Pilot-operated coolant valve

Abstract

Pilot-operated coolant valve (1) comprising: - a valve housing (6) with a pressure chamber (7), - a closing piston (8) moving in the pressure chamber (7), which divides the pressure chamber (7) into a dynamic pressure chamber (10) and a flow chamber (9), - a coolant inlet (2) and a coolant outlet (4) which open into the flow chamber (9), - a valve seat (16) that limits the opening of the coolant inlet (2), - an electromagnetic actuator (17) with a plunger (19) which, when the actuator (17) is energized, actuates the closing piston (8) in the direction of the valve seat (16), wherein the connection of the coolant inlet (2) with the flow chamber (9) is interrupted when the closing piston (8) is in sealing contact with the valve seat (16), characterized by a 3 / 2-way valve (23) connected to the coolant inlet (2), the back pressure chamber (10) and the flow chamber (9) with a valve piston (22) actuated by the plunger (19), which, when the actuator (17) is not energized, is in its first switching position and thereby blocks the connection to the coolant inlet (2) and connects the back pressure chamber (10) to the flow chamber (9), and which, when the actuator (17) is energized, is in its second switching position and thereby blocks the connection to the flow chamber (9) and connects the coolant inlet (2) to the The stagnation pressure chamber (10) connectswherein the plunger (19) actuates the closing piston (8) by means of the valve piston (22).

Description

[0001] The invention relates to a pilot-operated coolant valve, which in particular controls the coolant flow through the engine block of an internal combustion engine and comprises the following: - a valve body with a pressure chamber, - a closing piston moving within the pressure chamber, which divides the pressure chamber into a dynamic pressure chamber and a flow chamber, - a coolant inlet and a coolant outlet that lead into the flow chamber, - a valve seat that limits the opening of the coolant inlet, - an electromagnetic actuator with a plunger which, when the actuator is energized, actuates the closing piston in the direction of the valve seat, whereby the connection of the coolant inlet to the flow chamber is interrupted when the closing piston is in a sealing position against the valve seat.

[0002] Such a coolant valve is known from the unpublished application DE 10 2019 106 498 A1. The coolant valve operates both as a pilot valve and as a direct valve, in that the plunger actuating the closing piston is simultaneously a pilot control piston.

[0003] Other pilot-operated valves are known from US 2017 / 0 284 277 A1, EP 2 778 364 B1, DE 11 2013 004 902 T5 and DE 10 2004 014 068 A1.

[0004] DE 86 29 171 U1 discloses a pneumatically actuated 2 / 2-way valve with a closing element that can be pneumatically moved into the closed position via a 3 / 2-way solenoid valve.

[0005] The present invention is based on the objective of improving a pilot-operated coolant valve of the type mentioned above with regard to an increased actuating force and sealing effect of the closing piston when the coolant valve is closed.

[0006] The solution for this arises from the features of claim 1. Accordingly, the coolant valve shall comprise a 3 / 2-way valve connected to the coolant inlet, the stagnation chamber and the flow chamber, with a valve piston actuated by the plunger, which, when the actuator is not energized, is in its first switching position and thereby blocks the connection to the coolant inlet and connects the stagnation chamber to the flow chamber, and which, when the actuator is energized, is in its second switching position and thereby blocks the connection to the flow chamber and connects the coolant inlet to the stagnation chamber, wherein the plunger actuates the closing piston by means of the valve piston.

[0007] The design of the coolant valve according to the invention means that the required actuating force of the plunger acting on the closing piston can be comparatively small. Due to the small actuating force, the electromagnet can also be dimensioned accordingly small and thus be designed to be comparatively inexpensive. A further advantageous effect is that the closing piston, which rests against the valve seat, reproducibly leaves the valve seat after the electromagnet is switched off, and consequently the coolant valve reopens under all operating conditions.

[0008] Further features of the invention will become apparent from the following description and from the drawings, in which an embodiment of a coolant valve according to the invention is shown partially schematically. The drawings show: Fig. 1 the coolant valve in longitudinal section; Fig. 2a - 2d the closing and opening process of the coolant valve in different sequences.

[0009] The in Fig. The coolant valve 1 shown in Figure 1 controls the coolant flow through the engine block of an internal combustion engine. The coolant valve 1, which operates both in a pilot and direct-acting manner, has an inlet port 3 forming the coolant inlet 2 and an outlet port 5 forming the coolant outlet 4, both of which are attached to a first housing part 6a of a valve housing 6. Within the first housing part 6a are a pressure chamber 7 and a closing piston 8 moving within it, which divides the pressure chamber 7 into a flow chamber 9 near the inlet and a back pressure chamber 10 further away. The coolant inlet 2 and the coolant outlet 4 open into the flow chamber 9. The division of the pressure chamber 7 is achieved by a hollow cylindrical expansion 11 located at the end of the closing piston 8 furthest from the inlet, the outer surface 12 of which is guided within the inner surface 13 of the pressure chamber 7 to minimize leakage.

[0010] The pressure chamber 7 is axially bounded on the side of the flow chamber 9 by a base 14 of the first housing part 6a and on the side of the dynamic pressure chamber 10 by a base 15 of a second housing part 6b of the valve housing 6 flanged to the first housing part 6a. The base 14 of the first housing part 6a has a valve seat 16 that defines the opening of the coolant inlet 2. When the coolant valve 1 is closed, the inlet-side end of the closing piston 8 seals against this seat, interrupting the connection between the coolant inlet 2 and the flow chamber 9. This condition corresponds to the one described in Fig. 2c shows the stroke position of the closing piston 8.

[0011] The simultaneous pilot control and direct actuation of the closing piston 8 is achieved by means of an electromagnetic actuator 17 with an electrically actuated solenoid 18 and a plunger 19, which moves coaxially to the closing piston 8 in the second housing part 6b and extends when the solenoid 18 is energized, thereby actuating the closing piston 8 in the direction of the valve seat 16. The plunger 19 and the closing piston 8 are each subjected to a force by a plunger spring 20 and a closing piston spring 21, respectively, which act in the opposite direction to the force of the solenoid, i.e., in the opening direction of the coolant valve 1.

[0012] The stroke actuation of the closing piston 8 by the plunger 19 is effected by means of a valve piston 22 of a 3 / 2-way valve 23, whose three ports are the coolant inlet 2, the back pressure chamber 10, and the flow chamber 9. The coolant inlet 2 is connected via a branch extending upstream of the valve seat 16 and in Fig. The bypass 24, shown only schematically, is connected to the 3 / 2-way valve 23. When the actuator 17 is not energized, the valve piston 22 is in its first switching position, in which the stagnation chamber 10 is connected to the flow chamber 9, while the connection to the coolant inlet 2 is closed. When the actuator 17 is energized, the valve piston 22 is in its second switching position, in which the coolant inlet 2 is connected to the stagnation chamber 10, while the connection to the flow chamber 9 is closed.

[0013] The switching positions of the 3 / 2-way valve 23, further design details and the operation of the coolant valve 1 are described below using the following: Fig. Figures 2a-d explain the relevant section for the pilot control of coolant valve 1 in the area of ​​the 3 / 2-way valve 23. Reference numbers not shown there are Fig. 1 can be seen.

[0014] The valve piston 22, actuated by the tappet 19, is joined to the tappet 19 and screwed into its end furthest from the magnet. The tappet 19 passes through a tappet guide bushing 25, which is sealed in the base 15 of the second housing part 6b. In this area, the tappet 19, together with a longitudinally grooved outer surface 26, forms a coolant passage 27 that can be blocked by the valve piston 22. This passage connects the ram air chamber 10 to the coolant inlet 2 via the bypass 24. The coolant passage 27, and thus the connection to the coolant inlet 2, is blocked by the fact that the valve piston 22 is partially shaped as a spherical layer 28, which, in the first switching position of the valve piston 22, seals against the inlet-side end face 29 of the tappet guide bushing 25. The plunger guide bushing 25 can alternatively be omitted, in which case the coolant passage 27 and the end face 29 are formed directly at the bottom 6b.

[0015] The pressure chamber 10 is connected to the flow chamber 9 via a pressure relief channel 30, which can be blocked by the valve piston 22 and runs inside the closing piston 8. The pressure relief channel 30, and thus the connection to the flow chamber 9, is blocked by the fact that the spherical layer 28 of the valve piston 22, in the second switching position of the valve piston 22, abuts the end face 31 of the closing piston 8 furthest from the inlet, forming a seal.

[0016] Regarding the operation of coolant valve 1: Fig. 2a: The coolant valve 1 is fully open for maximum flow between the coolant inlet 2 and the coolant outlet 4. The closing piston 8 is at its maximum distance from the valve seat 16 and, corresponding to the restoring force of the closing piston spring 21, its diameter extension 11 rests against the base 15. The solenoid 18 is not energized, and the plunger 19 is in its retracted position, corresponding to the restoring force of the plunger spring 20. The valve piston 22 is in its first switching position, in which the spherical layer 28 seals against the end face 29 of the plunger guide bushing 25 and blocks the coolant passage 27. In this first switching position, the spherical layer 28 is spaced away from the front face 31 of the closing piston 8, so that the dynamic pressure chamber 10 is connected to the flow chamber 9 via the pressure relief channel 30 and a transverse bore 32 passing through the closing piston 8 and is pressure-balanced. Fig. 2b: The closing process of the coolant valve 1 begins when the solenoid 18 is energized and actuates the plunger 19 – against the restoring force of the plunger spring 20 – in the direction of the closing piston 8. In doing so, the valve piston 22, actuated by the plunger 19, is moved from its first switching position to its second switching position, in which the spherical layer 28 is spaced from the end face 29 of the plunger guide bushing 25 and seals against the end face 31 of the closing piston 8. The coolant inlet 2 is now connected to the stagnation chamber 10 via the bypass 24 and the coolant passage 27, while the connection between the stagnation chamber 10 and the flow chamber 9 is interrupted.The positive coolant pressure difference between the stagnation chamber 10, connected to the coolant inlet 2, and the flow chamber 9 generates a pressure force which, in addition to the electromagnetically generated force of the plunger 19 transmitted via the valve piston 22, acts in the closing direction of the coolant valve 1 and actuates the closing piston 8. Fig. 2c: The stroke actuation of the closing piston 8, generated by both pressure and magnetic force, is complete, and the coolant valve 1 is closed. The closing piston 8 is spaced from the base 15, and its inlet end is in sealing contact with the valve seat 16. The solenoid 18 remains energized, so the valve piston 22 remains in its second switching position. Fig. 2d: The opening process of the coolant valve 1 is initiated by switching off the energization of the solenoid 18. The plunger 19 is actuated in the inward direction by the restoring force of the plunger spring 20 and moves the valve piston 22 from its second switching position back to the first switching position. Due to the pressure equalization that takes place, the closing piston 8 is then only acted upon by the restoring force of the closing piston spring 21 and is returned to the open initial position according to Fig. 2a relocated.

Claims

[1] Pilot-operated coolant valve (1) comprising: - a valve housing (6) with a pressure chamber (7), - a closing piston (8) moving in the pressure chamber (7) which divides the pressure chamber (7) into a dynamic pressure chamber (10) and a flow chamber (9), - a coolant inlet (2) and a coolant outlet (4) which open into the flow chamber (9), - a valve seat (16) which limits the opening of the coolant inlet (2), - an electromagnetic actuator (17) with a plunger (19) which, when the actuator (17) is energised, actuates the closing piston (8) in the direction of the valve seat (16), wherein the connection of the coolant inlet (2) to the flow chamber (9) is interrupted when the closing piston (8) is in sealing contact with the valve seat (16), characterized bya 3 / 2-way valve (23) connected to the coolant inlet (2), the back pressure chamber (10) and the flow chamber (9), with a valve piston (22) actuated by the tappet (19), which is in its first switching position when the actuator (17) is not energized and thereby blocks the connection to the coolant inlet (2) and connects the back pressure chamber (10) to the flow chamber (9), and which is in its second switching position when the actuator (17) is energized and thereby blocks the connection to the flow chamber (9) and connects the coolant inlet (2) to the back pressure chamber (10), wherein the tappet (19) stroke-actuates the closing piston (8) by means of the valve piston (22). [2] Coolant valve (1) according to claim 1, characterized bythat the dynamic pressure chamber (10) is connected to the flow chamber (9) via a pressure relief channel (30) which passes through the end face (31) of the closing piston (8) remote from the inlet and runs in the interior thereof, wherein the valve piston (22) in its second switching position lies sealingly against the end face (31) of the closing piston (8) remote from the inlet and blocks the connection to the flow chamber (9). [3] Coolant valve (1) according to claim 2, characterized by that the valve piston (22) is joined to the tappet (19). [4] Coolant valve (1) according to claim 3, characterized by a tappet guide bushing (25) inserted in the valve housing (6) with a coolant passage (27) via which the dynamic pressure chamber (10) is connected to the coolant inlet (2), wherein the valve piston (22) in its first switching position lies sealingly against the end face (29) of the tappet guide bushing (25) near the inlet and blocks the connection to the coolant inlet (2). [5] Coolant valve (1) according to claim 4, characterized by that the closing piston (8) is shaped in sections as a spherical layer (28) which lies sealingly against the end faces (29, 31) of the tappet guide bush (25) and the closing piston (8). [6] Coolant valve (1) according to one of the preceding claims, characterized by that the tappet (19) is subjected to force by a tappet spring (20) in the opening direction of the coolant valve (1). [7] Coolant valve (1) according to one of the preceding claims, characterized by that the closing piston (8) is subjected to force by a closing piston spring (21) in the opening direction of the coolant valve (1).

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