (WL0) of the water storage tank 4 is set higher than the upper surface of the rim portion 20 of the bowl portion 6. As a modified example, the water stop water level may be set lower than the upper surface of the rim portion 20 of the bowl portion 6.

[0029] The controller 29 is electrically connected to the operation unit, the float switch 28, the rim side solenoid valve 30, the tank side solenoid valve 34, and the toilet flushing unit 40, and is capable of sending and receiving various signals. The controller 29 receives a flush start signal for a large flush or small flush from the operation unit, and drives or stops the rim side solenoid valve 30, the tank side solenoid valve 34, and the toilet flushing unit 40 based on a flush sequence stored in advance.

[0030] Next, "rim water spouting," "tank water supply," "jet water spouting," and "tank water level" in a flush toilet 1 according to this embodiment will be explained with reference to Figure 3. Figure 3 is a time chart showing "rim water spouting," "tank water supply," "jet water spouting," and "tank water level" in a flush toilet according to an embodiment of the present invention.

[0031] Here, "rim spouting" refers to spouting flush water from the rim spout 10, "tank water supply" refers to supplying water to the water storage tank 4, "jet spouting" refers to spouting flush water from the jet spout 14, and "tank water level" refers to the level of flush water in the water storage tank 4.

[0032] As shown in Figure 3, during a large flush of the flush toilet 1, first after a standby state at time t0, when the user operates the operating part, at time t1 the rim-side solenoid valve 38 turns ON, commencing rim spouting, which supplies water to the rim water conduit 12 and spouts flush water from the rim spout 10. This rim spouting continues until time t5.

[0033] Next, at time t2, the drain valve 38 is opened and turned ON, and jet spouting begins in which flush water in the water storage tank 4 passes through the jet water conduit 16 and is spouted from the jet water spouting port 14. This jet water spouting ends at time t4. When jet water spouting is being performed from time t2 to time t4, rim water spouting is also being performed at the same time.

[0034] Here, as is clear from Figure 3, for convenience, rim spouting from time t1 when rim spouting begins to time t2 when jet water spouting begins is referred to as "front rim spouting," rim water spouting from time t2 to time t4 when jet water spouting is performed is referred to as "middle rim spouting," and rim water spouting from time t4 when jet water spouting ends to time t5 when rim spouting ends is referred to as "rear rim spouting." Also, as mentioned above, "jet water spouting" is performed from time t2 to time t4.

[0035] Next, as shown in Figure 3, float switch 28 was ON at time t2 when jet water spouting began because the flush water level in the water storage tank 4 was at the stop water level, but then at time t3, the flush water level in the water storage tank 4 drops below the stop water level, so it turns OFF. This OFF state of float switch 28 continues until time t7.

[0036] Also, at time t6, the tank-side solenoid valve 34 is opened and turned ON, starting tank water supply to the storage tank 4, and the tank water supply ends at time t8. As a result of this tank water supply starting at time t6, the flush water level in the storage tank 4 rises, which causes the float switch 28 to return to ON at time t7 as the flush water level in the storage tank 4 rises to the stop water level, entering a full water state.

[0037] The large flush has been explained using Figure 3, but the small flush also applies to the time chart in Figure 3. Note that, as will be described later, the large flush and small flush have different water discharge times and water discharge volumes.

[0038] Next, the spouting times and water spouting volumes of rim spouting and jet spouting in the large flush and small flush will be explained with reference to Figures 4A and 4B. Figure 4A is a table showing the water spouting times and water spouting volumes of "front rim spouting," "middle rim spouting," "rear rim spouting," and "jet spouting" in the large flush of a flush toilet according to an embodiment of the present invention, and Figure 4B is a table showing the water spouting times and water spouting volumes of "front rim spouting," "middle rim spouting," "rear rim spouting," and "jet spouting" in the small flush of a flush toilet according to an embodiment of the present invention.

[0039] As shown in Fig. 4A, in the case of large flush, the front rim water spouting time is 1.9 seconds (s) and the water spouting volume is 0.41 liters (L), the middle rim water spouting time is 2.4 seconds (s) and the water spouting volume is 0.52 liters (L), and the rear rim water spouting time is 6.1 seconds (s) and the water spouting volume is 1.32 liters (L). Also, the jet water spouting time is 2.4 seconds (s) and the water spouting volume is 2.31 liters (L).

[0040] As is clear from Figure 4A, in the case of large flush, the water discharge time of the front rim water discharge (1.9 seconds) is shorter than the water discharge time of the rear rim water discharge (6.1 seconds). Furthermore, the total water discharge time of the front rim water discharge and the middle rim water discharge (1.9 seconds + 2.4 seconds) is shorter than the water discharge time of the rear rim water discharge (6.1 seconds).

[0041] Similarly, as shown in Figure 4B, in the case of a small flush, the front rim water spouting time is 1.4 seconds (s) and the water spouting volume is 0.31 liters (L), the middle rim water spouting time is 1.7 seconds (s) and the water spouting volume is 0.37 liters (L), and the rear rim water spouting time is 7.6 seconds (s) and the water spouting volume is 1.64 liters (L). Also, the jet water spouting time is 1.7 seconds (s) and the water spouting volume is 1.50 liters (L).

[0042] As is clear from Figure 4A, in the case of the small flush, as in the case of the large flush described above, the water discharge time of the front rim water discharge (1.4 seconds) is shorter than the water discharge time of the rear rim water discharge (7.6 seconds). Furthermore, the total water discharge time of the front rim water discharge and the middle rim water discharge (1.4 seconds + 1.7 seconds) is shorter than the water discharge time of the rear rim water discharge (7.6 seconds).

[0043] Next, the flushing operation of a flush toilet according to an embodiment of the present invention will be explained with reference to Figure 5. Figure 5 is a diagram for explaining the flushing operation of a flush toilet according to an embodiment of the present invention.

[0044] 5(a) shows the standby state, in which flush water has accumulated in bowl section 6 up to seal water level W, and flush water has also accumulated in jet conduit 16 up to the same height as the seal water level. At this time, air A is retained in a part of upstream flow path 16a located directly below water storage tank 4.

[0045] Next, as shown in Figure 5 (b), the rim-side solenoid valve 30 opens, rim spouting begins, and the flush water level gradually rises in the bowl section 6. In conjunction with this, the flush water level also gradually rises in the jet water conduit 16, and the trapped air A is discharged from the overflow pipe 36, filling the jet water conduit 16 with water.

[0046] After this, as shown in Figure 5 (c), while rim water spouting continues, drain valve 38 opens and jet water spouting begins. At this time, the pooled water (seal water) remaining in bowl portion 6 and flush water from rim water spouting combine with flush water from jet water spouting, and a large flow rate of flush water flows into drain trap pipe 8, causing a strong siphon effect and discharging waste.

[0047] Next, as shown in Figure 5 (d), while rim water spouting continues, the drain valve 38 closes. Even if the drain valve 38 closes, the rim water spouting and jet water spouting flow into the drain trap pipe 8, so the siphon action can continue.

[0048] After that, as shown in Figure 5 (e), the flush water level in the bowl section 6 drops as the accumulated water is discharged by the siphon action, and air enters from the top of the inlet 8a of the drain trap pipe 8, ending the siphon action. Even after the siphon action ends, the rim spouting continues and ends when flush water accumulates in the bowl section 6 up to the seal water level. At this time, flush water also accumulates in the jet water conduit 16 up to the same height as the seal water level.

[0049] Next, as shown in Fig. 5(f), the tank-side solenoid valve 34 opens and tank water supply begins. When the flush water level in the water storage tank 4 rises and the float switch 28 detects that the flush water level has reached the stop water level, the tank-side solenoid valve 27 closes, and then the system returns to the original standby state as shown in Fig. 5(a).

[0050] Next, the instantaneous flow rate of flush water spouted from the rim spout during the large flush and small flush, the instantaneous flow rate of flush water spouted from the jet spout, and the instantaneous flow rate of flush water flowing into the inlet of the drain trap pipe in a flush toilet according to an embodiment of the present invention will be explained with reference to Figures 6A and 6B. Figure 6A is a diagram showing the instantaneous flow rate of flush water spouted from the rim spout during the large flush of a flush toilet according to an embodiment of the present invention, the instantaneous flow rate of flush water spouted from the jet spout, and the instantaneous flow rate of flush water flowing into the inlet of the drain trap pipe, and Figure 6B is a diagram showing the instantaneous flow rate of flush water spouted from the rim spout, the instantaneous flow rate of flush water spouted from the jet spout, and the instantaneous flow rate of flush water flowing into the inlet of the drain trap pipe in a small flush of a flush toilet according to an embodiment of the present invention.

[0051] In Figures 6A and 6B, the dashed line indicates the instantaneous flow rate of flushing water discharged from the jet water outlet 14, the dotted line indicates the instantaneous flow rate of flushing water discharged from the rim water outlet 10, and the solid line indicates the instantaneous flow rate of flushing water flowing into the inlet 8a of the drain trap pipe 8.

[0052] As shown in Figure 6A, in a large flush, at time t2, the drain valve 38 is opened and flush water in the water storage tank 4 passes through the jet water conduit 17 and is spouted from the jet water spouting port 14. The instantaneous flow rate of the jet water spouting, shown by the dashed line, increases suddenly immediately after it starts and then remains approximately constant. At time t4, the drain valve 48 is closed, which causes the instantaneous flow rate of the jet water spouting to also decrease.

[0053] The rim water spouting indicated by the dashed dotted line has a constant instantaneous flow rate and is also performed between time t2 and time t4 when jet water spouting is performed. Furthermore, flush water discharged by the rear rim discharge during the previous flush remains in the bowl portion 6 as pooled water. As a result, between time t2 and time t4, the flush water from the rim spout and the accumulated water remaining in the bowl section 6 due to the post-rim spout from the previous flush combine with the flush water from the jet spout, and a large flow rate of flush water flows into the inlet 8a of the drain trap pipe 8, as shown by the solid line.

[0054] As a result, in this embodiment, even if flush water is supplied to the jet water conduit 16 by the head pressure of the flush water in the low-silhouette water storage tank (although siphon action is unlikely to occur with this jet water alone), the flush water from the rim water spout and the pooled water also flow into the inlet 8a of the drain trap pipe 8, so that a strong siphon action can be used to reliably discharge waste.

[0055] After the drain valve 38 closes at time t4, the instantaneous flow rate of the jet water spouting decreases, but the rim water spouting continues at the same instantaneous flow rate. As a result, the instantaneous flow rate of wash water from the jet water spouting and rim water spouting decreases, but this allows the siphon action to continue. In this way, a strong siphoning action can be generated and continued without increasing the amount of water stored in the water storage tank 4, thereby achieving water conservation.

[0056] Next, as shown in Figure 6B, in the small flush, at time t2, the drain valve 38 is opened and flush water in the water storage tank 4 passes through the jet water conduit 17 and is spouted from the jet water spouting port 14. The instantaneous flow rate of the jet water spouting, shown by the dashed line, increases suddenly immediately after it starts and then remains approximately constant. At time t4, the drain valve 48 is closed, which causes the instantaneous flow rate of the jet water spouting to also decrease.

[0057] The rim water spouting indicated by the dashed dotted line has a constant instantaneous flow rate and is also performed between time t2 and time t4 when jet water spouting is performed. Furthermore, flush water discharged by the rear rim discharge during the previous flush remains in the bowl portion 6 as pooled water. For this reason, between time t2 and time t4, flush water from the jet spout and rim spout flows into the inlet 8a of the drain trap pipe 8. However, after time t4, the flush water from the rim spout and the pooled water remaining in the bowl section 6 combine with the flush water from the jet spout, and a large flow rate of flush water flows into the inlet 8a of the drain trap pipe 8, as shown by the solid line.

[0058] As a result, in this embodiment, even in the case of a small flush, even if flush water is supplied to the jet water conduit 16 by the head pressure of the flush water in the low silhouette water storage tank (although siphon action is unlikely to occur with this jet water alone), the flush water from the rim water spout and the pooled water also flow into the inlet 8a of the drain trap pipe 8, so that a strong siphon action can be used to reliably discharge waste.

[0059] Furthermore, after a strong siphoning action occurs, the instantaneous flow rate of flush water from the jet water spout and rim water spout decreases, but this allows the siphoning action to continue. In this way, even in the case of a small flush, a strong siphoning action can be generated without increasing the amount of water stored in the water tank 4, and this siphoning action can be continued, thereby achieving water conservation.

[0060] Next, the effects achieved by the flush toilet according to the embodiment of the present invention described above will be explained. First, in the flush toilet 1 according to this embodiment, flush water is successively discharged from the rim spout 10 in the order of "front rim spouting," "middle rim spouting," and "rear rim spouting," and the sequence is controlled so that "jet spouting" is performed from the jet spout 14 when "middle rim spouting" is being performed, so that the flush water supplied to the bowl section 6 by the front rim spouting and the pooled water remaining in the bowl section 6 by the rear rim spouting during the previous flush combine with the flush water by the jet spouting, causing a large flow rate of flush water to flow into the drain trap pipe 8, and the siphoning action can be continued by the flush water by the subsequent jet spouting and the flush water by the middle rim spouting. As a result, according to this embodiment, even if flush water is supplied to the jet water conduit 16 by the head pressure of the flush water in the water storage tank 4, which has a low silhouette and limited volume, waste can be reliably discharged by the strong siphoning action, and water conservation can also be achieved.

[0061] Secondly, according to the flush toilet 1 of this embodiment, the spouting time of the front rim spout is shorter than the spouting time of the rear rim spout, so the bowl section 6 is flushed with a smaller amount of flush water than the rear rim spout, and furthermore, a siphon effect can be generated by this flush water.

[0062] Thirdly, according to the flush toilet 1 of this embodiment, the total spouting time of the front rim spout and middle rim spout is shorter than the spouting time of the rear rim spout, so that the front rim spout and middle rim spout, which have a smaller amount of flush water than the rear rim spout, can generate a siphoning action together with the jet spout, allowing siphoning to continue.

[0063] Fourthly, with the flush toilet 1 of this embodiment, the stop water level (WL0) of the flush water in the water tank 4 is set higher than the upper surface of the bowl surface 6, allowing for a large head pressure.

[0064] Fifth, with the flush toilet 1 of this embodiment, the flush water stop water level (WL0) in the water tank is set lower than the upper surface of the bowl surface, making it possible to lower the height of the water tank 4 and achieve an even lower silhouette.

[0065] Sixth, with the flush toilet 1 of this embodiment, the controller 29 supplies water to the water tank 4 after rear rim spouting has finished, so rim spouting can continue at a constant flow rate and there is no drop in flow rate. [Explanation of symbols]

[0066] 1 flush toilet 2 Toilet bowl body 4. Water tank 6 Bowl section 8 Drain trap line 8a entrance 8b Ascending Pipe 8c descending pipe 8d top 10 Rim Spout 14 Jet outlet 16 Jet Waterway 18 Waste receiving surface 20 Rim section 24 Water supply equipment 26 Drainage system 28 Float switch 29 Controller 30 Rim side solenoid valve 32 Tank water inlet 34 Tank side solenoid valve 36 Overflow pipe 38 Drain valve 40 Toilet flushing unit W Water sealing surface (water storage surface) WL0 Water stop level DWL dead water level A. Air

Claims

1. A siphon jet type flush toilet, a bowl portion having a waste receiving surface and a rim portion formed along an upper edge of the waste receiving surface; a rim spout formed in the rim portion for spouting flush water into the bowl portion; a drain trap pipe connected below the bowl portion, the drain trap pipe having an ascending pipe extending upward from below the bowl portion, a descending pipe extending downward from the ascending pipe, and a top portion located between the ascending pipe and the descending pipe and defining a seal water level; a jet water outlet disposed below the bowl portion so as to discharge flush water toward an inlet of the drain trap pipe; a water storage tank having a drain valve and configured to store flush water to be supplied to the jet water outlet; a jet water conduit that connects the water storage tank and the jet water outlet and guides flush water from the water storage tank to the jet water outlet through a head of the water storage tank; A control device for controlling the rim water spouting from the rim water spouting port and the jet water spouting from the jet water spouting port, The drain valve includes a valve body, and the valve body is disposed at a position lower than the upper surface of the bowl portion and higher than the seal water level. The control device controls the flush toilet so that flush water is discharged from the rim spout in succession in the order of "front rim spouting," "middle rim spouting," and "rear rim spouting," and also controls so that "jet spouting" is performed from the jet spout when "middle rim spouting" is being performed.

2. 2. The flush toilet according to claim 1, wherein the spouting time of the front rim spouting is shorter than the spouting time of the rear rim spouting.

3. 2. The flush toilet according to claim 1, wherein a total spouting time of the front rim spouting and the middle rim spouting is shorter than a spouting time of the rear rim spouting.

4. 2. The flush toilet according to claim 1, wherein a stop water level of the flush water in the water storage tank is set higher than an upper surface of the bowl surface.

5. 2. The flush toilet according to claim 1, wherein a stop water level of the flush water in the water storage tank is set lower than an upper surface of the bowl surface.

6. 2. The flush toilet according to claim 1, wherein the control device supplies water to the water tank after rear rim spouting has ended.

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